Hilary Term [2015] UKSC 11 On appeal from: [2013] CSIH 3; [2010] CSIH 104 JUDGMENT Montgomery (Appellant) v Lanarkshire Health Board (Respondent) (Scotland) before Lord Neuberger, President Lady Hale, Deputy President Lord Kerr Lord Clarke Lord Wilson Lord Reed Lord Hodge JUDGMENT GIVEN ON 11 March 2015 Heard on 22 and 23 July 2014 Appellant Respondent James Badenoch QC Rory Anderson QC Colin J MacAulay QC Neil R Mackenzie Lauren Sutherland (Instructed by (Instructed by NHS Balfour+Manson LLP) National Services Scotland Central Legal Office) Intervener (General Medical Council) Andrew Smith QC (Instructed by GMC Legal) LORD KERR AND LORD REED: (with whom Lord Neuberger, Lord Clarke, Lord Wilson and Lord Hodge agree) Introduction 1. Nadine Montgomery gave birth to a baby boy on 1 October 1999 at Bellshill Maternity Hospital, Lanarkshire. As a result of complications during the delivery, the baby was born with severe disabilities. In these proceedings Mrs Montgomery seeks damages on behalf of her son for the injuries which he sustained. She attributes those injuries to negligence on the part of Dr Dina McLellan, a consultant obstetrician and gynaecologist employed by Lanarkshire Health Board, who was responsible for Mrs Montgomery’s care during her pregnancy and labour. She also delivered the baby. 2. Before the Court of Session, two distinct grounds of negligence were advanced on behalf of Mrs Montgomery. The first concerned her ante-natal care. It was contended that she ought to have been given advice about the risk of shoulder dystocia (the inability of the baby’s shoulders to pass through the pelvis) which would be involved in vaginal birth, and of the alternative possibility of delivery by elective caesarean section. The second branch of the case concerned the management of labour. It was contended that Dr McLellan had negligently failed to perform a caesarean section in response to abnormalities indicated by cardiotocograph (“CTG”) traces. 3. The Lord Ordinary, Lord Bannatyne, rejected both grounds of fault: [2010] CSOH 104. In relation to the first ground, he based his decision primarily on expert evidence of medical practice, following the approach laid down by the majority in Sidaway v Board of Governors of the Bethlem Royal Hospital and the Maudsley Hospital [1985] AC 871. He also concluded that, even if Mrs Montgomery had been given advice about the risk of serious harm to her baby as a consequence of shoulder dystocia, it would have made no difference in any event, since she would not have elected to have her baby delivered by caesarean section. That decision was upheld by the Inner House (Lord Eassie, Lord Hardie and Lord Emslie): [2013] CSIH 3; 2013 SC 245. 4. The appeal to this court has focused on the first ground of fault. The court has been invited to depart from the decision of the House of Lords in Sidaway and to re-consider the duty of a doctor towards a patient in relation to advice about treatment. The court has also been invited to reverse the findings of the Lord Ordinary in relation to causation, either on the basis that his treatment Page 2 of the evidence was plainly wrong, or on the basis that, instead of applying a conventional test of “but for” causation, he should instead have applied the approach adopted in the case of Chester v Afshar [2004] UKHL 41; [2005] 1 AC 134. 5. Before considering those issues, we shall explain in greater detail the relevant facts and the approach adopted by the courts below. The facts 6. Mrs Montgomery studied molecular biology at Glasgow University and graduated with a BSc. She then worked for a pharmaceutical company as a hospital specialist. She was described by the Lord Ordinary as “a clearly highly intelligent person”. Her mother and sister are both general medical practitioners. 7. In 1999 Mrs Montgomery was expecting her first baby. She is of small stature, being just over five feet in height. She suffers from insulin dependent diabetes mellitus. Women suffering from diabetes are likely to have babies that are larger than normal, and there can be a particular concentration of weight on the babies’ shoulders. Because of her diabetes, Mrs Montgomery’s was regarded as a high risk pregnancy requiring intensive monitoring. She therefore attended the combined obstetric and diabetic clinic at Bellshill Maternity Hospital, under the care of Dr McLellan, throughout her pregnancy. 8. The widest part of a baby’s body is usually the head. If the head successfully descends through the birth canal, in a normal birth the rest of the body will descend uneventfully. Since the widest part of the body of a baby whose mother is diabetic may be the shoulders the head may descend but the shoulders can be too wide to pass through the mother’s pelvis without medical intervention. This phenomenon, known as shoulder dystocia, is the prime concern in diabetic pregnancies which proceed to labour. It was described by Dr Philip Owen, an expert witness who gave evidence on behalf of the Board, as “a major obstetric emergency associated with a short and long term neonatal and maternal morbidity [and] an associated neonatal mortality”. 