Head injury and anticoagulation


A 79 year old gentleman attends the Emergency Department (ED) after having tripped over his dog whilst out walking. He sustained a laceration to the back of his head. He did not lose consciousness, he has not vomited, has no amnesia, GCS 15 throughout and there was no evidence of a depressed or basal skull fracture. There had been no seizures reported and examination revealed no focal neurology. Additional social history revealed that he currently lives at home with his son and daughter-in-law.

He had a CT head in the ED as he takes anticoagulants, which showed no evidence of Intra-Cranial Haemorrhage (ICH).

So what?

The risk of developing an ICH following a head injury is 42.2 times higher in warfarinised patients than patients not on anticoagulants (Rust et al 2006). Any patient receiving anticoagulant medication should have a CT head scan whilst in the ED to rule out ICH. This has been reflected in the NICE head injury guidelines (2014).

Patients who are on anti-coagulant medication are also at a higher risk of developing a delayed ICH, despite a normal initial CT head scan. Multiple studies performed highlight the incidence of delayed ICH in patients on anticoagulants who have sustained a head injury (McCammack et al 2015, Parra et al 2013, Peck et al 2011 and Kaen et al 2010).

A study by Menditto et al (2012) into the prevalence of delayed ICH in anticoagulated patients, found that 6% (5/87) of patients who had had a normal initial CT scan, then had an ICH on a repeat CT 24 hours later. Out of these 5 patients, 1 patient required neurosurgery. 2/82 were re-admitted to ED (on day 2 and day 8) post head injury and were found to have delayed ICH on 3rd CT head, neither required neurosurgery.

Nishijima et al (2012) reports 4/687 (0.6%) were found to have delayed ICH post head injury, 2/4 the ICH was inoperable and the patients did not survive, the other 2 patients did not require neurosurgery and survived.

When considering this evidence, it could be argued that every patient on anticoagulants who sustains a head injury should have an initial CT head scan and a further repeat CT after a set period of time. This would however have significant implications on not only cost and time, but also to the health of the patient. Brenner & Hall (2007) highlight the risk of CT head scans to the patient. With each CT head scan there is between 0.08%-0.01% risk of developing cancer (although this risk drops dramatically with increasing age). Therefore, repeating CT head scans in order to detect delayed ICH may not always represent the optimal management strategy for this group of patients.

There have been a number of studies performed to find the most reliable predictor of delayed ICH, below are the factors found to most frequently be associated with delayed ICH (Auer & Wurm 2012, Pieracci et al 2007, Sharif-Alhoseini et al 2011, Nishijima et al 2013 and Brewer et al 2011):

  • INR level
  • Headache
  • Loss of conscious associated with amnesia
  • Alcohol
  • Vomiting
  • Abnormal mental status

Interestingly, Claudia et al (2011) determined that an INR level of 2.43 and above was the cut off for strongly predicting ICH with a sensitivity of 92% and specificity of 66%.

These are all indicators of increased risk of ICH, however the absence of any of these factors cannot rule out a delayed ICH.

Now what?

The studies show that less than 1% of the patients seen in the ED who have sustained a head injury and are on anticoagulants will go on to develop a delayed tICH that requires neurosurgery or may lead to death.

In order to prevent fatalities in anticoagulated head injury patients, it would be necessary to admit all and repeat a CT head scan every 24 hours. The latest delayed ICH detected is eight days post injury (Menditto et al 2012); therefore it would be necessary to admit all patients for a total of eight days. This strategy is both impractical and also potentially harmful to the patient.

Brenner & Hall (2007) highlights the risk of CT scans and developing cancer. With each scan increasing the risk of cancer by 0.08-0.01%. If a patient then had repeated CT scans for 8 days their risk of cancer would rise to 0.6%-0.08% (the lower risk for patients aged >65 years, the lower percentage for those <1 year). The majority of people on anticoagulants are over 65 years. The risk of patients developing an infection in hospital is greater than in their own home and patients who have social packages also have the risk of losing that package once admitted to hospital.

With these factors and the risk of developing cancer being essentially equal to that of not detecting a delayed ICH which could prevent death (0.3-0.9% based on the two studies discussed), it is not beneficial to the patient to remain in hospital in order to detect a potential delayed ICH.

In this circumstance it would be advised to discharge the patient home post negative initial CT head scan, with either family or friends to observe for a period of time and with adequate safety netting advice, to return if any signs of delayed ICH. The exception to this may be if the patients INR level is raised they would need admitting for a period of observation and if indicated, a repeat CT head.

