Abstract
Objective: This study was intended to set cut-off values for serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as criteria for performing abdominal enhanced computed tomography (CT) in the diagnosis of blunt liver injury.
Method: Among patients with blunt trauma who were transported to the Teikyo University Trauma and Critical Care Center between January 1993 and April 2006, 1,018 cases who were brought in within 3 hours after injury and underwent abdominal enhanced CT were examined. Their medical records were investigated to determine age, gender, AST, ALT, injury severity score (ISS), the mechanism of injury, outcome (alive or dead), liver injury detected or not detected on CT and whether or not invasive procedures or laparotomy were performed when liver injury was found.
Results: Liver injury was detected on CT in 191 of the 1,018 patients examined. The median values of AST, ALT, ISS and age were 350 IU/1, 261 IU/l, 22 and 27, respectively, in patients with liver injury and 55 IU/l, 40 IU/l, 17 and 35, respectively, in those without liver injury. Significant differences in AST, ALT, ISS and age were found by the Mann-Whitney U-test between patients with and without blunt liver injury (p<0.001).
When the cut-off values obtained of AST and ALT were set at 165.5 IU/l and 130 IU/l respectively using the receiver operating characteristic (ROC) curve analysis, a good balance between sensitivity and specificity was obtained. AST showed a sensitivity of 88.0%, specificity of 83.0%, positive predictive value (PPV) of 54.4%, negative predictive value (NPV) of 96.8% and area under the curve (AUC) of 0.920. For ALT, the sensitivity as 83.8%, specificity 86.8%, PPV 59.5%, NPV 95.9% and AUC 0.928. Twenty patients with AST < 165.5 IU/l and ALT < 130 IU/I had liver injury but none of these patients died of liver injury. One of these 20 patients underwent transcatheter arterial embolization (TAE) for liver injury, and another one patient underwent laparotomy related to the liver injury.
Conclusion: The values of AST and ALT could be a useful marker to exclude severe blunt liver injury that requires intervention or laparotomy.
