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	England and Wales High Court (Queen's Bench Division) Decisions
You are here: BAILII >> Databases >> England and Wales High Court (Queen's Bench Division) Decisions >> McGuinn v Lewisham And Greenwich NHS Trust [2017] EWHC 88 (QB) (26 January 2017) URL: http://www.bailii.org/ew/cases/EWHC/QB/2017/88.html Cite as: [2017] EWHC 88 (QB)

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IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION

		Royal Courts of Justice Strand, London, WC2A 2LL
		26 January 2017

Annexed to this judgment is a list of medical acronyms.

Mr Justice Jeremy Baker:

1. Amanda McGuinn ("the claimant") is 38 years of age, (dob 14^th August 1978), and has two children, namely Cillian and Matilda.
2. The claimant's first pregnancy was largely uneventful; albeit, during the 3^rd trimester, she suffered from pregnancy induced hypertension. However, at 39 weeks, the claimant gave birth to a healthy son, Cillian, on 20^th February 2007.
3. Later that year the claimant again became pregnant, and, during the course of 2008, underwent a series of ultrasound scans at Lewisham Hospital, where she was under the care of medical staff for whom the Lewisham & Greenwich NHS Trust ("the defendant") is responsible.
4. Unfortunately, after Matilda was born, on 16^th August 2008, she was found to suffer from severe neurodevelopmental impairment, and is profoundly physically and cognitively disabled. Although the precise cause of these disabilities is unclear, at birth Matilda's head circumference was found to be well below the 0.4^th centile, and, subsequently, her head was diagnosed to be microcephalic; a condition which is known to give rise to a substantial risk of physical and mental abnormalities.
5. It is the claimant's case that, bearing in mind the features revealed on the scans, including, the small fetal head circumference, the decrease in growth rate, the slightly enlarged cerebral ventricles, and the presence of a single umbilical artery, those responsible for her medical care during the course of her second pregnancy should have been aware that the fetus was at risk of suffering from microcephaly. In which case she should have been referred for further investigations and assessment at tertiary level care, and thereafter been informed of the substantial risk of physical and mental abnormalities associated with this condition. It is the claimant's case that if she had been aware of this risk, then she would have elected to terminate her pregnancy.
6. The claimant alleges that the failure, on the part of those responsible for her medical care, to appreciate that the fetus was at risk suffering from microcephaly and refer the claimant for tertiary level investigation and assessment, amounts to clinical negligence, and she seeks damages for the wrongful birth of her child. The defendant denies negligence, asserting that, antenatally, there was no or insufficient evidence that the fetus was at risk of suffering from microcephaly.
7. Although various issues including causation are in dispute between the parties, at this stage the only determination which is required, is whether the claimant is able to establish, on the balance of probabilities, that those responsible for her medical care were in breach of their duty of care in failing to appreciate that the fetus was at risk of suffering from microcephaly, and refer the claimant for tertiary level investigation and assessment.

Legal principles

8. This being a case in which clinical negligence is alleged, the starting point for the correct approach to the assessment of liability, is the case of Bolam v Friern Hospital Management Committee [1957] 1WLR 583, in which McNair J. stated that,

"I would myself prefer to put it this way, he is not guilty of negligence if he has acted in accordance with a practice accepted as proper by a responsible body of medical men skilled in this particular art……Putting it the other way around, a man is not negligent, if he is acting in accordance with such a practice, merely because there is a body of opinion that would take a contrary view."

9. As Lord Scarman in Maynard v West Midlands RHA [1984] 1WLR 634 expressed it,

"Differences of opinion and practice exist and will always exist in the medical and other professions. There is seldom only one answer exclusive of all others to problems of professional judgment. A Court may prefer one body of opinion to the other, but that is no basis for a conclusion of negligence."

10. However, as was made clear by the House of Lords in Bolitho v City and Hackney Health Authority [1998] AC 232, as it is ultimately the court which has to determine the issue of negligence, it is necessary for the court to be satisfied that the responsible body of medical opinion relied upon by a clinician, has a sufficiently logical basis. As Lord Browne-Wilkinson stated,

"……..the Court has to be satisfied that the exponents of the body of opinion relied upon can demonstrate that such opinion has a logical basis. In particular, in cases involving, as they so often do, the weighing of risks against benefits, the judge before accepting a body of opinion as being responsible, reasonable or respectable, will need to be satisfied that, in forming their views, the experts directed their minds to the question of comparative risks and benefit and have reached a defensible conclusion on the matter……

In the vast majority of cases the fact that distinguished experts in the field are of a particular opinion will demonstrate the reasonableness of that opinion. In particular, where there are questions of assessment of the relative risks and benefits of adopting a particular medical practice, a reasonable view necessarily pre-supposes that the relative risks and benefits have been weighed by the experts in forming their opinions. But if, in a rare case, it can be demonstrated that the professional opinion is not capable of withstanding logical analysis, the judge is entitled to hold that the body of opinion is not reasonable or responsible."

11. In this context, a recent and helpful analysis of the matters which are likely to be relevant to the Court's consideration of medical evidence has been provided by Green J. in the case of C v North Cumbria University Hospitals NHS Trust [2014] EWHC 61, in which he stated that,

"25. In the present case I have received evidence from 4 experts, 2 on each side. It seems to me that in the light of the case law the following principles and considerations apply to the assessment of such expert evidence in a case such as the present:

i) Where a body of appropriate expert opinion considers that an act or omission alleged to be negligent is reasonable a Court will attach substantial weight to that opinion.

ii) This is so even if there is another body of appropriate opinion which condemns the same act or omission as negligent.

iii) The Court in making this assessment must not however delegate the task of deciding the issue to the expert. It is ultimately an issue that the Court, taking account of that expert evidence, must decide for itself.

iv) In making an assessment of whether to accept an expert's opinion the Court should take account of a variety of factors including (but not limited to): whether the evidence is tendered in good faith; whether the expert is "responsible", "competent" and/or "respectable"; and whether the opinion is reasonable and logical.

v) Good faith: A sine qua non for treating an expert's opinion as valid and relevant is that it is tendered in good faith. However, the mere fact that one or more expert opinions are tendered in good faith is not per se sufficient for a conclusion that a defendant's conduct, endorsed by expert opinion tendered in good faith, necessarily accords with sound medical practice.

vi) Responsible/competent/respectable: In Bolitho Lord Brown Wilkinson cited each of these three adjectives as relevant to the exercise of assessment of an expert opinion. The judge appeared to treat these as relevant to whether the opinion was "logical". It seems to me that whilst they may be relevant to whether an opinion is "logical" they may not be determinative of that issue. A highly responsible and competent expert of the highest degree of respectability may, nonetheless, proffer a conclusion that a Court does not accept, ultimately, as "logical". Nonetheless these are material considerations. In the course of my discussions with Counsel, both of whom are hugely experienced in matters of clinical negligence, I queried the sorts of matters that might fall within these headings. The following are illustrations which arose from that discussion. "Competence" is a matter which flows from qualifications and experience. In the context of allegations of clinical negligence in an NHS setting particular weight may be accorded to an expert with a lengthy experience in the NHS. Such a person expressing an opinion about normal clinical conditions will be doing so with first hand knowledge of the environment that medical professionals work under within the NHS and with a broad range of experience of the issue in dispute. This does not mean to say that an expert with a lesser level of NHS experience necessarily lacks the same degree of competence; but I do accept that lengthy experience within the NHS is a matter of significance. By the same token an expert who retired 10 years ago and whose retirement is spent expressing expert opinions may turn out to be far removed from the fray and much more likely to form an opinion divorced from current practical reality. "Respectability" is also a matter to be taken into account. Its absence might be a rare occurrence, but many judges and litigators have come across so called experts who can "talk the talk" but who veer towards the eccentric or unacceptable end of the spectrum. Regrettably there are, in many fields of law, individuals who profess expertise but who, on true analysis, must be categorised as "fringe". A "responsible" expert is one who does not adapt an extreme position, who will make the necessary concessions and who adheres to the spirit as well as the words of his professional declaration (see CPR35 and the PD and Protocol).

vii) Logic/reasonableness: By far and away the most important consideration is the logic of the expert opinion tendered. A Judge should not simply accept an expert opinion; it should be tested both against the other evidence tendered during the course of a trial, and, against its internal consistency. For example, a judge will consider whether the expert opinion accords with the inferences properly to be drawn from the Clinical Notes or the CTG. A judge will ask whether the expert has addressed all the relevant considerations which applied at the time of the alleged negligent act or omission. If there are manufacturer's or clinical guidelines, a Court will consider whether the expert has addressed these and placed the defendant's conduct in their context. There are 2 other points which arise in this case which I would mention. First, a matter of some importance is whether the expert opinion reflects the evidence that has emerged in the course of the trial. Far too often in cases of all sorts experts prepare their evidence in advance of trial making a variety of evidential assumptions and then fail or omit to address themselves to the question of whether these assumptions, and the inferences and opinions drawn therefrom, remain current at the time they come to tender their evidence in the trial. An expert's report will lack logic if, at the point in which it is tendered, it is out of date and not reflective of the evidence in the case as it has unfolded. Secondly, a further issue arising in the present case emerges from the trenchant criticisms that Mr Spencer QC, for the Claimant, made of the Defendant's two experts due to the incomplete and sometimes inaccurate nature of the summaries of the relevant facts (and in particular the Clinical Notes) that were contained within their reports. It seems to me that it is good practice for experts to ensure that when they are reciting critical matters, such as Clinical Notes, they do so with precision. These notes represent short documents (in the present case two sides only) but form the basis for an important part of the analytical task of the Court. If an expert is giving a précis then that should be expressly stated in the body of the opinion and, ideally, the Notes should be annexed and accurately cross-referred to by the expert. If, however, the account from within the body of the expert opinion is intended to constitute the bedrock for the subsequent opinion then accuracy is a virtue. Having said this, the task of the Court is to see beyond stylistic blemishes and to concentrate upon the pith and substance of the expert opinion and to then evaluate its content against the evidence as a whole and thereby to assess its logic. If on analysis of the report as a whole the opinion conveyed is from a person of real experience, exhibiting competence and respectability, and it is consistent with the surrounding evidence, and of course internally logical, this is an opinion which a judge should attach considerable weight to.

Evidence

Ultrasound scans

12. Whilst Mrs McGuinn was under the care of medical staff at Lewisham Hospital she underwent a series of 10 ultrasound scans between 28^th January and 15^th August 2008. A review of the printed scan results reveals the following:

i. The 1^st scan was undertaken on 28^th January 2008 at 10 + 6 weeks' (i.e. 10 weeks and 6 days) gestation, and was for the purpose of dating the fetus, as a result of which a delivery date of 19^th August 2008 was ascertained.

ii. The 2^nd scan was undertaken on 7^th February 2008 at 12+2 weeks' gestation. Nuchal translucency was found to be 1.8, and the report noted that,

"The nuchal scan has decreased the risk of Down's syndrome and this is a low risk result. The mother is aware that a low risk result does not exclude the possibility of Down's syndrome because screening does not detect all affected pregnancies. Written information provided on screening for preterm delivery by ultrasound. The next scan is at 21 weeks approximately."

iii. The 3^rd scan was undertaken on 9^th April 2008 at 21+1 weeks' gestation, by the ultrasonographer Andrew Zavos. This was a routine anomaly scan, and the resulting body measurements were recorded on the Astraia database as showing a head circumference of 177.5mm, a femur length of 33.2mm, and an abdominal circumference of 160.4mm. The HC/AC ratio was 1.11, and the estimated fetal weight was 376g. The Va left was 5.2mm, and the Vp left was 6.8mm, whilst the Va/H was 0.25 and the Vp/H was 0.32. Amniotic fluid was normal. Mr Zavos reported that there was,

"Normal fetal growth and liquor volume. Single umbilical artery, bilaterally dilated anterior horns. The mother is aware that not all fetal abnormalities can be identified by ultrasound…..."

