Head injury and unclear mechanism of injury: initial hematocrit less than 30 is predictive of abusive head trauma in young children

Purpose: Head injury secondary to abusive head trauma (AHT) is a major cause of morbidity and mortality in susceptible young infants and children. Diagnosing AHT remains challenging and is often complicated by a questionable mechanism of injury. Concern of ionizing radiation risk to children undergoing head CT imaging warrants a selective approach. We aimed to evaluate initial findings that could direct further investigation of AHT.

Methods: A retrospective review of the trauma databases at a two level one pediatric trauma centers was performed. We reviewed all patients age five years and under with a diagnosis of traumatic brain injury (TBI) from 2002-2011.

Results: A total of 1129 patients (mean age 1.7 ± 1.7 years; 64% male) with TBI were identified, 429 (38%) of which were the result of AHT. Complete data was available for 921 patients (82%) and were included in statistical evaluation. Forty-eight percent of patients in the AHT group had a hematocrit ≤ 30% on presentation compared to 19% of patients in the non-AHT group. On univariate analysis, a hematocrit of ≤ 30% was predictive of AHT as the cause of injury (P<.0001), as was a platelet count of greater than 400,000 (P<.0001). After controlling for age, sex, ISS, GCS on presentation, need for CPR, and survival to hospital discharge, hematocrit of ≤ 30% and platelets of greater than 400,000 were predictive of AHT as the cause of TBI (P<.05).

Conclusions: In the setting of head injury and unclear history of trauma, a hematocrit of ≤ 30% on presentation increases the likelihood of abusive head trauma in children up to the age of 5 years.