Blunt abdominal trauma in children: how predictive is ALT for liver injury?

The liver is the second most commonly injured intra-abdominal organ in children. CT scanning is currently regarded as the "gold standard" in screening for intra-abdominal injury following blunt trauma. However, the risks associated with performing CT in children are not insignificant and, in addition, CT is not always readily available. This study investigates the utility of alanine aminotransferase (ALT) in screening for liver injury in paediatric trauma.

Two groups of patients were compiled from a prospectively identified trauma registry-one with liver injuries and another with intra-abdominal injuries other than to the liver. Inclusion in the study required that an initial ALT level had been obtained after injury. Where CT had been performed, a paediatric radiologist blind to the ALT results graded the severity of the liver injuries. The study groups were compared and a receiver operating characteristic (ROC) curve generated to derive the optimum ALT threshold to identify liver injury.

51 patients with liver injury and 65 with other intra-abdominal injuries were identified. An ALT level of > or =104 IU/l gave a sensitivity of 96% and a specificity of 80%. When liver injuries were stratified to identify only clinically significant liver injuries (grades III, IV and V), this ALT threshold identified 100% of patients with 70% specificity.

In this sample, ALT appears to be a useful predictor for the presence or absence of liver injury. In haemodynamically stable children with clinical suspicion of isolated liver injury, identification of a normal ALT level (<104 IU/l) may reduce the need for unnecessary transportation for CT scanning with subsequent radiation exposure.