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Anticoagulated patients and head injury | Signal

Reference number
Issue date29 October 2010

This Signal concerns the risk of missing intra-cerebral injury in anticoagulated patients who suffer head injuries.

A sample incident reads:

....brought in by ambulance after fall with facial injury. No loss of consciousness or amnesia but complained of severe headache. On Warfarin - Registrar requested urgent CT scan 22.00 but Radiologist said does not meet criteria. Admitted for observation, deteriorated at 01.30 and subsequently INR found to be >8. large acute intracerebral haemorrhage

Anticoagulated patients are more vulnerable to intracerebral bleeding after head injury, and more likely to die if an intra-cerebral bleed occurs. This is reflected by the specific advice for CT scanning after head injury in anticoagulated patients offered by NICE and SIGN guidance. Clinical guidance has to balance the risk of missing intracerebral injury with the risk that too low a threshold for CT scanning would disadvantage other patients.

Following a trigger incident, a search of the National Reporting and Learning System (NRLS) identified six cases where an anticoagulated patient died or became critically ill after a delay in diagnosing an intracerebral injury. Thresholds for CT scanning appeared to be a factor in the delay. Further information from the trusts reporting these incidents identified:

• the patients had not reported amnesia or loss of consciousness, or any other criteria for urgent CT scanning (e.g. dangerous mechanism of injury);

• two of the six patients were over their target threshold for anticoagulation, but this was not detected until some hours later;

• confusion between a unit's written protocol reflecting NICE guidance, and an unwritten expectation that medical staff should have a lower threshold for urgent CT.


A survey by the College of Emergency Medicine found that many (but not all) local policies believed that CT scanning should be carried out more often than required by NICE guidance e.g. “all on warfarin get a CT scan”; “we scan all but the most trivial injury”.

Emergency departments should review and amend policies and protocols to highlight the increased risk of bleeding, the importance of early CT scanning and the need for early INR (International Normalised Ratio) testing in anticoagulated patients following head injury.

Please contact us with information about your initiatives to reduce risks in any of these areas.

Signals are notifications of key risks emerging from review of serious incidents reported to the NRLS and shared by the NPSA.