9. That evidence is consistent with guidance issued by the Royal College of Obstetricians and Gynaecologists, which states that there can be a high perinatal mortality and morbidity associated with the condition, even when it Page 3 is managed appropriately. Maternal morbidity is also increased: in 11% of cases of shoulder dystocia there is postpartum haemorrhage, and in 3.8% fourth degree perineal tears. The guidance advises that help should be summoned immediately when shoulder dystocia occurs. When the mother is in hospital this should include assistance from midwives, an obstetrician, a paediatric resuscitation team and an anaesthetist. 10. According to the evidence in this case, about 70% of cases of shoulder dystocia can be resolved by what is known as a “McRoberts’” manoeuvre. This involves two midwives or nurses taking hold of the mother’s legs and forcing her knees up towards her shoulders, so as to widen the pelvic inlet by means of hyperflexion. An attempt can also be made to manoeuvre the baby by suprapubic pressure. This procedure involves the doctor making a fist with both hands and applying pressure above the mother’s pubis, in order to dislodge the baby’s shoulder and push the baby down into the pelvis. Another procedure which may be attempted is a “Zavanelli” manoeuvre. This involves pushing the baby’s head back into the birth canal, to the uterus, so as to be able to perform an emergency caesarean section. Another possible procedure is a symphysiotomy. This is a surgical procedure which involves cutting through the pubic symphysis (the joint uniting the pubic bones), so as to allow the two halves of the pelvis to be separated. 11. According to Dr McLellan’s evidence, in some cases the mother may be entirely unaware that shoulder dystocia has occurred. It is clear, however, that when shoulder dystocia happens and the mother knows of it, dealing with it is, at least, an unpleasant and frightening experience for her. It also gives rise to a variety of risks to her health. 12. Shoulder dystocia also presents risks to the baby. The physical manoeuvres and manipulations required to free the baby can cause it to suffer a broken shoulder or an avulsion of the brachial plexus – the nerve roots which connect the baby’s arm to the spinal cord. An injury of the latter type may be transient or it may, as in the present case, result in permanent disability, leaving the child with a useless arm. The risk of a brachial plexus injury, in cases of shoulder dystocia involving diabetic mothers, is about 0.2%. In a very small percentage of cases of shoulder dystocia, the umbilical cord becomes trapped against the mother’s pelvis. If, in consequence, the cord becomes occluded, this can cause the baby to suffer from prolonged hypoxia, resulting in cerebral palsy or death. The risk of this happening is less than 0.1%. 13. Mrs Montgomery was told that she was having a larger than usual baby. But she was not told about the risks of her experiencing mechanical problems during labour. In particular she was not told about the risk of shoulder Page 4 dystocia. It is agreed that that risk was 9-10% in the case of diabetic mothers. Unsurprisingly, Dr McLellan accepted that this was a high risk. But, despite the risk, she said that her practice was not to spend a lot of time, or indeed any time at all, discussing potential risks of shoulder dystocia. She explained that this was because, in her estimation, the risk of a grave problem for the baby resulting from shoulder dystocia was very small. She considered, therefore, that if the condition was mentioned, “most women will actually say, ‘I’d rather have a caesarean section’”. She went on to say that “if you were to mention shoulder dystocia to every [diabetic] patient, if you were to mention to any mother who faces labour that there is a very small risk of the baby dying in labour, then everyone would ask for a caesarean section, and it’s not in the maternal interests for women to have caesarean sections”. 14. During her fortnightly attendances at the clinic, Mrs Montgomery underwent ultrasound examinations to assess foetal size and growth. The final ultrasound examination was on 15 September 1999, at 36 weeks gestation. Dr McLellan decided that Mrs Montgomery should not have a further ultrasound examination at 38 weeks, because she felt that Mrs Montgomery was becoming anxious as a result of the information revealed by the scans about the size of her baby.