Risk of Delayed Intracranial Hemorrhage in Anticoagulated Patients with Mild Traumatic Brain Injury: Systematic Review and Meta-Analysis. 
Delayed intracranial hemorrhage is a potential complication of head trauma in anticoagulated patients.  Our aim was to use a systematic review and meta-analysis to determine the risk of delayed intracranial hemorrhage 24 h after head trauma in patients who have a normal initial brain computed tomography (CT) scan but took vitamin K antagonist before injury.  EMBASE, Medline, and Cochrane Library were searched using controlled vocabulary and keywords.  Retrospective and prospective observational studies were included.  Outcomes included positive CT scan 24 h post-trauma, need for surgical intervention, or death.  Pooled risk was estimated with logit proportion in a random effect model with 95% confidence intervals (CIs).  Seven publications were identified encompassing 1,594 patients that were rescanned after a normal first head scan.  For these patients, the pooled estimate of the incidence of intracranial hemorrhage on the second CT scan 24 h later was 0.60% (95% CI 0-1.2%) and the resulting risk of neurosurgical intervention or death was 0.13% (95% CI 0.02-0.45%).  The present study is the first published meta-analysis estimating the risk of delayed intracranial hemorrhage 24 h after head trauma in patients anticoagulated with vitamin K antagonist and normal initial CT scan.  In most situations, a repeat CT scan in the emergency department 24 h later is not necessary if the first CT scan is normal.  Special care may be required for patients with serious mechanism of injury, patients showing signs of neurologic deterioration, and patients presenting with excessive anticoagulation or receiving antiplatelet co-medication.