It would appear that as a result of the reported presence of a single umbilical artery, a referral was made to the specialist fetal medicine midwife, Sue Percival, who in turn arranged for the next scan to be undertaken by Mr Sau, the fetal medicine consultant.

iv. The 4^th scan was undertaken on 23^rd April 2008 at 23+1 weeks' gestation, by Mr Sau. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 197mm, a femur length of 39mm, and an abdominal circumference of 174mm. The HC/AC ratio was 1.13, and the estimated fetal weight was 497g. The Va left was 8.0mm, and the Vp left was 8.0mm, whilst the Va/H was 0.31 and the Vp/H was 0.31. Amniotic fluid was normal. Mr Sau reported that,

"Amanda attended today in view of detection of single umbilical artery. I agree with finding and the left umbilical artery is absent. No other structural abnormality was seen particularly the brain, kidneys and heart looked normal. I note a low risk NT result. I have explained the significance of this finding and rescan her at 30 weeks……."

v. The 5^th scan was undertaken on 11^th June 2008 at 30+1 weeks' gestation, again by Mr Sau. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 258mm, a femur length of 56mm, and an abdominal circumference of 239mm. The HC/AC ratio was 1.08, and the estimated fetal weight was 1257g. Amniotic fluid was normal. Mr Sau reported that,

"Amanda attended today for a growth scan in view of detection of single umbilical artery. There was normal growth, liquor and UA Doppler. The HC remain at the 3rd centile with normal interval growth. I will arrange another scan at 34 weeks in the main scan dept."

vi. The 6^th scan was undertaken on 15^th July 2008 at 35+0 weeks' gestation, by the ultrasonographer Dorothy Speddings. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 281mm, a femur length of 60.3mm, and an abdominal circumference of 270.8mm. The HC/AC ratio was 1.04, and the estimated fetal weight was 1713g. The ventricular atrium was 10.3mm, and the amniotic fluid was normal. Ms Speddings reported that,

"The growth rate of all the growth parameters has slowed down. BPD and HC are now below the 5th centile and FL & AC just above 5th centile. The ventricles appear mildly dilated. Posterior horns measure 10.2mm. Third ventricle slightly visible. ?slightly prominent sulcii in temporal lobes ?? mild atrophic changes. In addition to growth reduction and cranial appearances the 2 vessel cord appears to be inserted marginally at the fundal margin of the anterior placenta. Doppler examination of the umbilical artery demonstrated adequate EDF but the PI was raised and close to 95th centile. I have referred Amanda to King's for further assessment as Mr Sau is not available for 3 weeks."

vii. The 7^th scan was undertaken on the following day, 16^th July 2008, at 35+1 weeks' gestation, by Miss Abdo-Nassri, a specialist in fetal medicine, based at King's College Hospital, but running an outreach clinic at Lewisham Hospital, where the scan took place. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 287mm, a femur length of 68mm, and an abdominal circumference of 259mm. The HC/AC ratio was 1.11, and the estimated fetal weight was 1888g. The amniotic fluid was normal. Miss Abdo-Nassri reported that,

"Mrs Mc Guinn has been referred to FMU in view of single umbilical artery, HC below the 3rd centile, velamentous cord insertion and enlarged posterior horn of the lateral ventricle (10.2mm). On today's scan I agree with small HC and velamentous cord insertion. However the VP measured 9.5mm. Otherwise there is satisfactory growth velocity, liquor volume and umbilical artery doppler. She has good fetal movements. We will rescan in 2 weeks time. We may consider Brain MRI post delivery."

viii. The 8^th scan was undertaken on 31^st July 2008 at 37+2 weeks' gestation, by Mr Sau. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 299mm, a femur length of 63mm, and an abdominal circumference of 280mm. Mr Sau reported that,

"Amanda returned today for rescan in view of small HC on previous scan. The HC remain below 3rd centile with normal interval growth. The posterior horn measured 9mm with normal VpH ratio. The liquor and UA Doppler were normal. I have not made further FU appointment."

ix. The 9^th scan was undertaken on 7^th August 2008 at 38+2 weeks' gestation, by Diana Avis superintendent sonographer. She noted that,

"NB growth scan 31/10/08. Two vessel cord noted. Doppler examination of the umbilical artery demonstrated adequate EDF and the PI was normal. Fetal head posterior horn 9mm. Referred back to DAU for review."

x. The 10^th scan was undertaken on 15^th August 2008 at 39+3 weeks' gestation, by the ultrasonographer Richard Wilsey, and Nihal Emmanuel. The resulting body measurements were recorded on the Astraia database as showing a head circumference of 296mm, a femur length of 65mm, and an abdominal circumference of 273mm. The HC/AC ratio was 1.08 and the estimated fetal weight was 1954g. Richard Wilsey and Nihal Emmanuel reported that,

"The scan today demonstrates reduced growth velocity and liquor volume. Compared to the previous scan there has been no growth (checked by a second sonographer) PI is high (above 97th centile). Referred to the Day Assessment Unit for review for medical review."

13. As a result of a medical review which was carried out on 15^th August 2008, labour was induced, and the subsequent birth of Matilda took place on the following day, 16^th August 2008. Matilda was transferred to the specialist baby unit where a number of features were identified, including growth restriction, the head circumference was measured at 29.5cm and dysmorphic features, including overlapping digits and rocker bottom feet.

Mr Ashis Sau

14. Mr Ashis Sau is a Consultant Obstetrician and Gynaecologist, with a sub-specialism in Maternal and Fetal Medicine. He commenced work at Lewisham Hospital in 2004, and was the consultant in charge of the claimant's care during her pregnancy in 2008.
15. In his witness statement, dated 24^th September 2015, he stated that his initial contact with the claimant was following the 3^rd scan carried out by the ultrasonographer Andrew Zavos, on 9^th April 2008, who had reported that not only was there a single umbilical artery, but that there were bilateral dilated anterior horns. As a result of these findings, the fetal medicine midwife, Sue Percival, had referred the matter to Mr Sau, who reviewed the scan and considered that the ventricular measurements were within the normal range, being Va left 5.2 and Vp left 6.8.
16. However, due to the reported presence of the single umbilical artery, Mr Sau carried out the 4^th scan himself on 23^rd April 2008. He was able to confirm the presence of the single umbilical artery, and measured the ventricles at Va left 8.0 and Vp left at 8.0, both of which were within the normal range. He stated that there was no other structural anomaly, in particular the brain, heart and kidneys looked normal. He measured the head circumference at 197mm. As this was just above the 3^rd centile, which was normal, and as the graph showed a similar centile reading for the previous scan, he considered that the fetus, whilst small, was growing appropriately, and was not a growth restricted baby due to any placental insufficiency.
17. Mr Sau also undertook the 5^th scan on 11^th June 2008. He measured the head circumference at 258mm, which was just below the 3^rd centile. He said that this indicated adequate interval growth, and, that as a head circumference on the 3^rd centile is equivalent to 2 standard deviations below the mean, he didn't suspect the presence of microcephaly, as this is diagnosed when the head circumference is 3 standard deviations below the mean. He said that at no point during the claimant's pregnancy was the fetus' head circumference found to be 3 standard deviations below the mean. He said that, using the "red dot chart", the head circumference/abdominal circumference ratio of 1.08 was on the 50^th centile, which was normal. He said that in a fetus with microcephaly, he would expect to see the HC/AC to be abnormally low. He said that the liquor and umbilical artery Doppler measurements were normal, and his conclusion was that, whilst the fetus was small, it was not a growth restricted baby due to placental insufficiency or any other abnormality.
18. He said that he arranged for the next scan to take place at 34 weeks' gestation, albeit its timing was a guide rather than a requirement, and it took place at 35 weeks' gestation. He said that because of the sonographer's concerns arising from certain of the fetal measurements which were obtained at the 6^th scan, it was necessary, in line with departmental policy, for the claimant to be re-scanned by a Fetal Medicine Consultant, prior to referring a patient to a tertiary centre. Therefore, in his absence, this was carried out by Miss Abdo-Nassri.
19. The 7^th scan revealed a measurement of the posterior horn of the lateral ventricle of 9.5mm which was within the normal range; 10mm being considered to be normal. Moreover, the HC/AC ratio was 1.11 which was normal, according to the red dot chart. He said that the expected mean ratio at that stage was 1.02, such that the recorded ratio was at the 95^th centile.
20. Mr Sau said that he carried out the 8^th scan, and that the head circumference remained below the 3^rd centile, which is 2 standard deviations below the mean, and indicated normal interval growth. Moreover, the lateral ventricle measurement was 9mm, and the hemisphere ventricle ratio was normal, as were the liquor and umbilical artery doppler measurements. He said that the HC/AC ratio was 1.07 which is higher than the expected mean of 0.98, and would not indicate microcephaly to him, rather it might indicate a growth restriction of the abdomen, the most likely cause of which would be a placental insufficiency. He considered that the fetus was simply small, and therefore there was no need to see the claimant on a further occasion.
21. In examination in chief, Mr Sau said that by the time he was carrying out the scans on the claimant, he had about 4 years' experience as a consultant. He said that whilst he sees growth restricted fetus about 2 -3 times a week, he sees a microcephalic fetus less than once a year.
22. In relation to the 4^th scan, he said that because of the presence of a single umbilical artery, which can be associated with restrictive fetal growth, he had checked the fetus' growth measurements. He said that at this stage of gestation, the head circumference should be greater than the abdominal circumference. Therefore, when he saw that the HC/AC ratio was 1.13 he considered this to be satisfactory. He checked to see whether there were any structural abnormalities and found none. He said that after inputting the fetal measurements into the Astraia system, he pressed F7, which caused the growth charts to be visible, from which he could see that the fetus' head was growing about the 3^rd centile, as it had been on the previous scan.
23. In relation to the 5^th scan, he said he input the fetal measurements into the Astraia system, and again pressed F7, looked at the growth charts and saw that the head circumference was just below the 3^rd centile. However, he also noted from the bar charts that the HC/AC was on the 50^th centile, and concluded that whilst there was some slowing of growth, there had still been significant growth from the previous scan, which is why he had reported that there had been, "normal interval growth." He said that he didn't suspect the presence of microcephaly because the head circumference was always above that of the abdomen, and a head circumference just below the 3^rd centile would not be considered to be microcephalic.
24. In the early stages of cross-examination, Mr Sau appeared to express some confusion between the appropriate criteria for microcephaly, namely whether it was that a fetus' head circumference was below the 3^rd centile, or whether it was that the head circumference was more than 3 standard deviations below the mean. However, when he appreciated his confusion, he confirmed that it was the latter criterion. On this basis, Mr Sau agreed that at birth, Matilda, despite being symmetrically small, was microcephalic, in that she had a head circumference which was more than 3 standard deviations below the mean.
25. However, he said that in clinical practice, when considering the potential significance of the scan results, he does not calculate the standard deviation which the fetal measurement represents, rather he looks to see whether the head circumference is below the 3^rd centile, and then assesses this within the context of the HC/AC ratio, in order to see whether the latter is within the normal range. He said that if the head circumference is well below the 3^rd centile, then this may indicate the presence of microcephaly, albeit he would also consider the issue of interval growth from the previous scans. Initially he said that if the head circumference is on the 3^rd centile then he would consider the head circumference to be normal. However, he subsequently agreed that a head circumference on or below the 3^rd centile raises possible concerns about the presence of microcephaly, and that if there has been a significant reduction in interval growth from the previous scans, then he would consider whether microcephaly was present. In this regard, whilst he would not consider a reduction in interval growth from the 5^th to the 3^rd centile to be significant, he would consider a reduction from the 50^th to the 3^rd centile to be significant.
26. Mr Sau said that when he carried out the 4^th scan, he had available to him the previous scan results, and his assessment of the head circumference measurement obtained in the 3^rd scan was that it was just above the 3^rd centile. However, when he was referred to the bar chart from the 3^rd scan, he agreed that this appeared to show that the head circumference was between the 30^th – 40^th centile. He said that in practice, although the bar charts are the first page of results which appear on the Astraia system, he doesn't look at these, and instead immediately presses F7, causing the growth charts to appear on the screen, and it is these which he uses to assess the significance of the fetal measurements, as they show the growth trends. He said that once having done this, he wouldn't refer back to the bar charts, as he wouldn't attach any significance to them, because what he is really interested in is the growth pattern, rather than the precise centile measurement. However, he accepted that not only did the bar charts from the instant scan remain accessible on the Astraia system, but so too did the charts from the previous scans. He said that looking at the bar chart from the 4^th scan, he considered that this showed that the head circumference measurement was between the 20^th – 25^th centile.
27. Mr Sau agreed that, in relation to the 4^th scan, there appeared to be a 5mm discrepancy between the head circumference measurement which he had entered onto the ultrasound scan, being 192mm, and the head circumference measurement which he had then entered onto the Astraia system, namely 197mm. He said that although he has no recollection about this, he believes that what may have occurred is that after he had measured the head circumference on the scan and entered the figure of 192mm, it triggered a thought that he may not have carried out the measurement properly. So that he would then have re-measured the head circumference, and obtained the figure of 197mm, and whilst he input this figure into the Astraia system, he omitted to input it into the scanner.
28. He said that the purpose of carrying out the 4^th scan had been to check for fetal anomalies, in view of the previous finding of a single umbilical artery, and dilated ventricles. He said that despite the fact that the template which he had used for the 4^th scan was for a growth scan, as opposed to an anomaly scan, he had made all of the necessary checks for abnormalities and found none, save for the confirmation of the single umbilical artery. He said that the conclusion which he reached by the end of the 4^th scan, was that the fetus was just a constitutionally small baby, and there were no other concerns.
29. In relation to the 5^th scan Mr Sau agreed that if one looked at the previous bar charts, there had been a dramatic fall in the head circumference centiles from around the 40^th centile at the 3^rd scan, to around the 25^th centile at the 4^th scan, to just above the 3^rd centile at the 5^th scan; albeit on the instant growth chart, his reading of it was that the head circumference measurement was just below the 3^rd centile. He accepted that this fall in the head circumference was not a matter which he would have appreciated at the time, because he only looked at the growth charts, rather than looking back at the bar charts.
30. Mr Sau provided differing accounts of the significance of such a fall in head measurement centiles. Initially he said that, unlike a fall from the 50^th to the 3^rd centile, he did not consider a fall from around the 40^th to the 3^rd centile to be clinically significant. He then conceded that such a fall would have triggered referral to tertiary care, before drawing back from this apparent concession, and said that a fall from around the 40^th to the 3^rd centile would have meant that he would have looked at the fetus with more care and kept the claimant under closer observation, due to the fact that he would have considered that the fetus was possibly growth restricted. However, he said that, apart from carrying out an MRI, all of this could have been achieved by him at Lewisham Hospital.
31. He was referred to his witness statement, and in particular the references to standard deviations below the mean in order to diagnose microcephaly. He agreed that in his evidence at court he had stated that, in clinical practice, he didn't use fetal measurements to calculate standard deviations below the mean. However, he said that he was aware of the use of standard deviations below the mean in order to diagnose microcephaly, and that his understanding was that a variation of at least 3 standard deviations below the mean was required for such a diagnosis. He said that prior to reading Mr Howe's report, he hadn't been aware that the head circumference measurements recorded at the 6^th scan were considered to be more than 3 standard deviations below the mean.
32. Mr Sau said that part of his reasoning for reporting that there was normal growth at the 5^th scan was because the HC/AC was within the normal range; albeit he agreed that the presence of a normal HC/AC ratio doesn't preclude the presence of microcephaly. He agreed that if one looked at the bar charts, there appeared to be a more significant fall in the head circumference, compared to the abdominal circumference and femur length. However, he said that he only looked at the growth charts, rather than the bar charts, and this feature was unclear from the growth charts.
33. He was again referred to his witness statement, and in particular the reference in paragraph 31 to the figure of 1.02 as being the expected mean HC/AC ratio at 35 weeks' gestation. Initially he said that this figure came from the scan records, and then he said that he had obtained it from the Snijders et al study. When it was pointed out that neither the scan records, nor Snijders et al study shows this figure, he denied that he had obtained the figure from any previous report provided by Mr Howe. In re-examination, after having been referred to Table I of the study by Campbell et al, "Ultrasound Measurement of the Fetal Head to Abdomen Circumference Ratio in the Assessment of Growth Retardation" in the British Journal of Obstetrics and Gynaecology, 1977, he suggested that this may have been the source of the figure. He denied that his views about the significance of HC/AC ratios had been influenced by having read Mr Howe's report. He agreed that he hadn't commented upon the significance of the HC/AC ratios in any of his scan reports, but said that if the ratio is shown to be within the normal range, he wouldn't include this within his report. He said that he believed that the reference to the HC/AC ratio being at the 95^th centile came from the bar chart.
34. He accepted that his own measurement of the fetus' head circumference at the 8^th scan, 299mm, appeared to be larger than that obtained by the sonographers at the 10^th scan, 296mm, and the measurement at birth which was recorded as being 29.5cm. He also agreed that whilst Fetal Medicine Consultants may obtain fetal measurements about 3 or 4 times a week, sonographers carry out this type of measurement about 16 or 17 times a week. However, he said that he believed that his own measurement was more likely to be accurate.
35. In re-examination Mr Sau reiterated that when assessing the significance of the scanned measurements of the fetus' head circumference, he referred to the growth charts, rather than the bar charts, and that he had never considered that they showed that Matilda's head was more than 3 standard deviations from the mean. In these circumstances, and bearing in mind that the HC/AC was never abnormally low, he didn't consider that there was a risk that Matilda may be microcephalic.

