§ GUIDE · ANTICOAGULANT ERRORS

The blood thinner was missed, stopped,
or given at the wrong moment.

Anticoagulants are a two-sided drug. Miss a dose or fail to start them and a clot can travel to the lungs or the brain. Give them too early after surgery and a bleed can press on the spinal cord. These six judgments show both kinds of failure, and what the courts asked before making anyone pay.

Judgments read

6

Claimant succeeded

5 of 6 (1 in part)

Pickering: stroke after

67 hours

Lesforis: Clexane given

Within 3 hours

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§ BEFORE YOU GO FURTHER

For an anticoagulant claim to get anywhere, these things usually need to be true

  • There was a known clot risk (atrial fibrillation, a past DVT or PE, surgery) and anticoagulation was not started, a dose was missed, or it was stopped with no plan to restart.
  • Or an anticoagulant was given at a time or dose that carried a recognised bleeding risk, and a bleed or haematoma followed.
  • A stroke, clot, embolism or bleed happened after that decision, and expert evidence can say the right treatment would probably have prevented it.
  • It happened within the last three years, or you only recently learned that care fell short. For a death, three years from the death.

Critchlow is the caution. The trust admitted it should have investigated, but the court found there was no clot to find that day and the later dose reduction was reasonable. An admitted mistake with nothing behind it does not pay.

§ 01

Not started: the clot that was allowed to travel.

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

A woman with atrial fibrillation attended A&E with a cold, white leg. Doctors diagnosed a resolved ischaemic event and sent her home on aspirin, without heparin and without a warning about her stroke risk. She had a massive stroke 67 hours later. Breach was admitted on the first day of trial, and the judge accepted that heparin would have stopped the clot in her heart from growing.

Dakin v South Tees Hospitals [2026] EWCC 26

A theatre nurse with worsening palpitations saw a hospital physician who admittedly failed to arrange 24-hour heart monitoring. The judge found monitoring would have caught her atrial fibrillation in time for anticoagulants to prevent the stroke she went on to suffer, and gave judgment with damages to be assessed.

Marshall v Schembri [2019] EWHC 283 (QB)

A woman with a previous pulmonary embolism saw her GP with chest pain and breathlessness and was diagnosed with a strained muscle. She died the next morning. The GP admitted he should have referred her to hospital, and the court found she would have survived with anticoagulation and monitoring.

§ 02

Omitted: the injection that was never given.

Tuffin v University Hospitals Coventry and Warwickshire [2024] EWHC 3318 (KB) is the clearest example of a missed dose, and of how carefully the courts measure what it caused. After spinal surgery the hospital failed to give Ms Tuffin the anti-clotting injection that had been prescribed. She developed a deep vein thrombosis and post-thrombotic syndrome. Three years later her leg was amputated above the knee.

The judge held the trust liable for the DVT and its after-effects, but found the amputation was caused by complex regional pain syndrome arising from the surgery itself, not by the clot. The missed injection was negligent; compensation covered only the harm the clot actually did.

§ 03

Given too soon: the bleed after spinal surgery.

The other side of the drug is Lesforis v Tolias [2018] EWHC 1225 (QB). Two days after spinal fusion surgery at a private clinic, Mrs Lesforis suddenly lost movement in her feet. A second operation found a blood clot pressing on the spinal cord. Martin Spencer J held that it was negligent to give the blood thinner Clexane routinely within about three hours of spinal surgery, that this caused the haematoma, and that the surgeon's habit of always doing so did not make it acceptable.

The point generalises. Anticoagulation after surgery is a balance between clot risk and bleeding risk that has to be struck for each patient, and a routine that falls outside the normal range at the time can be negligent even if it never went wrong before.

§ 04

Admitted failure, no clot: why Critchlow failed.

