Minor Head Injury and Anticoagulants

Minor Head Injury and Anticoagulants -You Snooze, You Ooze

We’re lucky to have NICE guidelines in the UK.  A couple of years ago, on a visit to the US, one of my collaborators from the US mentioned how jealous he was that we have them.  His practice was to get a CT scan for everyone with a head injury.  The NICE guidelines give us a framework for implementing evidence-based decision rules like the Canadian CT head and CHALICE rules​1​ on a widespread basis.  One area I think the NICE guideline for head injury can improve, however, is for anticoagulated patients with minor head injury.

The current NICE guideline suggests that we scan head-injured anticoagulated patients who have lost consciousness or have amnesia.  In the absence of other high risk features, however, the remainder of patients are potentially eligible for immediate discharge without even so much as an INR check.  This worries me.

Unfortunately, the Canadian CT head rule can’t really help us out here because that study excluded patients with coagulopathy.  The New Orleans rule didn’t exclude coagulopathic patients but their analysis was, shall we say, somewhat underpowered.  Although the incidence of bleeding was 0%, the total number of patients with coagulopathy in that study came to a grand total of 1!  So what is the evidence behind managing head injury in anticoagulated patients?

Fortunately, we do have some evidence, although it’s relatively limited if we’re honest. A case series of 144 patients​2​ demonstrated that the incidence of clinically important intracranial injury in warfarinised patients was 7%.  For me, that’s more than a sufficient risk to prevent me from ruling out a bleed in this group and to make me want to request a CT brain.  Roughly 7% of patients with chest pain who have a normal ECG are having an acute myocardial infarction.  But I wouldn’t dream of ruling out AMI just because the ECG is normal.  So neither should we consider ruling out intracranial haemorrhage at that level of risk.

What’s more, anticoagulated patients who develop an intracranial haemorrhage may not meet the NICE criteria for CT (which are based on the Canadian CT head rule, incidentally).  This means that they can bleed despite being relatively asymptomatic.  And a subtherapeutic INR doesn’t mean we can relax either, as shown in this great study from John Batchelor and Simon Rendell​3​ from my own institution.

OK, so we’re going to get a CT for these patients.  I’ve sold you that, right?  But if the CT’s normal, surely we can relax.  Right?

This great small study from Annals of Emergency Medicine​4​ sheds some light on that situation.  The authors implemented a protocol to immediately CT all warfarinised head injured patients, observe them for 24 hours, then re-scan them.  Of 97 patients, 87 agreed to stay in for observation and have a repeat scan.  5 (6%) of those patients had a late bleed, not detected on the initial scan.  OK, it was minimal in 2 patients.  But 1 required craniotomy.  What’s more, only 1 of those 5 patients had shown signs of neurological deterioration in the 24 hour period between scans.  2 further patients developed late bleeds even after a normal scan at 24 hours.   So, this study definitely tells us that there’s an important incidence of late bleeding in anticoagulated patients.  Not only do we need to strongly consider scanning these patients, but we also need to consider repeating the scan 24 hours later, even in the absence of neurological deterioration.  What’s more, the symptoms reported by the patient may not be a great predictor of intracranial bleeding.  Only 1 of the 6 who bled reported a severe headache, and only 1 was vomiting.  If we rely on our patient becoming symptomatic during the period of observation, we may still miss some late bleeds.

Of course, this is just one study.  Other studies​5​do confirm that there’s an incidence of late bleeding in anticoagulated patients, although it may not be quite as high as 6%.  However, what’s clear is that these patients ooze, and they ooze slowly.  Of course, we don’t want to miss a bleed, if present, initially.  Given the prevalence of bleeding at the time of presentation, I suggest that we should still scan these patients at presentation.  But we should also be alert to the possibility of late bleeds.