Miss Abdo-Nassri

36. I understand that, sadly, since these events took place, Miss Abdo-Nassri has died and, save for the report which she compiled at the 7^th scan, there is no other evidence available from her.

Expert Reports

Mr Myles Taylor

37. Mr Taylor is a Consultant Gynaecologist and Obstetrician based at the Royal Devon & Exeter Hospital NHS Trust. Following his consideration of the claimant's obstetric records, he provided an initial report dated November 2015, and thereafter contributed to joint reports with Mr Howe, dated 14^th August 2016 and 4^th October 2016.
38. In his review of the ultrasound scan records, Mr Taylor noted that the 1.8mm nuchal translucency, recorded in the 2^nd scan, meant that there was only a low risk of Down's syndrome.
39. He stated that the 3^rd scan was a routine anomaly scan, and that the fetal biometry was found to be normal, with the head circumference being plotted on the bar chart at around the 30 – 40^th centile. He was unclear why the sonographer had reported that there were bilaterally dilated anterior horns, as the recorded measurements were within the normal range, and when he reviewed the ultrasound pictures, he was of the opinion that the brain anatomy appeared to be normal. However, the finding of a single umbilical artery was a matter of concern, as it is associated with a risk of growth restriction. Therefore, it was appropriate for the matter to be discussed with the claimant, which it was, and for a further anomaly scan to take place.
40. Mr Taylor stated that the fetal anatomy remained normal at the 4^th scan, with the head circumference being plotted on the bar chart at around the 30^th centile. He stated that although Mr Sau confirmed the existence of the single umbilical artery, he found no other structural abnormality. Mr Taylor confirmed that when he reviewed the ultrasound pictures, he too was of the opinion that the brain anatomy appeared to be normal. However, he noted that although the estimated fetal weight had not been plotted on the growth charts, it had reduced from about the 24^th centile on the previous scan, to the 13^th centile on the present one. Mr Taylor stated that despite this evidence of diminished fetal growth, Mr Sau arranged for the next scan to take place 7 weeks later at 30 weeks' gestation.
41. Mr Taylor said that the measurement of the head circumference at the 5^th scan had been plotted on both the growth chart and the bar chart on or below the 3^rd centile. He said that despite this measurement, Mr Sau had considered that there was normal growth, and arranged for the next scan to take place 4 weeks later at 34 weeks' gestation.
42. Mr Taylor noted that the 6^th scan did not in fact take place until 35+0 weeks' gestation. He noted that although the head circumference at this scan was reported to be below the 5^th centile, it had in fact been plotted on both the growth chart and the bar chart, at a position "very much" below the 3^rd centile. Moreover, Mr Taylor was of the opinion that the ventricular atrium measurement of 10.3mm, which he confirmed on review of the ultrasound pictures, but reported as "Posterior horns measure 10.2mm" by Dorothy Speddings, indicated that there was borderline ventriculomegaly.
43. Mr Taylor noted that although Dorothy Speddings had, in the absence of Mr Sau, referred the claimant to King's College Hospital for further assessment, the 7^th scan which took place on the following day at 35+1 weeks' gestation, was carried out by Miss Vian Abdo-Nassri, a specialist in fetal medicine at King's who ran an outreach clinic at Lewisham Hospital. Miss Abdo-Nassri measured the head circumference as being slightly larger, at 287mm, but the posterior atrial width as being slightly smaller at 9.5mm. Mr Taylor was of the opinion that because the previous measurement of the ventricle width had been carried more in accordance with the recommended method of being within the inner edge of the ventricle and perpendicular to its long axis, the previous measurement of 10.3mm, was likely to be the more accurate measurement than the latter one of 9.5mm. Mr Taylor noted that although Miss Abdo-Nassri agreed in her report that the head circumference was small, she considered that otherwise there was satisfactory growth velocity, and arranged for the next scan to take place 2 weeks later, at 37 weeks' gestation. However, he also noted that Miss Abdo-Nassri had stated in her report that, "We may consider Brain MRI post delivery."
44. Mr Taylor noted that the 8^th scan was again carried out by Mr Sau, who had reported that the head circumference remained below the 3^rd centile, and that the left posterior ventricle measured 9mm with normal VpH ratio.
45. Mr Taylor noted that it was the results of the 10^th scan which prompted the sonographers to refer the claimant for medical assessment, which in turn prompted induction of labour on the same day. The head circumference had remained below the 3^rd centile, and the sonographers reported that there was reduced growth velocity and liquor volume.
46. Following Matilda's birth, it was noted that she had growth restriction and oxygen dependency, with dysmorphic features, including overlapping digits, and rocker bottom feet. Moreover, her head circumference was measured at 29.5cm, which Mr Taylor considered to be much lower than the 0.4^th centile, and over 4 standard deviations below the mean. However, karyotyping was normal, and on 30^th April 2009 the Locum Consultant in Clinical Genetics, Dr Lema Roberts, wrote to the claimant stating that there was no explanation for Matilda's developmental problems, and other features. It was not until 1^st July 2009 that Matilda's microcephaly was mentioned, which was apparently confirmed by an MRI in September 2010.
47. Mr Taylor stated that the clinical importance of microcephaly is that it is associated with developmental delay, as the majority of microcephalic children have such delays. The condition is difficult to diagnose antenatally, and, that in this context, serial ultrasound examinations are important, as it may not manifest until the 3^rd trimester. He stated that microcephaly is part of many different syndromes, and that it is therefore important to search for associated anomalies, including ventriculomegaly. He stated that the microcephaly has been classified as a head circumference smaller than either 2 or 3 standard deviations below the mean, and that the latter may correlate better with developmental delay. However, in clinical practice, as standard deviations from the mean are cumbersome to calculate, ultrasonographers usually plot the fetal head measurement onto a bar chart or graph, and it is from these readings that the presence of microcephaly can be detected, as a progressively small head in centile terms over the 2^nd and 3^rd trimester is likely to meet the standard deviation below the mean diagnostic criteria for the condition. This is because unlike standard deviations from the mean, normal head growth should continue along the same centile throughout gestation.
48. Mr Taylor acknowledged that a small head circumference measurement may occur as part of overall growth restriction affecting other parts of the fetus. Indeed, this is the more common presentation. In contrast, microcephaly involves an underlying condition affecting the development of the brain. Therefore, ultrasound reports often include head circumference/abdominal circumference ("HC/AC") ratios, to assist in distinguishing between an overall growth restriction, which maybe indicated by a normal HC/AC ratio, and microcephaly which maybe associated with an asymmetric one. However, he considered that although this is a useful calculation, it cannot be reliably used to distinguish between the two conditions, as studies have shown that a significant minority of microcephalic neonates have normal HC/AC ratios.
49. In this regard, the Den Hollander et al report in Ultrasound Obstetrics & Gynaecology: the official journal of the International Society of Ultrasound in Obstetrics and Gynaecology 2000, entitled "Congenital microcephaly detected by prenatal ultrasound: genetic aspects and clinical significance", which analysed 30 fetus with prenatally diagnosed microcephaly, (defined as those with a head circumference more than 3 standard deviations below the mean), observed that 66% had normal HC/AC ratios.
50. In the event that there is sufficient evidence of microcephaly from the ultrasound scans, then further investigations are required, which is likely to include further ultrasound scans for other associated fetal abnormalities, and may include MRI. In the event that microcephaly is diagnosed, then because of its untreatable nature and its association with developmental delay, termination of the pregnancy can be offered to parents.
51. At page 17 of his original report, Mr Taylor provided a chart showing the measurements of Matilda's head circumference as recorded in the ultrasound reports between 21 – 35+1 weeks' gestation, together with his assessment of the standard deviation from the mean, and a description of the centiles, which they represent. He indicated that the measurements recorded on the 3^rd scan were normal, and that those on the 4^th scan gave no concern relating to fetal abnormality. Although he considered that, because of the slowing down in the estimated fetal weight between those two scans, the claimant's next scan ought to have been at 27 weeks' gestation, he accepted that leaving this to 30 weeks' gestation, as arranged by Mr Sau, fell within the range of responsible practice.
52. However, Mr Taylor was of the opinion that the recorded measurements on the 5^th scan required further action to be taken by Mr Sau, other than arranging for the next scan at 34 weeks' gestation, namely either a referral to tertiary level care, or at the very least a further ultrasound scan at 32 weeks' gestation, which would have resulted in the earlier recognition of the further evidence of microcephaly which would have been likely to have been present at that time. This was because, although the HC/AC ratio was within the normal range, the head circumference measurement had reduced from the 30-40^th centile at the 3^rd scan, to on or below the 3^rd centile at the 5^th scan, and, by his calculation, this represented a reduction from 1 standard deviation from the mean at the 3^rd scan, to between 3 and 4 standard deviations below the mean at the 5^th scan. Therefore, it was wrong for Mr Sau to have reported that there was normal interval growth, and Mr Taylor considered that the lack of referral, or further ultrasound scanning at 32 weeks' gestation, amounted to substandard care.
53. In relation to the 6^th scan, Mr Taylor noted that this was not in fact carried out until 35+0 weeks' gestation. However, he considered that its results had been correctly interpreted by the sonographer, as requiring, in the absence of Mr Sau, further assessment at King's College Hospital. This was because not only was the head circumference measurement indicated as being well below the 3^rd centile on both the bar chart and the growth chart, but, by his calculation, it was between 3 and 4 standard deviations below the mean. Moreover, mild ventriculomegaly had been correctly noted.
54. Mr Taylor noted that, although Miss Abdo-Nassri had measured the head circumference to be slightly larger at the 7^th scan, namely 287mm, this was still indicated, on both the bar chart and growth chart, as being less than the 3^rd centile, and, by his calculation, between 3 and 4 standard deviations below the mean. Moreover, although Miss Abdo-Nassri had measured the posterior ventricle to be slightly smaller, namely 9.5mm, not only did Mr Taylor consider this measurement to be inaccurate, but, in any event, the ventricle was still disproportionately large when considered in the context of the fetus having a very small head. Indeed, the Vp/H measurement was above the 97.5^th centile. In these circumstances, Mr Taylor considered that Miss Abdo-Nassri ought to have recognised these features as being sufficient evidence of microcephaly to have required further focused assessment, with a view to informing the claimant about the associated risks.