                                                                                                            Aimée Wright

Emergency Medicine ACP



Auer, C & Wurm, G (2012) Outcome after acute head trauma needing neurosurgical intervention in patients with oral anticoagulants or anti-thrombotic agents. Journal of Trauma and Treatment 1 (4): 1-4

Brenner, D & Hall, E (2007) Computed tomography – An increasing source of radiation exposure. The New England Journal of Medicine 357: 2277-2284

Brewer, E., Reznikov, B., Liberman, R., Baker, R., Rosenblatt, M., David, C & Flacke, S (2011) Incidence and predictors of intracranial haemorrhage after minor head trauma in patients taking anticoagulant and antiplatelet medication. Journal of Trauma 70 (1): 1-5

Claudia, C., Claudia, R., Agostino, O., Simone, M & Stefano, G (2011) Minor head injury in Warfarinised patients: indicators of risk for intracranial haemorrhage. Journal of Trauma 70 (4): 906-909

Kaen, A., Jimenez-Roldan, L., Arrese, I., Delgado, M., Lopez, P., Alday, R., Alen, J., Lagares, A & Lobato, R (2010) The value of sequential computed tomography scanning in anticoagulated patients suffering from minor head injury. Journal of Trauma 68 (4): 895-898

McCammack, K., Sadler, C., Guo, Y., Ramaswamy, R & Farid, N (2015) Routine repeat head CT may not be indicated in patients on anticoagulant/antiplatelet therapy following minor mild traumatic brain injury.  Western Journal of Emergency Medicine 16 (1): 43-49

Menditto, V., Lucci, M., Polonara, S., Pomponio, G & Gabrielli, A (2012) Management of minor head injury in patients receiving oral anticoagulant therapy: A prospective study of a 24- hour observation protocol. Annals of Emergency Medicine 59 (6): 451- 455

National Institute for Health and Care Excellence (2014) Head Injury. Triage, assessment, investigation and early management of head injury in children, young people and adults. London

Nishijima, D., Offerman, S., Ballarad, D., Vinson, D., Chettipally, U., Rauchwerger, A., Reed, M & Holmes, J (2012) Immediate and delayed traumatic intracranial haemorrhage in patients with head trauma and pre-injury Warfarin or Clopidogrel use. Annals of Emergency Medicine 59 (6): 460-468

Nishijima, D., Offerman, S., Ballard, D., Vinson, D., Chettipally, U., Rauchwerger, A., Reed, M & Holmes, J (2013) Risk of traumatic intracranial haemorrhage in patients with head  injury and preinjury Warfarin or Clopidogrel Use. Academic Emergency Medicine 20: 140-145

Parra, M., Zucker, L., Johnson, E., Gullett, D., Avila, C., Wichner, Z & Kokaram, C (2013) Dabigatran bleed risk with closed head injuries: are we prepared? Journal of Neurosurgery 119: 760-765

Peck, K., Sise, C., Shackford, S., Calvo, R., Sack, D., Walker, S & Schechter, M (2011) Delayed intracranial haemorrhage after blunt trauma: are patients on preinjury anticoagulants and prescription antiplatelet agents at risk? Journal of Trauma 71 (6): 1600-1604

Pieracci, F., Eachempati, S., Shou, J., Hydo, L & Barie, P (2007) Degree of anticoagulation, but not Warfarin use itself, predicts adverse outcomes after traumatic brain injury in elderly trauma patients. Journal of Trauma 63 (3): 525-530

Rust, T., Kiemer, N & Erasmus, A (2006) Chronic subdural haematomas and anticoagulation or anti-thrombotic therapy. Journal of Clinical Neuroscience 13 (8): 823-827

Sharif-Alhoseini, M., Khodadadi, H., Chardoli, M & Rahimi-Movaghar, V (2011) Indications for brain computed tomography scan after minor head injury. Journal of Emergencies, Trauma and Shock 4 (4): 472-476

Velmahos, G., Gervasini, A., Petrovick, L., Dorer, D., Doran, M., Spaniolas, K., Alam, H., De Moya, M., Borges, L & Conn, A (2006) Routine repeat head CT for minimal head injury is unnecessary. Journal of Trauma 60 (3): 494-499

5 thoughts on “Head injury and anticoagulation

  1. Zaw says:

    this study – was it based on only warfarin ? Any other anticoagulants?

  2. rob fenwick says:

    This work was based around warfarin. There was an interesting study in the Annals of Emergency Medicine in 2012 looking at delayed bleeds in patients receiving clopidogrel and warfarin (with some surprising findings). The pubmed link is below and should have an open access link:


  3. Suzanne says:

    Do you alter the duration of observation by relative/friend other than the usual 24hrs?

  4. rob fenwick says:

    Not personally although local guidelines may vary on this. I think a discussion involving the patient and carer, which explains that “signs may develop up to 8 days after an injury, however studies show this is incredibly unlikely”, is the way forward.

  5. Anonymous says:

    Great article! Very thorough analysis and conclusion. Thanks!

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