From discussions on Twitter, I know that some people are repeating the CT after 6 hours rather than 24.  There’s no evidence to definitively tell us which strategy is better.  In my practice, I’ll be strongly considering an initial scan, an INR check, a period of observation and a repeat scan after 24 hours for anticoagulated patients with a significant head injury.  It’s not clear whether that’s the optimal strategy.  What is clear is that we must be extremely careful with these patients.  They bleed.  And they bleed late.

So, what about reversal of the anticoagulation?  Well, that’s a whole different debate – you’ll have to watch this space for now!…


  1. 1.
    Dunning J, Daly JP, Lomas JP, et al. Derivation of the children’s head injury algorithm for the prediction of important clinical events decision rule for head injury in children. Archives of Disease in Childhood. Published online November 1, 2006:885-891. doi:10.1136/adc.2005.083980
  2. 2.
    Li J, Brown J, Levine M. Mild head injury, anticoagulants, and risk of intracranial injury. The Lancet. Published online March 2001:771-772. doi:10.1016/s0140-6736(00)04163-5
  3. 3.
    Rendell S, Batchelor JS. An analysis of predictive markers for intracranial haemorrhage in warfarinised head injury patients. Emerg Med J. Published online February 22, 2012:28-31. doi:10.1136/emermed-2011-200176
  4. 4.
    Menditto VG, Lucci M, Polonara S, Pomponio G, Gabrielli A. Management of Minor Head Injury in Patients Receiving Oral Anticoagulant Therapy: A Prospective Study of a 24-Hour Observation Protocol. Annals of Emergency Medicine. Published online June 2012:451-455. doi:10.1016/j.annemergmed.2011.12.003
  5. 5.
    BET 1. Emergency Medicine Journal. Published online October 23, 2010:873-874. doi:10.1136/emj.2010.104869

Cite this article as: Rick Body, "Minor Head Injury and Anticoagulants -You Snooze, You Ooze," in St.Emlyn's, August 3, 2012, https://www.stemlynsblog.org/you-snooze-you-ooze-anticoagulants-and-minor-head-injury/.

7 thoughts on “Minor Head Injury and Anticoagulants -You Snooze, You Ooze”

  1. I did an observational piece on this back in 1995 for “Medicine” now defunct. It was a case series of patients who presented to one ED. the delay to presentation was up to 6 weeks with Chronic SDH forming then, the mix of bleeds was ASDH, ICH and ventricular bleeds. Presumably the CSDH were small ASDH that absorbed water as they broke down and became symptomatic. The next question I ask is having found a small ICH what next? the normal response when I ring Neurosurgery (I used to be one) is: they are too well for intervention. When they go off, they are too ill!
    Also what do you do with the elderly intracerebral haemorrhage with minimal symptoms now. They almost all go bad over the next few weeks and there is nothing to do! So many questions, so few answers

  2. In my mind it is about the understanding of risk. Indeed, you parallel similar risks with chest pain, but these presentations are treated wholly differently. National guidelines and the mantra that minutes mean myocardium spur us on to act fast with chest pain and admit countless patients for 12-hour high-sensitivity troponins, whilst warfarinised head injuries languish and ooze. 

    Our study highlights the lack of commonality with which these patients are investigated and managed, borne out in the literature also. Several studies tell us of rapid pathways in Emergency Departments where coagulation is assessed on the way to a CT scan from triage so that reversal of anticoagulation can be instigated on the discovery of intracranial haemorrhage. Complete reversal of anticoaguation is achieved within 10 minutes of administration of PCC. There are national guidelines on reversal, but time to administration is of the essence. 

    Too often these bleeds are not amenable to neurosurgical intervention and, therefore, the mainstay of treatment is this rapid reversal to minimise morbidity and mortality. Arguably the best results would then be in the asymptomatic patient. 

    These patients need urgent assessment and investigation with appreciation of how we can shorten each step in the process. This is the focus of my MSc dissertation for our institution, as it is my belief that minutes mean morbidity. 

  3. Great article as ever Rick.

    How minimal or minor would a head injury have to be not to CT though?

    If the patient was completely a symptomatic, had no high risk features and had relatively minor trauma, would you still CT.

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