Critchlow v University Hospitals of North Midlands [2022] EWHC 949 (QB) shows the limit. A former lorry driver with a history of pulmonary embolism attended A&E and clinics in 2015 with chest pain and calf symptoms. The trust admitted it should have calculated his clot risk score and arranged imaging at the first visit. The judge nonetheless found he did not have a clot on that date, pointing to his normal D-dimer blood results, and that a later reduction in his apixaban dose was not negligent. The claim was dismissed.

An admitted failure to investigate only leads to compensation if the investigation would have found something. That is why the blood results and scans from the time matter as much as the admission.

§ 05

What the records should show.

  • The clot-risk assessment on admission, which national guidance requires for every adult admitted to hospital.
  • The drug chart: what was prescribed and, separately, what was actually given and when. Tuffin turned on the gap between the two.
  • The discharge letter: whether anticoagulation was to continue or restart, and who was told.
  • The GP record of any decision to stop or reduce the drug, and the reason given.
  • Monitoring results for warfarin, and the ECG or heart monitor report where a rhythm problem was suspected.
  • Scan results and D-dimer tests, which were decisive in Critchlow.

§ THE JUDGMENTS BEHIND THIS GUIDE

The six judgments behind this guide.

Four claimants succeeded outright, one succeeded in part, and one failed. The partial win and the loss show how precisely causation is tested.

Claimant succeeded

Phoebe Charmaine Pickering v Cambridge University Hospitals NHS Foundation Trust

[2022] EWHC 1171 (QB)·2022·Liability decided at trial

Ms Pickering, who had atrial fibrillation, attended A&E with a cold, white leg; doctors diagnosed a resolved ischaemic event and sent her home on aspirin without heparin or a warning about her stroke risk. She had a major stroke 67 hours later, and the court found that anticoagulation would have prevented it.

A transient blockage in a limb can signal a clot from the heart, and discharging such a patient without anticoagulation or advice was admitted to be negligent. The case turned on causation, with the court accepting expert evidence that heparin would have stopped the clot progressing.

Claimant succeeded

Dakin v South Tees Hospitals NHS Foundation Trust

[2026] EWCC 26·2026·Liability decided at trial

A theatre nurse with worsening palpitations saw a hospital physician who admittedly failed to arrange 24-hour ECG monitoring. The judge found monitoring would have caught her atrial fibrillation in time for anticoagulants to prevent the stroke she suffered.

Palpitations that keep coming back need proper heart-rhythm monitoring. Where a missed test would have led to blood-thinning treatment, a later stroke can be laid at the hospital's door.

Claimant succeeded

Marshall v Schembri

[2019] EWHC 283 (QB)·2019·Liability decided at trial

A woman with a previous pulmonary embolism saw her GP with chest pain and breathlessness and was diagnosed with a strained muscle; she died the next morning. The GP admitted he should have referred her to hospital, and Stewart J found she would on the clear balance of probabilities have survived with anticoagulation and monitoring.

Chest pain and breathlessness in someone with a past clot is a red flag needing same-day hospital referral. Where survival chances on admission would have been very high, the court will find the death was caused by the failure to refer.

Mixed outcome

Jessica Tuffin v University Hospitals Coventry and Warwickshire NHS Trust

[2024] EWHC 3318 (KB)·2024·Liability decided at trial

After spinal surgery the hospital failed to give Ms Tuffin the prescribed anti-clotting injection, and she developed a deep vein thrombosis and post-thrombotic syndrome; three years later her leg was amputated above the knee. The judge held the trust liable for the DVT and its after-effects but found the amputation was caused by complex regional pain syndrome from the surgery itself, not the clot.

A missed dose of thromboprophylaxis that causes a DVT is negligent, but compensation covers only the harm the clot actually caused. Where a separate condition drives the worst outcome, the claimant must show the negligence at least materially contributed to it.

Claimant succeeded

Lesforis v Tolias

[2018] EWHC 1225 (QB)·2018·Liability decided at trial

Two days after spinal fusion surgery Mrs Lesforis suddenly lost movement in her feet; re-operation found a compressive blood clot. Martin Spencer J held it was negligent to give the blood-thinner Clexane routinely within about three hours of spinal surgery, which caused the haematoma, although the timing of the re-operation was not negligent.