Mr David Howe

55. Mr Howe is a Consultant in Feto-Maternal Medicine based at the Princess Anne Hospital in Southampton, where he provides tertiary level care for women with complex pregnancies. Following his consideration of the claimant's obstetric records, he provided an initial report dated 17^th December 2015, and thereafter contributed to joint reports with Mr Taylor, dated 14^th August 2016 and 4^th October 2016.
56. In his review of the ultrasound scans, Mr Howe noted that the report of the 2^nd scan stated that the risk of Down's syndrome was lowered, albeit he was unable to locate the actual result of the assessment.
57. He noted that the 3^rd scan carried out by Andrew Zavos, whom he assumed to be a sonographer, reported the presence of a single umbilical artery and bilaterally dilated anterior horns. However, although the former of these was subsequently confirmed, when Mr Sau looked at the measurements on the ultrasound data base, he found the measurements of the lateral ventricles to be within the normal range.
58. Mr Howe noted that when Mr Sau carried out the 4^th scan, instead of using the anatomy template, he used the growth template. However, Mr Sau had reported that there were no structural abnormalities, and that the measurements recorded for the ventricular diameters were within the normal range. Mr Howe noted that the growth chart showed that, although the fetal head circumference was smaller than average, it showed normal growth from the previous scan.
59. Mr Howe considered that the measurements recorded at the 5^th scan showed that the fetus had grown appropriately, and that whilst the head circumference was on the 3^rd centile on the growth chart, the abdominal circumference was at a slightly higher centile. The estimated fetal weight was within the normal range, and that it was reported that the measurements for both the umbilical artery Doppler and liquor were within the normal range.
60. Mr Howe, noted that the growth chart for the 6^th scan showed the head circumference below the 3^rd centile. He stated that this tail-off in fetal growth, with estimated fetal weight also being below the 3^rd centile, had been recognised by Dorothy Speddings. As had various other additional concerns, including increased resistance in the umbilical artery Doppler, albeit it was within the normal range. The abdominal circumference and femur growth had also slowed and were both only just above the 3^rd centile. She also noted a slightly dilated third ventricle in the brain, and marginal insertion of the umbilical cord into the placenta. As a result of these matters, she referred the claimant for assessment at the tertiary medicine centre at King's College Hospital.
61. Instead, on the following day, the claimant was scanned by Miss Abdo-Nassri. The results which she obtained in this 7^th scan were considered by Mr Howe to be very similar to the previous day's results, albeit there was a longer femur length and the posterior horn measurement was 9.5mm, as opposed to 10.3mm. Miss Abdo-Nassri noted that the fetus had a small head, but considered the liquor and Doppler measurements to be satisfactory, and arranged for a further scan to take place in two weeks. Mr Howe also noted that Miss Abdo-Nassri thought that an MRI of the fetal brain might be considered postnatally.
62. Mr Howe noted that the fetal measurements obtained in the 8^th scan remained small, but that the interval growth was considered to be appropriate. The posterior horn measurement was 9.0mm, and he noted that Mr Sau did not arrange for any further scans in the fetal medicine department.
63. However, as a result of concerns about the claimant's blood pressure a 9^th scan was carried out, and, as was appropriate, Mr Howe noted that whilst the fetus was not re-measured, the liquor and Doppler were assessed.
64. The 10^th scan took place at 39+3 weeks'' gestation, and Mr Howe stated that it was clear from the growth charts, that the growth of both the head and abdomen circumferences had slowed, and the estimated fetal weight was only 1954g. Although, the umbilical artery Doppler showed positive end-diastolic flow, resistance was above the 95^th centile, and the liquor was at the low end of the normal range. As a result of which the claimant was admitted for induction.
65. Mr Howe stated that Matilda was born small, and that her subsequent growth has remained slow. She was noted to be dysmorphic at birth, and ultrasound scans carried out within a few days of birth reported as showing mildly dilated ventricles. Chromosome testing was negative. However, an MRI scan, carried out on 16^th September 2010, showed generalised cerebral atrophy, reduced white matter volume, and delayed myelination, but no structural abnormalities which might have been apparent antenatally.
66. Mr Howe stated that whilst it is possible to detect many fetal abnormalities during routine screening, the overall detection rate is 50%. Moreover, in the great majority of cases microcephaly only becomes apparent in late pregnancy, as the head growth falls compared with normal, with the effect being accentuated by continuing slow growth after birth in many affected children.
67. He considered that the majority of the abnormalities which Matilda exhibited postnatally would not have been apparent on antenatal ultrasound examination. Moreover, although her abnormal finger position may have been detectable, failure to do so would not be considered to be substandard medical care, as this is subtle and difficult to see. In so far as the ventricles are concerned, their growth trajectory may alter over the course of the pregnancy. In the present case although early on the ventricles were described as being enlarged, no diameters were recorded. Moreover, the later ventricular measurements showed only borderline enlargement. In that a measurement of less than 10mm would be considered normal, and here the measurements ranged from 9.0 – 10.3mm; such that even the latter measurement would only be considered to be slightly enlarged.
68. Mr Howe stated that only two possible anomalies were reported in the course of the 3^rd scan, which was a routine anomaly scan. Firstly, a single umbilical artery, and secondly, ventriculomegaly. In relation to the former, if it is the only abnormal feature, then it may be associated with later intrauterine growth restriction. Albeit, it may also be associated with a number of fetal abnormalities, including chromosomal ones, such that there is a need to examine the fetus with particular care for the presence of other anomalies.
69. Mr Howe stated that ventriculomegaly is the enlargement of the lateral cerebral ventricles, and is recognised when the posterior horns measure more than 10mm, and adverse outcomes are comparatively worse when the measurement is more than 12mm.
70. Mr Howe noted that the measurements recorded at the 3^rd and 4^th scans were within normal limits. He stated that although the better of the two measurements recorded in the 6^th scan exceeded 10mm, in that it was in a better plane than the other one, the callipers had not been correctly placed in relation to the ventricular wall, such that there will have been some overestimation in the measurement of 10.3mm.
71. He stated that the measurements carried out by Miss Abdo-Nassri on the following day were both in the correct plane. However, in the larger of the two measurements, 9.9mm, there was some overestimation due to the calliper having been placed on the wrong side of the ventricular border, whereas in the smaller of the two measurements, 9.5mm, the calliper was correctly positioned, such that it is more likely to be accurate. In any event, it was pointed out that, as both the latter measurements are less than 10mm, it was reasonable for Miss Abdo-Nassri to conclude that there was no ventriculomegaly.
72. Furthermore, even if there was ventriculomegaly at this stage, as it was only borderline, the great majority of the fetus would have had a normal outcome, and this is what the claimant would have been advised.
73. Mr Howe stated that microcephaly would not be suspected unless, "unless there was both a head circumference more than three standard deviations below the mean coupled with a disproportionate fall in head size compared with other fetal measurements."
74. In relation to the first of these criteria, he stated that if the fetal head circumference was below the 3^rd centile, then this would only indicate that the head circumference was 2 standard deviations below the mean.
75. In relation to the second of these criteria, he stated that disproportionate head growth is normally recognised by examining the HC/AC ratio. Where microcephaly is present, the HC/AC ratio is normally lower, due to the presence of a specific problem with head growth. Whereas, with a fetus with poor placental function, the HC/AC ratio is normally higher, as the fetal blood is diverted away from the liver, to the brain. In the present case, he set out Matilda's recorded HC/AC ratios in tabulated form on page 21 of his initial report, and concluded that at no point was her HC/AC ratio lower, and that after being nearly average at the date of the 5^th scan, thereafter it became progressively higher. He concluded that this pattern was more suggestive of a baby with poor placental function, and did not indicate the presence of microcephaly.
76. On this basis, Mr Howe did not consider that microcephaly should have been identified at the time of the 5^th scan, as the head circumference was only slightly below the 3^rd centile, (having been "just above" the 3^rd centile at the previous two scans), and the HC/AC was normal. On this basis there was no indication for referral for further assessment at tertiary level.
77. In relation to the 7^th scan, although Mr Howe acknowledged that there had been a further fall in the head circumference centiles since the 5^th scan, he noted that this had been matched by a similar fall in the other fetal measurements, such that there was no disproportionate reduction in HC/AC so as to indicate the presence of microcephaly, rather there had been an increase which favoured the conclusion that the fetus was small due to poor placental function. Furthermore, there was no evidence of ventriculomegaly, and therefore no indication for referral for further assessment.

Joint report

78. Both doctors were of the opinion that because of its association with developmental delay, where microcephaly is detected or suspected antenatally, a careful search for associated abnormalities is required to be carried out, and, even where none are found, if microcephaly is detected, then parents are required to be informed about the associated risks.
79. In so far as the antenatal detection of microcephaly is concerned, Mr Taylor maintained the opinion which he had provided in his earlier report, and concluded that where, as here, there was evidence that the fetus had a very small head which appeared to be getting smaller, together with brain abnormalities, then this raised the suspicion of the presence of microcephaly. However, Mr Howe stated that although some academic studies have used the definition 2 standard deviations from the mean to define microcephaly, because there is no difference in postnatal outcomes in such cases, the more commonly used definition is 3 standard deviations below the mean. Moreover, even where the head circumference was 3 standard deviations below the mean, in the absence of a disproportionately small HC/AC ratio, microcephaly would not be indicated.
80. It became clear during the course of their joint discussions, that whereas Mr Taylor had seen both the growth charts and the bar charts which were produced during the course of the ultrasound scans, Mr Howe had only seen the former. Therefore, Mr Taylor sent copies of the latter to him. They pointed out that, unlike the bar charts, because the growth charts showed where both the previous measurements and the instant one fell on the graph, one was able to assess, not only where the instant measurement fell on the graph, but also the trend in growth over time. Mr Howe pointed out that the clinician would only be able to assess the trend in growth from the bar chart, if he reviewed the bar charts from the previous scans. Mr Taylor agreed with this, but pointed out that the previous bar charts were available to the clinician on the Astraia system. The doctors agreed that, when considering the issue of fetal growth trends, a fall in a fetal measurement from a higher to a lower centile, (e.g. from the 50^th to the 15^th centile), will cause more concern, than if the measurements remain around the same centile, (e.g. the 15^th centile). It became clear that whereas the head circumference growth charts were based on the data from the study by Chitty et al, Charts of fetal size: 2. Head Measurements, in the British Journal of Obstetrics Gynaecology,1994, those for the bar charts were based upon the data from the study by Snijders et al, Fetal biometry at 14 – 40 weeks' gestation, in Ultrasound in obstetrics and gynaecology: the official journal of the International Society of Ultrasound in Obstetrics and Gynaecology,1994.
81. Just as Mr Taylor had produced a chart table showing measurements of Matilda's head circumference as recorded on the ultrasound reports between 21 – 35+1 weeks' gestation, so too did Mr Howe at page 6 of the joint report; albeit the precise arithmetic in the latter was revised in the additional report dated 4^th October 2016. It was apparent from this, that in so far as standard deviations from the mean were concerned, there were some differences between Mr Howe's table, and that previously produced by Mr Taylor. It became clear that whereas Mr Howe's table was based upon the data in Table 7 in the Chitty et al study, Mr Taylor's table had used the data in Table 2. Mr Taylor acknowledged that the more appropriate data was that provided in Table 7, such that for the purposes of assessing the significance of standard deviations from the mean, Mr Howe's report was to be preferred. Moreover, it also became apparent that Mr Taylor's table had incorporated an assessment of centiles from both the growth charts and the bar charts.
82. Although published tables were not available showing centiles and standard deviation of neonatal measurements, it was agreed that both Matilda's head circumference and birthweight were below the 0.4^th centile, and 4 standard deviations from the mean. Mr Taylor stated that in view of the small numbers of the population who would be born with such a head circumference, Matilda's head was extremely small at birth.
83. In relation to the 4^th scan, both doctors agreed that the head circumference measurements were within the normal range.
84. In relation to the 5^th scan, Mr Howe acknowledged that there had been a slight slowing of growth of the fetal head, but as this was accompanied by a similar degree of slowing of the abdominal circumference and estimated fetal weight, this suggested that the cause was generalised intrauterine growth restriction, rather than microcephaly. Moreover, as the head circumference was only 2 standard deviations below the mean, this did not meet the most commonly used definition for microcephaly. Although he acknowledged that the generalised slowing of growth was an indication for further ultrasound scans to be undertaken, with a view to looking for more evidence of slowing of growth, he considered that as the head circumference centile on the growth chart had fallen from just above the 3^rd centile to just below, it was reasonable for Mr Sau to report that there had been normal interval growth. Moreover, he stated that a clinician would use the growth charts, rather than the bar charts to assess growth velocity.
85. On the other hand, Mr Taylor noted that the head circumference had deteriorated to the 3^rd centile, and met the accepted definition of microcephaly being 2 standard deviations below the mean. Moreover, the trend of growth suggested that at birth the head circumference would be 3 – 4 standard deviations below the mean. He was of the opinion that whereas growth restriction could have been the explanation for the deterioration in head circumference, the possibility of microcephaly should also have been considered. In this regard, he pointed out that growth restriction and microcephaly are not mutually exclusive, and that it was not reasonable to rely upon a lack of disproportionality in the HC/AC ratio to rule out the presence of microcephaly. He pointed out that if Mr Sau had reviewed the bar charts, he would have been able to see that there had been a deterioration in head circumference centiles from about the 30^th to the 3^rd centile. In these circumstances it was unreasonable for Mr Sau to report that the head circumference remained at the 3^rd centile with normal interval growth.
86. In relation to the 6^th scan, Mr Howe accepted that the head circumference growth had slowed further since the previous scan. However, there had been slowing of the other fetal measurements, and the HC/AC ratio suggested comparatively greater slowing of the abdominal circumference. He pointed out that on the graph in the study by Den Hollander et al, relied upon by Mr Taylor to show that a significant proportion of fetus have normal HC/AC ratios, all but one of the cases had a ratio below the mean, and none approached the 95^th centile. Mr Howe again pointed out that the ventricle measurements had not been correctly measured, and overestimated the true measurement. However, having obtained the results which she did, the sonographer took the correct course of action by asking for a repeat ultrasound scan by a fetal medicine consultant.
87. Mr Taylor pointed out that the head circumference measurements obtained from the 6^th scan showed, on both the growth chart and the bar chart, that it was well below the 3^rd centile. Moreover, the table produced by Mr Howe showed that it was 3.11 standard deviations from the mean. In which case not only did this meet the accepted criteria for microcephaly, but it confirmed the downward trend from the previous scans, which, if it continued, was likely to mean that Matilda's head circumference would be at or near to 4 standard deviations from the mean at birth. Mr Taylor again pointed out that a reduced HC/AC ratio was not a pre-requisite for the presence of microcephaly, and that in any event there was disproportionate fetal growth between the head circumference and the femur length. He again referred to the table provided in the study by Den Hollander et al, and pointed to the number of cases of microcephaly where the HC/AC ratio was within the normal range.
88. He also observed that there is no evidence from the scan reports that any of the clinicians took into account the results of the HC/AC ratios. Indeed, the HC/AC ratio was only available on the bar chart screen, none of which, appeared to have been printed-off by any of them. He also pointed out that neither of the HC/AC ratios, obtained in 6^th or the 7^th scans approached the 95^th centile, but appeared on the bar chart to be around the 50^th and 70^th centile respectively. Mr Taylor stated that the HC/AC ratios provided by the scans were not significantly raised, and therefore did not support a diagnosis of growth restriction, as opposed to microcephaly. Moreover, the normal results of both the umbilical artery dopplers, and liquor volume failed to support a diagnosis of growth restriction.
89. In so far as the ventricle width was concerned, Mr Taylor repeated his view that Dorothy Speddings' measurement was likely to be more accurate than that of Miss Abdo-Nassri on the following day. In the circumstances, Mr Taylor agreed that Dorothy Speddings had taken the correct course of action by asking for a repeat ultrasound scan by a fetal medicine consultant.
90. In relation to the 7^th scan, Mr Howe repeated his view that the ventricle measurement carried out by Miss Abdo-Nassri should be preferred, which estimated the ventricle width to be 9.5mm, and therefore within the normal range. Moreover, that measuring the ventricular atrium is the recommended method of assessing ventricular size, and that the ratio between the ventricular and hemisphere measurements has not been the standard assessment for many years. He considered that as all the fetal measurements had slowed, this suggested overall growth restriction. He stated that the HC/AC ratio was on the 95^th centile, which suggested that the head was disproportionately large, which was the opposite to what would be expected in the presence of microcephaly. Moreover, the head circumference was only 2.1 (chart shows that it was 2.6) standard deviations from the mean, such that microcephaly should not have been diagnosed. The only action which the measurements required was the arranging for a further growth scan, which is what was done.
91. Mr Taylor, pointed out that in addition to preferring Dorothy Speddings ventricular measurements, it was a matter of common sense that the significance of any ventricular measurement may vary, depending upon the size of the fetus' head. Hence the widespread use of the Vp/H ratios in fetal medicine. He stated that in the present case the fetus had a very small head, which enhanced the significance of the slightly enlarged ventricular measurement, such that ventriculomegaly was evident. He stated that references to other fetal measurements was not particularly helpful in this case, as it provided a mixed picture. On the one hand although there was some evidence of a raised HC/AC ratio, it was not particularly high at the 50^th or 70^th centile, and on the other hand, the HC/FL ratio was very low. The most significant feature was that over the course of the ultrasound scans, the head circumference showed a reducing growth rate, from 1 standard deviation below the mean at the 3^rd scan, to 2 standard deviations below the mean at the 5^th scan, and 2 to 3 standard deviations below the mean at the 6^th/7^th scans.
92. Mr Taylor was of the opinion that given the context of the presence of a single umbilical artery, the presence of ventriculomegaly and the head circumference measurement having met the criteria for microcephaly, Miss Abdo-Nassri should have referred Matilda for further focused ultrasound scans and/or MRI, due to the risk of brain abnormality; a matter which she appears to have recognised given her view that at birth consideration may have to be given to a brain MRI.

