Case of note: PP v. Cambridge University Hospitals NHS Foundation Trust (High Court, 17 May 2022 – Ritchie J.)

Date published:


The claimant suffered from cardiac problems and had refused therapeutic anti-coagulation over a period of years.  In September 2015, whilst at home, she experienced her right foot going very cold and turning white periodically.  She was taken to hospital.  The trust accepted that it had been negligent in failing to treat her with immediate injections of Heparin.  Sadly, PP had a severe stroke three days later and is now permanently disabled.  The issue before the court was whether appropriate treatment would have made any difference to the eventual outcome.


Four medical experts gave evidence on causation, two for each party.  On behalf of PP, a consultant neurologist opined that the only correct treatment would have been anti-coagulation by daily injections of Heparin for three days.  Had that occurred, his view on the balance of probabilities was that the subsequent stroke would have been prevented.  For the trust, a consultant in general medicine and strokes argued that owing to the relatively short time-scale involved, immediate anti-coagulation of the type suggested would not have prevented the stroke because there was a large blood clot occluding the left internal carotid artery.

A consultant haematologist for PP opined that treatment with Heparin and Warfarin simultaneously should have been commenced immediately.  He stated that Heparin has a rapid effect and was fully active within an hour of commencement.  Its major action was to prevent further clot formation.  On the balance of probabilities, that would have prevented the stroke.

The defendants called a consultant haematologist practising at a major thrombosis unit.  He advised that there was little evidence from published papers that Heparin was effective in the prevention of arterial thromboembolism in patients with atrial fibrillation (from which PP had suffered since at least 1997).  He considered that the stroke was probably caused by embolism of the thrombus in the left atrium of the heart due to atrial fibrillation.  There was some evidence for a reduction of the risk beginning three to four weeks after therapeutic levels of anti-coagulation had been achieved, and that such levels were generally achieved on Warfarin within one to two weeks.  However, that would not have been soon enough to prevent the stroke.

In view of these sharp differences of expert opinion, the judge considered academic literature in detail.  Many papers were cited by the experts to back their respective views.  The lack of trial studies was notable, but this was because carrying out such studies where half the patients would have been in acute danger of death or suffering a serious stroke would not have been ethical.

On balance, Mr. Justice Ritchie considered that the views of the claimant’s haematologist were “more logical and better reasoned” than those of the trust’s expert.  Consequently, he gave judgment for PP, holding that on the balance of probabilities Heparin would have prevented the formation of new clots and also prevented propagation of the mother clot, which in turn would have stopped the mother clot embolising and causing the stroke.


This was a case where distinguished experts held radically differing views.  The judge had to consider the performance of each under cross-examination by experienced counsel and also the extensive academic literature, which lacked directly relevant clinical studies for ethical reasons.  Choosing between contrasting opinions is something judges have to do frequently, and it can be difficult to predict the outcome.  The trust’s haematology expert was (and indeed is) a leading figure in the field of thrombolysis, having written many relevant papers himself and being a lecturer on the subject.  This was undoubtedly an extremely sad case for PP and her family, but the trust’s defence was supported by one of the foremost specialists in the country.  We are now proceeding to quantify the claim and to try and agree damages as soon as feasible.