Routine practices that fall outside the normal range at the time can be negligent even if the surgeon always did it that way. Post-operative anticoagulation after spinal surgery carries a recognised bleeding risk that must be weighed for each patient.

Claim failed

Critchlow v University Hospitals of North Midlands NHS Trust

[2022] EWHC 949 (QB)·2022·Liability decided at trial

A former lorry driver with a history of pulmonary embolism attended A&E and clinics in 2015 with chest pain and calf symptoms; the Trust admitted it should have done a Wells score and imaging at the first visit. The judge found he did not actually have a clot on that date and that the later reduction of his apixaban was not negligent, so the claim failed.

An admitted failure to investigate only leads to compensation if the investigation would have found something. Normal D-dimer results were decisive evidence against a missed clot.

Browse the whole case library →

Contains information licensed under the Open Justice - Licence v2.0. Judgments from Find Case Law, The National Archives. Summaries are ours; amounts only where printed in the judgment.

§ QUESTIONS

Common questions

My relative's blood thinner was stopped before a procedure and never restarted, and they died of a pulmonary embolism. Is that a claim?

Possibly. The questions are whether there was a plan to restart, whose job it was, and whether restarting would probably have prevented the embolism. Marshall v Schembri shows a court finding that anticoagulation would have saved a patient with a previous clot.

The hospital did not give me my blood thinner injections after surgery and I developed a DVT. Can I claim?

Yes, if the injections were prescribed or indicated and not given. In Tuffin v University Hospitals Coventry and Warwickshire the trust was liable for the DVT and post-thrombotic syndrome that followed a missed dose, though not for a later amputation that had a different cause.

The blood thinner caused a bleed. Can that be negligence?

Bleeding is a recognised risk, so the question is whether the drug was given at a time or dose that a competent clinician would have avoided. In Lesforis v Tolias giving Clexane within about three hours of spinal surgery was held negligent because of the known risk of a spinal haematoma.

An irregular heartbeat was found but not treated, and then I had a stroke.

Pickering and Dakin are both that pattern. In each the court found that anticoagulation, or the monitoring that would have led to it, would have prevented the stroke. The expert evidence on timing is what makes or breaks these claims.

A&E has admitted it should have scanned me. Do I automatically win?

No. In Critchlow the trust admitted it should have investigated and the claim still failed, because the judge found there was no clot to find on that date. An admission of breach is only half of the claim.

How long do I have?

Three years from the stroke, clot or bleed, or from when you first knew that care had fallen short. For a death, three years from the date of death or of knowledge.

§ MORE GUIDES

Plain answers to the other questions people ask.

Why claims fail →

Eleven real judgments where the claim failed, and what each one teaches about proving breach of duty, causation and loss in a medical negligence claim.

Stroke claims →

Seven published judgments where a stroke, mini-stroke or its cause was missed or not treated. Five failed. What separated the two that succeeded.

Medication errors →

Five published judgments on drugs given wrongly, too soon, or not at all: anticoagulants, vitamins, antibiotics and preventive drugs. Three succeeded.

Blood clot claims →

Eight published judgments on pulmonary embolism, DVT, stroke-causing clots and blood thinners not given. Four succeeded. What separated them.

Died after being sent home →

A discharge from A&E, a GP visit or a paramedic's decision that ended in a death: what four families proved, why three claims failed, how fatal claims are built.

NHS payout data →

Official NHS Resolution figures, band by band, for 2024/25.

This guide is general information about the law in England and Wales, not legal advice about your case. ClaimGavel is run by Costart Projects Ltd on behalf of Tomlin & Partners, a specialist medical negligence firm regulated by the SRA. The free assessment on this page is an AI overview to show you roughly where you stand; a solicitor confirms the position in a free, no-obligation conversation.