Expert Evidence

Mr Myles Taylor

93. Mr Taylor agreed that, although he and Mr Howe had been able to calculate the standard deviations from the mean which the head circumference measurements represented, this would not be done in clinical practice, and instead the clinician would seek to assess this from the scan results. He said that the main reason why he considered that the risk of microcephaly should have been recognised, prenatally, was because of the fact that Matilda's head was small and getting smaller during the course of the pregnancy. He said that it was inappropriate for Mr Sau only to have had regard to the growth charts, and that the bar charts should also have been taken into account. He considered that Mr Sau's reliance upon the HC/AC ratios in his evidence was unfounded, and, in any event, there no evidence from the scan records that Mr Sau had relied upon the HC/AC ratios as giving him reassurance that there was no risk of microcephaly at the time.
94. In cross-examination he agreed that the Den Hollander et al study used a prenatal test of at least 3 standard variations below the mean for microcephaly, and that the Chervenak et al study, "The diagnosis of Fetal Microcephaly", in The American Journal of Obstetrics and Gynaecology, 1984, pointed out that when the criterion of at least 2 standard deviations below the mean was used, the association with mental retardation was inconsistent. However, he said that only using the criterion of at least 3 standard deviations below the mean, risked missing cases of microcephaly where the head circumference measurement was at least 2 standard deviations below the mean.
95. Mr Taylor said that the opinion which he expressed in his original report that microcephaly was present at the 5^th scan was not simply based upon the number of standard deviations below the mean which the head circumference measurement represented, but relied upon the diminishing growth velocity which this represented; the key issue, which wasn't sufficiently considered, being what the head circumference would be at birth. In this regard he reiterated that, unlike standard deviations from the mean, normal head growth should continue along the same centile throughout gestation.
96. It was pointed out to him that, although the bar charts from the 3^rd and 4^th scans may appear to show head circumference measurements between the 40^th – 30^th centiles, the centiles in Table 1 in Mr Howe's report showed the centiles to be between the 11^th – 6^th centiles. Mr Taylor agreed, but pointed out that the bar charts are based upon the data in study by Snijders et al, whereas Table 1 and the growth charts are based upon the data in the study by Chitty et al. Moreover, not only should a clinician take into account both the growth charts and the bar charts, but they both show the same pattern of diminishing head growth.
97. Mr Taylor said that the factors which ought to have triggered a referral to tertiary level care at the 5^th scan was that, in the context of a single umbilical artery and a diminishing head growth velocity, the head circumference was below the 3^rd centile. He agreed that intrauterine growth retardation was another possible cause for Matilda's head being small, but that these conditions were not mutually exclusive, and it was unreasonable, if this is what occurred, for Mr Sau to have assumed that, on this basis, microcephaly was not present at that stage.
98. He said that with either condition, the fetal measurements may provide a symmetrical or asymmetrical pattern of growth retardation, and therefore a clinician cannot make a diagnosis on the basis of the HC/AC ratio. In any event, Mr Taylor said that classically, intrauterine growth restriction is associated with abnormal umbilical artery Doppler readings, and none were present in this case.
99. Mr Taylor said that the condition known as ventriculomegaly, which involves the enlargement of the lateral ventricles within the brain, is caused either by blockage and associated dilation, or by brain shrinkage and relative enlargement of the ventricles. He agreed that the ventriculomegaly is normally considered to be present when the width of the lateral ventricle is over 10mm, and, even then, it is not considered to be severe until the atrial width is over 15mm. However, he said that this measurement has to be considered in context, and the significant factor in the present case was the relatively small head circumference. In these circumstances it was also necessary to take into account the Vp/H ratio, which had in fact been recorded in this case at the 3^rd and 4^th scans. Mr Taylor agreed that it wasn't necessary to obtain the latter measurement at each scan. However, where, as here, the ventricular width had been measured as being above 10mm at the 6^th scan, he considered that it was necessary for Miss Abdo-Nassri to have obtained the Vp/H ratio at the 7^th scan, regardless of the fact that her own measurement of the atrial width had been below 10mm, namely 9.5mm. He said that to ignore the possibility that ventriculomegaly was present in these circumstances would be dangerous, given the associated risks which it involved.
100. He agreed that none of the professional guidelines or academic studies which were before the court required the Vp/H to be obtained, and instead relied upon measurement of the ventricular width. However, he said that the guidelines in the 2007 Ultrasound in Obstetrics & Gynaecology, "Sonographic examination of the fetal central nervous system: guidelines for performing the 'basic examination' and the 'fetal neurosonogram'", produced by the International Society of Ultrasound in Obstetrics & Gynaecology, was for sonographers, rather than fetal medicine consultants, and that he considered that, given the borderline ventricular width measurements which had been obtained at both the 6^th and 7^th scan, in the context of the fetus having a very small head, no responsible clinician would have failed to have obtained the Vp/H ratio at the 7^th scan. Moreover, if Miss Abdo-Nassri had done so, then this would have provided grounds for suspicion of the presence of ventriculomegaly, as the ratio was above the 97.5^th centile.
101. Mr Taylor agreed that, on reviewing the scanned image, Dorothy Speddings second measurement of 10.3mm slightly exaggerated the ventricular width, as the higher calliper had been placed slightly too high on the scanned image, and that her first measurement of 9.9mm was more accurate. In relation to the measurements obtained by Miss Abdo-Nassri, he considered that on the first image the callipers were placed slightly too low, and on the incorrect plane, thus slightly underestimating the measurement of 9.5mm, but he agreed that on the second image the callipers had been placed slightly too high, thus slightly overestimating the measurement of 9.9mm.
102. Overall, Mr Taylor said that in the context of a very small head, below the 3^rd centile, and poor growth trajectory, having obtained ventricular width measurements of around 10mm, it was unreasonable not to have suspected the presence of ventriculomegaly. He agreed that none of the academic papers before the court suggested that the 10mm ventricular width criterion should be reassessed in the context of a small head, but stated that it followed from the nature of the condition, namely that one of the causes may be brain shrinkage and relative enlargement of the ventricles.
103. He reiterated that neither normal, nor high HC/AC ratios should have given any reasonable fetal medicine consultant reassurance that microcephaly wasn't present. Moreover, the presence of normal liquor and umbilical artery Doppler, would be contra-indications that the fetus' small head was due to intrauterine growth retardation. Therefore, at the 7^th scan the claimant ought to have been referred to tertiary level care, where she would have been likely to have benefitted from multidisciplinary assessment.
104. Mr Taylor agreed that at the 8^th scan the ventricular width of the posterior horn was measured at 9mm, and the Vp/H was within the normal range. However, there was little indication that at this stage the fetus' very small head was due to intrauterine growth restriction, as, if this was the case, you would expect to see abnormality in both the liquor volume and umbilical artery Doppler, which were both normal. He said that the first time when these measurements had been found to be abnormal was at the 10^th scan, when it was noted that there had been no fetal growth since the previous scan.
105. He agreed that at birth, Matilda had a very small head and a small body. However, he said that this did not rule out the presence of microcephaly, as if the latter was present, then whatever had been causing it, may also have caused Matilda to have a small body. Moreover, she had dysmorphia, which had nothing to do with any pre-existing intrauterine growth restriction.

