To validate the F-AST score as a CT decision tool in pediatric blunt abdominal trauma: A prospective diagnostic accuracy study.

INTRODUCTION

Focused assessment with sonography for trauma (FAST) is a valuable tool in managing adult trauma patients but has poor utility in children due to its poor sensitivity. Multiple studies have explored the addition of liver enzymes to improve the diagnostic accuracy of FAST in pediatric blunt abdominal trauma (BAT) patients. A retrospective study at our institute used FAST findings with liver enzymes (F-AST score) to rule out Intra-Abdominal Injury (IAI) in pediatric BAT patients, concluding that normal liver enzymes and a negative FAST scan can effectively rule out IAI. This study aimed to validate the F-AST score (FAST + Aspartate Transaminase) as a screening tool for identifying IAI in pediatric BAT and compared it with the FAST examination.

METHOD

A prospective diagnostic accuracy study was conducted at a single center from August 2020 to April 2022. It included patients under 14 years old with blunt abdominal trauma (BAT) within 8 h of injury who had a positive FAST scan, a dangerous injury mechanism, or clinical signs of intra-abdominal injury (IAI) or peritonitis. Patients in cardiac arrest, needing damage control surgery, or with chronic liver or kidney diseases were excluded. Participants underwent liver enzyme tests (AST) and FAST examinations, followed by a computed tomography (CT) scan. The diagnostic accuracy of the F-AST score was then compared to the CT findings, which served as the gold standard.

RESULTS

A total of 125 patients were recruited for the study. FAST was positive in 12.8 % (n = 16) of the patients. FAST alone had a sensitivity of 52.9 % in detecting BAT. Whereas, the F-AST score was found to be 94 % sensitive and 63 % specific in identifying IAI in contrast enhanced CT (CECT) abdomen. The negative predictive value (NPV) increased to 98.6 % and the negative likelihood ratio (NLR) decreased to 0.093 using the F-AST score. The receivers operating characteristics curve (ROC) curve analysis for the F-AST score was found to be excellently accurate (95 % CI:0.754-0.943, p < 0.001). The most common injured organ was found to be the liver (n = 11).

CONCLUSION

The F-AST score, incorporating both FAST findings and AST levels, improves sensitivity and negative predictive value over FAST alone in identifying intra-abdominal injuries. Patients with a F-AST score of zero may be safely observed in the emergency department, potentially avoiding unnecessary CT scans. However, further prospective trials are warranted for validation.