Pickering v Cambridge University Hospitals NHS Foundation Trust [2022] EWHC 1171 (QB)

In this post, Thea Wilson considers this recent stroke case which involves issues of causation.

The Facts

The Claimant, a 52-year-old woman, had suffered from muscular dystrophy and atrial fibrillation for a number of years. From the mid-2000s onwards, she had been repeatedly recommended to start anti-coagulation, but had been reluctant to do so, taking Aspirin instead. A pacemaker was inserted in 2007.

On 24 September 2015, the Claimant started suffering from symptoms of pins and needles, cold and whiteness in her right leg. An ambulance was called and she was taken to A&E, arriving at 22:04. She was triaged and sent to an out of hours GP. The GP saw her at 22:23 and referred her back to the emergency department for further work-up. She was seen again at 01:35 on 25 September 2015 and discharged with a suspected resolved ischaemic event in the right leg. The Claimant was advised to restart aspirin, but was not given any other medications.

In the evening of 27 September 2015, the Claimant suffered a massive stroke at home. A blood clot or clots had travelled from her heart to her brain. The earlier DVT was also caused by a clot travelling from her heart into her right leg. The clots caused initial damage which worsened over the next two days despite prompt treatment with thrombolytic drugs.

The case was heard over four days in early May 2022. At the end of the first day of trial, the Defendant admitted that it had been negligent in failing to treat the Claimant with an immediate low molecular weight heparin injection shortly before 02:00 on 25 September 2015. Causation remained in issue, however: specifically whether, but for the Defendant’s negligence in failing to start Heparin treatment just before 02:00 on 25 September 2015, the Claimant would have avoided suffering a stroke 67 hours later.

The parties called evidence from experts in A&E medicine (Dr Jaffey for the Claimant and Mr Saab for the Defendant), Neurology (Dr Michael for the Claimant), General medicine, Geriatrics and Strokes (Dr Giallombardo for the Defendant), and Haematology (Professor Mehta for the Claimant and Dr Patel for the Defendant).

The crucial evidence came from the Haematologists. They agreed that therapeutic oral anti-coagulation would have reduced the Claimant’s risk of stroke by around 66% over three to four weeks, but disagreed on the likely effects of such treatment over a period of 67 hours. Both relied on various studies, none of which had looked at this particular emergency situation.

The Claimant’s expert considered that the lack of studies in acute situations was not because Heparin lacked effect in these but due to the acute emergency. He considered that Heparin was recommended in these situations for a reason. He advised that Heparin commences action within minutes of administration and made an analogy with studies of DVT where the risk of pulmonary embolism has been found to reduce within 24-36 hours of administration.

The Defendant’s expert considered that the evidence for effectiveness of Heparin in these situations was lacking. The fact that it was recommended for use in these acute situations and that physicians believed it would help did not prove Heparin’s effectiveness. He accepted that Heparin was effective in preventing emboli from DVT and pulmonary embolism, but considered that this did not translate. He also considered that even if Heparin shrunk the main clot, it did not reduce the risk of other clots breaking off and travelling round the body.

The Judgment

Ritchie J handed down his judgment on 17 May 2022. After a thorough analysis of the expert evidence and the medical literature upon which it was based, Ritchie J concluded that he preferred the evidence of the Claimant’s Haematologist as the more logical and better reasoned.

The key issue was whether administering Heparin 67 hours before the stroke would have prevented the stroke. Ritchie J found that had the Claimant been given Heparin, over the next 67 hours the clot would have reduced in size considerably and probably by over 50%. During this time, the structure of the thrombus would have been becoming more organised, less friable, more stable and more attached to the atrial wall. No new clots would have formed on the surface of the main clot, an embolus would have been prevented and the stroke on 27 September 2015 would also have been prevented.

If the stroke had been prevented, the effect of the anti-thrombotic treatment would have been that the Claimant would be left with a 66% chance of being stroke-free for the rest of her life. Accordingly, judgment was entered for the Claimant.


The case is an example of the need to test your own experts well prior to the hearing and, in particular, where it is in issue, to check that all their literature is available for review and that their reasoning on the basis of the literature can be supported:

  • Although the Defendant’s A&E consultant maintained his position on there not being a breach of duty in his oral evidence, he was unable to explain gaps in his medicolegal report and came close to indicating the Court that he had changed his view on breach under cross examination. Immediately after his evidence, the Defendant conceded breach of duty. Ritchie J observed that they were right to do so and that he would have rejected the Defendant’s expert’s evidence and found breach of duty.
  • It transpired that the Claimant’s neurologist had misquoted an article upon which he relied in the joint statements. He then attempted to rely on a paper he could not remember the name of and which he had failed to provide a copy of to either the Court or the Defendant’s expert.
  • Whilst there were criticisms of both haematologists’ styles of giving evidence to some extent, the Defendant’s expert was the subject of most criticism: he was found to “be rigid and then to produce rather extreme opinions”, making assertions about the reliability of studies that went too far and had to be withdrawn. Not all his claims on the basis of the literature stood up to logical scrutiny. Ritchie J noted that he was struck by Dr Patel’s reliance on certain papers to prove something that Ritchie J considered they just did not prove.

For more on managing experts and tips to ensure that you make the most of experts, see our webinar on the subject by Daniel Sokol and Thea Wilson, available through 12 King’s Bench Walk’s website.

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