Mr David Howe

106. Mr Howe agreed that the opinions which he had expressed in his original report had been based on the scan reports and growth charts, and that it was only during the course of the joint meeting that he had appreciated that he had not had sight of the bar charts. He said that regardless of this, his opinions had not altered, as he considered that the fetal growth velocity is best assessed from the growth charts. Moreover, he said that although it was apparent that the clinicians at Lewisham Hospital were able to view all of the bar chart data from the previous scans recorded on the Astraia system, it would not be necessary for them to do so, as the computer automatically records the previous data on the growth charts. He said that it should also be borne in mind that the clinician would be able to view the growth charts on the computer screen, which would provide a significantly enlarged image of the charts, and would consequently be able to make a clearer assessment of the growth trajectory than is able to be obtained from the smaller printed images contained within the scan records.
107. He agreed that, as a clinician, one wouldn't use the criterion of standard deviations below the mean in order to assess whether microcephaly may be present. Instead, the clinician would assess how far below the 3^rd centile the head circumference measurement was on the growth chart, as 1.88 standard deviations below the mean is represented by the 3^rd centile itself. Therefore, it would be a matter of clinical judgment as to whether the head circumference measurement was sufficiently below the 3^rd centile to cause concern that the fetus was microcephalic.
108. Mr Howe agreed that there are a number of different possible causes of fetal growth restriction, including chromosomal or genetic ones, and that where these are the operative cause, the fetus may be either symmetrically or asymmetrically affected, such that the HC/AC ratio will not be a reliable indicator of such a cause. However, he said that bearing in mind the results of the 2^nd scan, it was most unlikely that a head circumference measurement around the 3^rd centile would be due to a chromosomal or genetic disorder. On the other hand, placental insufficiency as a possible cause was supported by the higher HC/AC ratio.
109. He agreed that it was significant that neither the growth charts nor the bar charts provided for exact centile measurements below the 3^rd centile, and that any measurement below the 3^rd centile requires to be assessed very carefully, as it may indicate that the fetus is at risk.
110. Mr Howe agreed that the presence of a single umbilical artery may be associated with chromosomal abnormalities. However, he said that in the absence of any other structural abnormality, there is no increased risk of chromosomal disorder. He said that although the other structural abnormalities listed in the study by Lubusky et al, "Single umbilical artery and its siding in the second trimester of pregnancy: relation to chromosomal defects", in Prenatal Diagnosis, 2007, included both ventriculomegaly and small for gestational age, the latter condition was a very unusual one, relating to a fetus under 16 weeks' gestation, which didn't apply in the claimant's case. He said that late onset growth restriction, as in the present case, gives rise to a very small risk of chromosomal disorder.
111. He said that in the present case it appeared that the claimant had undergone two anomaly scans. He agreed that when carrying out the second of these, the 4^th scan, Mr Sau hadn't used the anomaly template, which, he eventually agreed, revealed poor practice, but not such as would be outside the range of a reasonable doctor. Moreover, if Mr Sau's evidence is correct, a matter which appears to be supported by the scan report, then he carried out all of the necessary examinations for the ascertainment of structural abnormalities which were required in 2008, and found none. He agreed that if Mr Sau hadn't carried out a sufficient examination for anomalies at the 4^th scan, then this would have been a breach of his professional duty of care, as he wouldn't have been able to exclude the increased risk of chromosomal disorder resulting from a single umbilical artery, because he hadn't been able to exclude the presence of other structural abnormalities. However, if he had carried out a sufficient examination for anomalies, then the remaining risks from the presence of a single umbilical artery, are intrauterine growth disorder and still birth.
112. Mr Howe's explanation for why the head circumference measurement on the scanned image is recorded as 192mm, whereas it has been entered on the Astraia system as being 197mm, was because, whilst carrying out the 4^th scan, Mr Sau may have re-measured the fetal head circumference, and, whilst inputting the corrected measurement on the Astraia system, forgotten to enter it on the scanned image. He said that this was something which he had done on occasions.
113. Mr Howe agreed that the head circumference measurement at the 5^th scan being below the 3^rd centile was within the "danger zone." However, having already carried out an anomaly scan, the only remaining risk which had to be considered was that of intrauterine growth restriction. He agreed that both the liquor volume and umbilical artery Doppler was normal, but said that not only were these features which tended to become abnormal at a later stage of the pregnancy, but that the fetus not severely growth restricted. In any event, the head circumference measurement had to be viewed in the context of a normal HC/AC ratio, and an expected fetal weight measurement within the normal range.
114. Mr Howe said that having carried out the 5^th scan, he would probably have arranged for the next scan at 33 weeks' gestation. However, he didn't believe that arranging for it to be carried out at 34 weeks' gestation was inappropriate, and other doctors would have done so.
115. He said that Dorothy Speddings appears to have been concerned about the slowing down of all the growth parameters at the 6^th scan, which he considered to be consistent with intrauterine growth restriction. Moreover, the umbilical artery Doppler was abnormal. He said that he would not have considered that the fetus was microcephalic at the 6^th scan, firstly, because the head circumference wasn't more than 3 standard variations below the mean, and secondly, the head circumference was not disproportionately low compared to the abdominal circumference.
116. In relation to the latter criterion, having carried out a pre-hearing literature search, Mr Howe said that he was unable to find any other reference to this, other than that contained in the Study by Chervenak et al, which showed that although false positives occurred when head circumference measurements alone were taken into account, none occurred when the HC/AC ratio was considered. He said that the lack of reference to disproportionate growth in Fetal Craniospinal and Facial Abnormalities. High Risk Pregnancy Management Options, 3^rd Edition, 2006, was because this was an undergraduate text book; albeit he agreed that Chervernak was one of its authors. He agreed that there was no mention of a disproportionate growth requirement being considered in the study by Den Hollander et al, but said that they were not using the, standard deviation below the mean, criterion as the definition for microcephaly, only as a criterion for entry into the study. He also agreed that there was no mention in any of the scan records that the HC/AC ratio had been used by any of the clinicians, including Mr Sau, in order to rule out the possible presence of microcephaly, nor was there any mention that the clinicians considered that the explanation for the small head circumference measurements was due to placental insufficiency. However, he said that a clinician's reasoning isn't always included within the scan reports, and may be required to be deduced from the arrangements which are advised to be made for the patient's future care, which in the present case was consistent with the clinicians believing that they were dealing with a small but otherwise normal fetus.
117. He stated that it was of significance that despite Matilda's head circumference at birth being below 4 standard deviations below the mean, microcephaly wasn't diagnosed until the following year; albeit, Mr Howe agreed that Matilda would have satisfied the criteria for entry into the study by den Hollander et al. Moreover, the fact that her head circumference was disproportionately large, compared to her abdominal circumference during the pregnancy, tended to support the diagnosis of intrauterine growth restriction, rather than microcephaly.
118. Mr Howe said that if a head circumference of more than 3 standard deviations below the mean was the only criterion for microcephaly, then one would be advising far too many parents to consider abortion, because of the significant incidence of normal brain growth within such a group of fetus. He said that he would not anticipate any of the hospitals who refer cases to him, to have referred the claimant for tertiary level assessment, based upon the results of the 6^th scan, and no similar cases had been referred to him.
119. He said that the ventricular measurement obtained in the 7^th scan was more accurate than that obtained in the previous scan. He said that the 10mm ventricular measurement is the criterion for the presence of ventriculomegaly, and that anything below this measurement would not be considered to be abnormal. Mr Howe said that he didn't consider that it was appropriate to consider the head circumference measurement when making such a diagnosis, and had never done so; albeit he agreed that the Astraia system which was being operated at the Lewisham Hospital allowed the Vp/H ratio to be calculated, and that it had been during the 3^rd and 4^th scans in this case.

Discussion

The 1^st – 4^th ultrasound scans

120. At the commencement of the claimant's second pregnancy, save for a history of hypertension during the 3^rd trimester of the first pregnancy, there were no contra-indicators to its successful outcome, and the birth of another healthy baby. Indeed, this was confirmed when, as a result of the 2^nd ultrasound scan, nuchal translucency was found to be 1.8, indicating a low risk of the chromosomal disorder, Down's syndrome; in relation to which, it is apparent from the scan report, the claimant received appropriate advice.
121. The first potential contra-indicators were those reported by the ultrasonographer, Andrew Zavos, as a result of the 3^rd scan, namely the presence of a single umbilical artery, and bilateral dilated anterior horns.
122. The evidence relating to the potential significance of the presence of a single umbilical artery, rather than the norm of two such arteries, is that it may be associated with the presence of other fetal abnormalities, including chromosomal ones, and the risk of intrauterine growth restriction. As a result of the former of these possible associations, it is necessary to examine the fetus with particular care in order to ascertain whether there are any other structural abnormalities. Moreover, as a result of the latter of these possible associations, it is necessary to monitor the growth of the fetus, in order to ascertain whether it is suffering from intrauterine growth restriction. In the event that sufficient care has been taken to ascertain the presence of other structural abnormalities, and none have been found, then it appears to be agreed that there is no increased risk of the presence of a chromosomal or other disorder in the fetus.
123. As a result of the report of Andrew Zavos, which indicated not only the presence of a single umbilical artery, but also the presence of another structural abnormality, namely bilaterally dilated anterior horns, it was clearly appropriate, in accordance with the hospital's procedures, that an early review of his findings should take place by a suitably qualified clinician, namely a Fetal Medicine Consultant.
124. Originally there was no criticism made, either of Mr Sau's review of the earlier findings, or the manner in which he carried out the 4^th scan. However, although no criticism has been made of his review, (indeed its results have been confirmed by Mr Taylor), criticism has been levelled at Mr Sau, by those representing the claimant, firstly, arising out of the 5mm discrepancy between the recorded head circumference measurements entered onto the ultrasound scanner, and the Astraia system, and, secondly, for having used the growth template, as opposed to using an anomaly one, on the Astraia system.
125. In relation to the first of these criticisms, although I appreciate that Mr Sau's evidence gained some support from Mr Howe's own experience, I confess that I did not find Mr Sau's explanation, that he may have decided to check the initial head circumference measurement, and then omitted to enter it onto the scanner, to be entirely convincing. Whilst I do not find it particularly surprising that Mr Sau did not have any specific recollection of the matter, it seems to me at the very least surprising that, if he did have cause to believe that he needed to re-measure the head circumference, he did not enter the new measurement on the scanner, rather than just the Astraia system.
126. In relation to the second of these criticisms, it is queried whether Mr Sau carried out the scan with sufficient care so as to be able to ascertain whether there were any other structural abnormalities, in addition to the finding of the single umbilical artery. This being of significance, as Mr Howe acknowledged, because in the absence of a sufficiently careful examination, Mr Sau would not have been in a position to confirm that there were no other structural abnormalities.
127. Undoubtedly, as Mr Howe eventually agreed, the use of the growth template, as opposed to the anomaly template amounted to poor professional practice; the significance of which was that the growth template would not automatically prompt the operator to make all of the fetal measurements, which the anomaly template would do. However, Mr Sau is an experienced Fetal Medicine Consultant, and it is apparent from the scan report, that he was aware of the particular reason why he was carrying out the 4^th scan, namely to check for structural abnormalities, and stated that he found none; a conclusion which, at least in so far as the brain is concerned, was confirmed by Mr Taylor after his review of the images recorded during the 3^rd and 4^th scans. Indeed, the use of the phrase, "particularly the brain, kidneys and heart looked normal.", suggests that in addition to looking at these organs, he examined other structures within the fetus. Moreover, the results of his measurements of the lateral ventricles, namely that they were within the normal range, were in line with his earlier findings in relation to the results of these measurements at the 3^rd scan.
128. In these circumstances, I am satisfied that, despite the use of the wrong template, and the lack of the correction of the head circumference measurement on the scanner, Mr Sau did undertake a sufficiently careful examination during the 4^th scan, so as to be in a position to ascertain that, apart from the presence of a single umbilical artery, there was no other structural abnormality, and there were normal lateral ventricles.
129. Accordingly, I accept that, at this stage at least, as the only contra-indicator to a successful pregnancy was the presence of a single umbilical artery, with no other structural abnormality, the main focus of concern would have been upon the possible presence of intrauterine growth restriction, which required periodic growth scans to be undertaken. In that regard, although, in view of the reduction in estimated fetal weight between the 3^rd and 4^th scans, Mr Taylor makes some criticism of Mr Sau not having arranged for a repeat scan until 30 weeks' gestation, not only does nothing appear to turn on this, but Mr Taylor does not suggest that this is outside the scope of reasonable clinical practice.

Microcephaly

130. Unsurprisingly, a not inconsiderable amount of time was spent, during the course of the trial, upon the issue of the appropriate criteria for the diagnosis of microcephaly, with particular reference being made to the academic literature on the subject. Essentially, as the condition is characterised by an abnormally small head, caused by an underlying brain abnormality, it will not be diagnosed in the absence of a sufficiently small head circumference, as represented by the number of standard deviations below the mean.
131. Although Den Hollander et al used the criterion of 3 standard deviations below the mean, in order to determine the selection of fetus for their study, both Den Hollander et al, and Kalish et al, Fetal Craniospinal and Facial Abnormalities. High Risk Pregnancy Management Options. Third Edition ed. Saunders Elsevier; 2006, acknowledge that the criteria of a head circumference more than 2 standard deviations below the mean, and a head circumference more than 3 standard deviations below the mean, have both been used in the diagnosis of microcephaly.
132. Moreover, although Chervernak et al, acknowledge that using 3 standard deviations below the mean correlates better with the incidence of mental disability, they too acknowledge that the criterion of a head circumference more than 2 standard deviations below the mean has been used by others.
133. It seems to me that, when considering these matters, it is important to bear in mind that the question to be determined in this case is not whether the antenatal clinicians should have determined that the fetus was in fact microcephalic, but whether they were negligent in failing to appreciate that the fetus was at risk of suffering from microcephaly, thus requiring the claimant to be referred for further investigation and assessment at a tertiary level centre. In this regard, I consider that it is of significance that, despite Mr Howe's opinion that the condition would not be "suspected" unless, inter alia, the head circumference was more than 3 standard deviations below the mean, he did acknowledge that any head circumference measurement which was below the 3^rd centile, (the 3^rd centile representing 1.8 standard deviations below the mean), was in the "danger zone", and required to be assessed very carefully, as it may indicate that the fetus is at risk. Indeed, this view not only appears to reflect the fact that the lowest of the centile measurement lines on the Astraia system is the 3^rd centile, but is also reflective of the academic literature's ambivalence in relation to the diagnostic criteria for the presence of microcephaly.
134. In these circumstances, it seems to me that Mr Howe's original opinion, that microcephaly wouldn't even be "suspected" unless, inter alia, the head circumference measurement was at least 3 standard deviations below the mean, overstates the position. It may well be that a formal diagnosis of microcephaly would not be made without this criterion being satisfied. However, in the context of the issue to be determined at this stage of the litigation, and in the light of Mr Howe's acknowledgment, that a head circumference measurement below the 3^rd centile may indicate that the fetus is at risk, ( a matter which was also acknowledged by Mr Sau, who stated that a head circumference on or below the 3^rd centile raises possible concerns about the presence of microcephaly), I consider that Mr Taylor's view is correct, and that a head circumference at least 2 standard deviations below the mean, (as indicated by being below the 3^rd centile), amounts to some evidence, at least, that the fetus is at risk of suffering from microcephaly.
135. It is clear from the evidence of both experts, that although a sufficiently small head size is a pre-requisite to the formal diagnosis of microcephaly, a second significant factor which is required to be taken into account in relation to the assessment of whether a fetus is at risk of suffering from microcephaly, is fetal growth velocity. Indeed, this is the main reason why Mr Taylor considered that there was sufficient evidence that the fetus was at risk of suffering from microcephaly in this case, so as to require the claimant's referral to tertiary level assessment. As he explained, a progressively small head in centile terms over the 2^nd and 3^rd trimester is likely to meet the standard deviation below the mean diagnostic criteria for the condition, because unlike standard variations from the mean, normal head growth should continue along the same centile during gestation. He said that the significance of this factor in the present case, was that the decline in head growth velocity, as represented by the progressively decreasing centile positions of the head circumference measurements, indicated that, at birth, the head circumference was likely to meet the diagnostic criterion for the presence of microcephaly, of being more than 3 standard deviations below the mean.
136. Mr Taylor's evidence, that normal head growth should continue along the same centile during gestation, was not challenged on behalf of the defendant. Indeed, I note that in his initial report, Mr Howe acknowledged the potential relevance of fetal head growth velocity; hence his reference to the fact that, in the majority of cases, microcephaly only becomes apparent in late pregnancy, "….as head growth fails compared to normal…."; a matter which is also reflected in the experts' joint report, where they agreed that, "…...the finding that a particular fetal measurement is on the 15^th centile will cause more concern if it was previously noted to be on the 50^th centile compared to the case when it was always on the 15^th centile." In these circumstances, I am satisfied that, in addition to the head circumference measurement, head growth velocity is undoubtedly a matter which also requires to be scrutinised with care by those who were obliged to interpret the results of the antenatal ultrasound scans.
137. It would appear that a third factor which is of potential relevance to the determination of whether a fetus is at risk of suffering from microcephaly, is the comparative growth velocity of the other fetal measurement. In that although microcephaly arises where the abnormally small head, is caused by an underlying brain abnormality affecting its development, as Mr Taylor acknowledged in his report, a small head may occur as part of an overall growth restriction affecting other parts of the fetus. Indeed, he stated that this is the more common presentation. Mr Sau's unchallenged evidence being that whilst he sees a growth restricted fetus about 2 – 3 times a week, he sees a microcephalic fetus less than once a year.
138. It is because of these differential causes that ultrasound reports often include the calculation of the ratio between the fetal head circumference and the fetal abdominal circumference, so as to assist in distinguishing between an overall growth restriction, which may be characterised by a normal HC/AC ratio, and microcephaly, which may be associated with an asymmetric one, namely one where the head circumference is small compared to the abdominal circumference. Moreover, as Mr Howe explained, an asymmetric HC/AC ratio, where the head circumference is large compared to the abdominal circumference, may be associated with intrauterine growth restriction, due to the diversion of the fetal blood supply away from the liver to the brain.
139. However, Mr Taylor stated that, although the HC/AC ratio is a useful calculation, it cannot be reliably used to distinguish between the two conditions, as the same abnormality, which is causing the lack of brain development, may also cause a lack of development in other parts of the fetus. Indeed, he pointed out that in the Den Hollander et al study, a significant minority of microcephalic neonates had normal HC/AC ratios. This aspect of Mr Taylor's opinion was challenged on behalf of the defendant. In particular, Mr Howe was of the opinion that that microcephaly would not even be "suspected" in the absence, inter alia, of a disproportionate fall in head size as compared to the other fetal measurements.
140. I have considered this aspect of Mr Howe's evidence with care, and note that not only was there no challenge to Mr Taylor's opinion that the same abnormality, which is causing the lack of brain development, may also cause a lack of development in other parts of the fetus, but in cross-examination, Mr Howe appeared to acknowledge that, as fetal growth restriction, including chromosomally and genetically caused fetal growth restriction, may result in either symmetrical or asymmetrical growth, the HC/AC ratio will not necessarily be a reliable indicator as to its cause.
141. In these circumstances it seems to me that, once again, bearing in mind the Den Hollander et al study, and the proportion of cases in which microcephaly was detected, despite the HC/AC ratio being within the normal range, Mr Howe overstates the position. In that whilst the HC/AC ratio is undoubtedly a relevant factor, I do not consider that it can be said that the absence of a disproportionate fall in head size, compared to other fetal measurements, is a determinative one, in the absence of which microcephaly would not even be suspected. Indeed, I note that Mr Howe agreed in cross-examination that, beyond the lack of false positives found by Chervernak et al when the HC/AC ratio was used as a criterion rather than the head circumference measurement alone, there was no reference to a disproportionate HC/AC ratio being used in the diagnosis of microcephaly in the academic literature.

Clinical practice in the use of the Astraia system

142. A further matter which requires to be considered, both in relation to the assessment of how far below the 3^rd centile the various head circumference measurements represent standard deviations below the mean, and in relation to the assessment of fetal growth velocity, is which aspects of the data contained on the Astraia system ought, as a matter of clinical practice, to have been taken into account by those undertaking the ultrasound scans.
143. Mr Sau's evidence was that once he had input the fetal measurements into the Astraia system, he would press F7 and study the growth charts, without any reference back to the previous bar charts. To an extent, this practice was supported by Mr Howe, who stated that fetal growth velocity was best assessed from the growth charts. Mr Taylor was not critical of the use of growth charts in themselves. However, he was critical of Mr Sau for not having referred back to the bar charts, and pointed out that had he done so, then he would have been in a better position to appreciate the significance of the fall in head circumference measurements in this case.
144. I have little doubt that in the vast majority of cases, where no concerns arise from the position of the fetal measurement centiles on the growth charts, then there would be little need, if any, to refer back to the bar charts. In this regard, the growth charts are clearly designed to provide a graphic representation of growth velocity, and I appreciate that when the Astraia system is being operated, the ability to discern the centile measurements is facilitated by the use of the larger image displayed on the screen. However, it seems to me that, in the far smaller number of cases in which such concerns do arise, Mr Taylor is correct that there is no logical reason why a clinician would deprive him or herself from benefitting from the further potentially relevant evidence that is available from the bar charts, which are also retained on the Astraia system. Indeed, I note that Mr Sau's evidence cannot be entirely accurate on this point in any event, in that some of the data, in particular the HC/AC ratio, is not available on the growth charts, such that as part of his overall assessment of the fetal data, he is obliged to have regard to the bar charts.

The 5^th scan

145. Although the conclusion reached by Mr Sau in his report on the 5^th scan was that, "The HC remain at the 3^rd centile with normal interval growth.", he acknowledged in his evidence, that in fact, not only was the head circumference just below the 3^rd centile, but there had also been some slowing of growth. He sought to explain that he had recorded that there had been "normal interval growth", because there had been significant growth from the previous scan. Moreover, he stated that the reason why he didn't suspect the risk of microcephaly, was not only because a head circumference just below the 3^rd centile would not be considered to be microcephalic, but also because the head circumference measurement was above that of the abdominal circumference.
146. This view was endorsed by Mr Howe, who was of the opinion that the head circumference was only slightly below the 3^rd centile, having been "just above" the 3^rd centile at the two previous scans, and the HC/AC ratio was normal.
147. Mr Taylor disagreed with this opinion, not only because of the lack of reassurance which he considered could properly be obtained from a normal HC/AC ratio, but in particular because of the centile position of the head circumference at the 5^th scan, and the significant loss of growth velocity which was evident from the previous scans.
148. As I have already sought to explain, I do not feel able to accept the original opinion expressed by Mr Howe, that in the context of this case, where the issue is whether there was sufficient evidence to indicate that the fetus was at risk of suffering from microcephaly, one of the necessary criteria for suspecting the presence of microcephaly, was that the head circumference measurement was more than 3 standard deviations below the mean. In these circumstances, I consider that because the fetal head circumference at the 5^th scan was below the 3^rd centile, and therefore at least 2 standard deviations below the mean, there was, at least, some evidence that the fetus was at risk of suffering from microcephaly.
149. Furthermore, even if one disregards the more dramatic picture which emerges from the bar charts, and only has regard to the growth charts, I have considerable doubts concerning the accuracy of Mr Howe's description, that if the position of the head circumference measurement at the 5^th scan was only slightly below the 3^rd centile, the head circumference measurements at the earlier scans were "just above" 3^rd centile. Indeed, it is apparent from the Table which Mr Howe produced at page 6 of the joint report, that not only had the head circumference measurement at the 4^th scan been on the 6^th centile, but the head circumference measurement at the 3^rd scan had been on the 11^th centile. This being a substantially greater fall in growth velocity, than the "insignificant" reduction, which Mr Sau considered a fall from the 5^th to 3^rd centile, would have represented.
150. In these circumstances, even if one disregards the bar charts which disclosed a more dramatic reduction in head circumference growth velocity, I agree with Mr Taylor that a more significant picture of loss of head circumference growth velocity emerges from the growth chart, than appears to be encompassed by Mr Howe's description. Moreover, even with the inevitable increase in head circumference growth from the previous scan, it is extremely difficult to reconcile the position of the head circumference measurement centiles on the growth chart, with Mr Sau's conclusion, contained in his scan report, that there had been "normal interval growth."
151. Whilst I accept that it is necessary to take into account that, in the context of a single umbilical artery without the presence of another structural abnormality, the only remaining risk factor was intrauterine growth restriction, it is clear that not only was there no particular indication of this from the normal HC/AC ratio, (in contrast to an asymmetrical one where the head circumference was large compared to the abdominal one), but, for the reasons I have already explained, I do not consider that, in the presence of other evidence which indicated that a fetus is at risk of suffering from microcephaly, a normal HC/AC ratio would in itself be sufficient to provide sufficient reassurance that microcephaly ought not to be suspected.
152. Indeed, not only is there no indication, from Mr Sau's scan report, that it did provide him with any such reassurance, but, although I accept that not every contingency may be recorded in a scan report, I am afraid that, having listened and observed Mr Sau on this issue, I consider that his explanation that he did not suspect the risk of microcephaly because of the normal HC/AC ratio, appeared more likely to have been an ex-post facto rationalisation of his position, rather than a true reflection of his rationale at the time.
153. In the light of these matters, the question which requires to be determined is whether the fetal measurements obtained at the 5^th scan, as compared with those obtained at the earlier scans, provided sufficient evidence that no reasonable clinician in the position of Mr Sau would have failed to appreciate that, as at 30+1 weeks' gestation, the fetus was at risk of suffering from microcephaly, so as to require either referral for further investigation and assessment at a tertiary level centre, or at least to require a re-scan at 32 weeks' gestation.
154. This question has required me to re-consider, not only Mr Sau's explanation for arranging to re-scan the claimant at 34 weeks' gestation, but, in particular, the opinion of Mr Howe which, albeit refined, remained grounded in the significance of the lack of a disproportionately small head circumference, as compared with the other fetal measurements. As I have already indicated, not only did Mr Howe draw back from the determinative nature of this factor, but it is apparent that both Mr Howe and Mr Sau drew back from the determinative significance of a head circumference more than 3 standard deviations below the mean, when considering the issue of whether a fetus was at risk of suffering from microcephaly, as opposed to its requirement in relation to the diagnosis of the presence of the condition.
155. Ultimately, and bearing in mind these concessions, I am satisfied that in the context of the fetal measurements which had been taken at the various scans, including the 5^th scan, Mr Howe's support for Mr Sau's decision only to re-scan at 34 weeks' gestation, is unjustified. (Indeed I note that, although he didn't consider it evidence of clinical negligence, Mr Howe stated that he would have arranged to re-scan the claimant a week earlier, at 33 weeks' gestation). In this regard, I consider that not only does Mr Howe's opinion, and Mr Sau's decision, lack a sufficiently rational concern about the significance of the fetal head circumference being below the 3^rd centile at the 5^th scan, but in particular they lack such concern for the significant loss in head circumference growth velocity disclosed by the earlier scans.
156. In these circumstances, and as explained by Mr Taylor whose evidence on this point was supported by the academic literature and the rationale emanating from the scan measurements, I am satisfied that the evidence available to Mr Sau at the 5^th scan established that the fetus was at risk of suffering from microcephaly, and that no reasonable clinician should have failed to have recognised the need, either to refer the claimant for further investigation and assessment at a tertiary level centre, or at least to have arranged to re-scan her earlier than 34 weeks' gestation. If the only relevant factor had been that the head circumference was just below the 3^rd centile, then in the absence of any loss of growth velocity, and bearing in mind the normal HC/AC ratio, it may be that continuing to re-scan the claimant at normal intervals would have been acceptable. However, I am satisfied that in view of the additional factor of the significance of the loss of growth velocity from the previous scans, Mr Taylor is correct that there was sufficient evidence that the fetus was at risk of suffering from microcephaly that, at the very least, a rescan earlier than 35 weeks' gestation was required, namely one at 32 weeks' gestation.

The 7^th scan

157. The reason for the 7^th scan having taken place, was that on the previous day, when the 6^th scan was undertaken, the ultrasonographer, Dorothy Speddings, had found that all of the growth parameters had slowed down, the ventricles appeared mildly dilated, the posterior horns being recorded to be 10.3mm, (albeit reported as 10.2mm), and, although the Doppler examination of the umbilical artery demonstrated adequate EDF (end dystolic flow), the PI (pulsivity index) was close to the 95^th centile. In view of these findings, and bearing in mind the presence of a single umbilical artery, it was clearly necessary for the health of the fetus to be reviewed. It would appear that had Mr Sau been available, he would have carried out the review. Instead, the claimant was referred to King's College Hospital, which was the local tertiary level centre. However, on the following day, Miss Abdo-Nassri, one of the Fetal Medicine Specialists from the latter hospital, was running an outreach clinic at Lewisham Hospital, and so it was she who undertook the 7^th scan, when the claimant was 35+1 weeks' gestation.
158. Clearly the context in which the health of the fetus was required to be assessed at the 7^th scan had altered, since that of the 5^th scan, in that the apparent mild dilation of the posterior ventricles, taken in combination with the presence of a single umbilical artery, raised the possibility of other fetal abnormalities, including chromosomal ones. Moreover, the head circumference was even further below the 3^rd centile on the growth charts, which again required very careful assessment, in order to consider whether the fetus was at risk of suffering from microcephaly.
159. In view of the agreement that the accepted definition for the diagnosis of ventriculomegaly is where the width of the atrium of the lateral ventricle is greater than 10mm, some time was spent, during the course of the hearing, considering the various posterior ventricle measurements which were obtained respectively by Dorothy Speddings, 10.3mm and 9.9mm, and Miss Abdo-Nassri, 9.9mm and 9.5mm. On this point, I do not consider that much was gained from a consideration of the respective qualifications and experience of the two individuals. On the one hand Dorothy Speddings as a ultrasonographer is likely to operate the scanner more frequently, whereas Miss Abdo-Nassri, as a Fetal Medicine Specialist, is likely to have greater expertise in the interpretation of scans.
160. Although, in his initial report, Mr Taylor had stated that Dorothy Speddings' 10.3mm should be preferred to that of Miss Abdo-Nassri's measurement of 9.5mm, in cross-examination he accepted Mr Howe's opinion, that Dorothy Speddings' 10.3 measurement slightly exaggerated the ventricular width, as the higher calliper had been placed slightly too high on the scanned image. Thus her 9.9mm measurement was to be preferred. Moreover, although he considered that Miss Abdo-Nassri's measurement of 9.5mm slightly underestimated the ventricle width, in that the callipers were placed slightly too low, and on the incorrect plane, he again accepted Mr Howe's opinion, that her measurement of 9.9mm slightly overestimated the ventricle width, because the callipers had been placed slightly too high.
161. In these circumstances, and given the inevitable latitude for operator error, it seems to me that it is likely that the atrial width at this time was likely to have been somewhere between 9.5 – 9.99mm.
162. The significance of this conclusion is that the measurement failed to meet the accepted diagnostic definition of ventriculomegaly, which is the reason why Mr Howe concluded that there was no evidence that the fetus was suffering from the condition at the 7^th scan. However, although Mr Taylor had originally sought to rely upon the larger of Dorothy Speddings' measurements, it is apparent from his initial report that he also considered that the smaller of Miss Abdo-Nassri's measurements, 9.5mm, was disproportionately large when considered in the context of a fetus with a very small head, and, that bearing in mind the presence of the other factors, including the presence of a single umbilical artery, this amounted to further evidence that the fetus was at risk of suffering from microcephaly. Moreover, he pointed out that if the Vp/H ratio had been obtained, then it would have shown that it was on the 97.5^th centile, which was yet further evidence that the fetus was suffering from microcephaly.
163. Mr Howe disagreed with the views expressed by Mr Taylor in relation to this issue. He stated that given the accepted definition of ventriculomegaly, a ventricle atrial width of 9.5mm would not be considered to be abnormal, and that he didn't consider it appropriate to take into account the head circumference measurement. Moreover, although he acknowledged that the Vp/H ratio was available on the Astraia system, he stated that this calculation had not been the standard method of assessment for many years.
164. Mr Taylor agreed that none of the academic literature which had been produced for the purposes of the case, required the Vp/H ratio to be obtained for the purposes of diagnosing the presence of ventriculomegaly. However, he explained that the reason why the head circumference measurement was potentially relevant to the assessment of the significance of the atrial width in the present case, and indeed why the Vp/H ratio was available on the Astraia system, was because microcephaly involves the shrinkage of the brain, which is one of the causes of ventriculomegaly. Therefore, in the context of a small head, the ventricular measurements may have more significance than otherwise, as depending upon the measurement of the atrial width, they may indicate the presence of microcephaly. Indeed, it is of note that one of the structural abnormalities associated with microcephaly in the Lubusky et al study, was ventriculomegaly.
165. In his evidence, although Mr Howe did not consider it appropriate to take into account the head circumference measurement when seeking to assess the potential significance of an atrial width measurement, he did not explain why he considered it inappropriate. Moreover, beyond stating that the Vp/H ratio hadn't been the standard method of assessment for ventriculomegaly for many years, he did not suggest that the it wasn't potentially relevant to such an assessment. Nor indeed did he seek to disagree that one of the causes of ventriculomegaly is the presence of microcephaly, hence the known association between the two disorders.
166. I am afraid that I found Mr Howe's complete disavowal of the appropriateness of having any regard to the fetal head circumference when considering the ventricle width, to lack rational foundation, given what I accept, depending upon the particular measurements obtained, is its potential relevance to the consideration of whether a fetus is at risk of suffering from microcephaly. In contrast, I am satisfied that Mr Taylor is correct, and that, depending upon the measurements concerned, there is a sound logical basis for the relevance of taking into account the fetal head circumference measurement, when assessing the significance of the atrial width measurement.
167. I readily accept that in the vast majority of cases, where the fetus' head is well within the normal range, and the atrial width is no more than 10mm, Mr Howe is correct and this will not be required. However, where, as here, there is a head circumference significantly below the 3^rd centile, and an atrial width approaching the diagnostic criterion for ventriculomegaly, then in view of the nature of one of the potential causes of the condition, namely brain shrinkage, there appears to be sound logical reason for the necessity of having regard to the head circumference measurement. Indeed, in the absence of any alternative explanation, I can see no other reason for the Vp/H ratio being available on the Astraia system, and I note that not only was this ratio obtained by Andrew Zavos at the 3^rd scan, and Mr Sau at both the 4^th and 8^th scans, but in the report of the 8^th scan, Mr Sau specifically noted that there was a "normal VpH ratio."
168. It seems to me that the fact that the academic literature does not require the Vp/H ratio to be obtained, if in part it isn't explained by the nature of its target audience, neither undermines the logical basis for its potential significance, nor refutes its potential relevance where, as here, it is available on the electronic system being used to calculate the various fetal measurements. Moreover, the lack of a requirement to calculate the ratio in the vast majority of cases, does not in my view undermine its potential relevance in those cases where, as here, both the head circumference measurement is within the danger zone, and the atrial width measurement is close to the diagnostic border.
169. In these circumstances, I am satisfied that Mr Taylor is correct and that any reasonable clinician would, given the presence of a head circumference measurement significantly below the 3^rd centile, and an atrial width approaching the diagnostic criterion for ventriculomegaly, have recognised the potential significance of these two factors to each other. In this regard, there is nothing in the scan report to suggest that any such consideration was given to this issue by Miss Abdo-Nassri; merely reassurance that the posterior ventricle was only 9.5mm. Moreover, it is evident that Miss Abdo-Nassri did not obtain the Vp/H ratio which was available to her on the Astraia system. Something which, if she had ascertained it, would have informed her that the VpH ratio was on the 97^th centile, which would have been another significant factor for her to have taken into account when determining whether the fetus was at risk of suffering from microcephaly.
170. However, even if the possible presence of ventriculomegaly is put to one side, the situation faced by Miss Abdo-Nassri at the 7^th scan was that the fetal head circumference measurement was now even further below the 3^rd centile than it was at the 4^th scan. It is correct that it still did not reflect 3 standard deviations below the mean; albeit it was extremely close at 2.68. However, most significantly, when comparison is made with the previous scans, it represented a further slowing of growth velocity from the previous scan.
171. It is correct that if Miss Abdo-Nassri had taken into account the HC/AC ratio, she would have ascertained that it was high, at the 95^th centile, which might have indicated intrauterine growth restriction. However, although I am conscious that I have not heard from Miss Abdo-Nassri, not only is there no indication from the scan report that she took the HC/AC ratio into account, but there is no indication that she considered that intrauterine growth restriction was a possible explanation for the small fetal head circumference. Indeed, although on the previous scan the PI was high, Miss Abdo-Nassri noted that, contrary to intrauterine growth disorder being a possible explanation for the small head circumference, "Otherwise there was satisfactory growth velocity, liquor volume and umbilical artery doppler." This not only appears to suggest that she did not consider that the fetus was suffering from intrauterine growth restriction, (and the liquor volume and umbilical artery doppler would have supported her in that conclusion), but, most significantly, she appears to acknowledge that in contrast to the small head circumference, the other fetal measurements displayed satisfactory growth velocity.
172. Mr Howe acknowledges that there had been a further fall in the centile position of the head circumference measurement, but concludes that, because of the lack of a disproportionately small HC/AC ratio, there was insufficient evidence that the fetus was at risk of suffering from microcephaly. Indeed, it is pointed out on behalf of the defendant that the ratio was disproportionately high, and thus would have indicated the possible presence of intrauterine growth restriction. As I have pointed out, not only is there no indication that Miss Abdo-Nassri took into account the HC/AC ratio, but she appears to have concluded that the fetus was not suffering from intrauterine growth restriction. However, regardless of her conclusion on this point, as I explained in my earlier conclusions, although the HC/AC ratio may have relevance to the diagnosis of microcephaly, I do not consider that it has the determinative potential which Mr Howe's seeks to afford it.
173. Moreover, just as with the 5^th scan, and even more so when considering the further drop in centile position reflected by the head circumference measurement, I do not consider that Mr Howe's opinion sufficiently takes into account the significance of the loss in head growth velocity which is disclosed on the growth chart for the 7^th scan.
174. In these circumstances, I am satisfied that Mr Taylor is correct that there was now even more evidence available at the 7^th scan that there was at risk of suffering from microcephaly, which, on this occasion, required further investigation and assessment at tertiary level. In this regard, I do not consider that it is in any way a satisfactory answer, that Miss Abdo-Nassri was a tertiary level specialist. Indeed, in my judgment not only should she have appreciated the risk that the fetus was suffering from microcephaly, but, given her comment that, "We may consider Brain MRI post delivery.", it seems that she may have done so, yet failed to take the appropriate action of referring the claimant for further investigation and assessment at King's College Hospital. Indeed, the defendant has failed to provide any other explanation, reasonable or otherwise, for why Miss Abdo-Nassri considered that such a significant post-natal step might be considered to be appropriate.

Conclusion

175. I am conscious that, in reaching these conclusions, I have rejected various aspects of Mr Howe's opinions which have been relied upon by the defendant in order to establish that the actions of both Mr Sau and Miss Abdo-Nassri reflected reasonable clinical practice. I am also conscious of the high hurdle that is required to be surmounted by any claimant, in the face of such expert evidence, to satisfy the court, not that their own expert's evidence should be preferred, but that the opposing evidence and opinion does not reflect reasonable clinical practice. However, having considered the evidence relied upon by the defendant with considerable care, I am left in the position of being quite satisfied that in relation to a number of important and relevant issues, Mr Howe's conclusions were not only inconsistent with the fetal scan measurements and reports, but most importantly lacked a sufficiently logical and rational basis.
176. Moreover, that whilst seeking to explain individual issues disclosed by the scans upon the basis of their lack of diagnostic sufficiency, his overall opinion failed to take into account both the combination of relevant factors which were present in the case, and the context in which the issues were required to be considered, namely whether they disclosed sufficient evidence that the fetus was at risk of suffering from microcephaly, so as to require the claimant's referral for further investigation and assessment at a tertiary level centre.
177. In contrast, not only did I find Mr Taylor's opinions to be logically based, but I consider that his more nuanced approach, of taking into account the whole of the relevant evidence disclosed by the various scan measurements and reports, rather than compartmentalising it, reflected a more rational approach, and one ultimately which reflected reasonable, rather than inappropriately high, standards of clinical care.
178. In these circumstances, I am satisfied that the care provided by the defendant to the claimant at the 5^th and 7^th scans reflected inappropriately low standards of clinical care, and that the results of these scans provided sufficient evidence from which no reasonable clinician should have failed to appreciate that the fetus was at risk of suffering from microcephaly, so as to require, at the 5^th scan, either referral for further investigation and assessment at a tertiary level centre, or at least a re-scan at 32 weeks' gestation, and at the 7^th scan, referral for further investigation and assessment at a tertiary level centre.

List of medical acronyms used in the judgment

AC: abdominal circumference
BPD: biparietal diameter
DAU: day assessment unit
EDF: end diastolic flow
FL: femur length
FMU: fetal medicine unit
HC: head circumference
NT: nuchal translucency
PI: pulsivity index
UA: umbilical artery
Va: anterior cerebral ventricle diameter
Va/H: anterior cerebral ventricle hemisphere
Vp: posterior cerebral ventricle diameter
Vp/H: posterior cerebral ventricle hemisphere