Diagnostic Performance of Ultrasonography for Detecting Intra-Abdominal Free Air in Pediatric Patients With Acute Abdomen at a Pediatric Emergency Care Unit: A Retrospective Study.

This study aimed to investigate the diagnostic performance of ultrasonography in evaluating intra-abdominal free air in pediatric patients with acute abdomen. This retrospective study evaluated pediatric patients with abdominal symptoms who underwent ultrasonography before computed tomography (CT), the gold standard for diagnosing intra-abdominal air. The diagnostic performance of ultrasonography was determined based on this standard. In pediatric patients with intra-abdominal free air, free air sizes (massive or focal), and age were compared between those in whom free air was and was not detected on ultrasonography using Fisher's exact and Mann-Whitney U tests. A total of 240 patients were evaluated. Among the 14 patients with intra-abdominal free air, 10 patients were correctly diagnosed using ultrasonography. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of ultrasonography for detecting intra-abdominal free air were 98.3% (236/240), 71.4% (10/14), 100% (226/226), 100% (10/10), and 98.3% (226/230), respectively. Although the differences were not statistically significant, diagnosis tended to be more difficult in patients with focal free air and older age (massive versus focal free air and ages in patients with ultrasonographically detected versus undetected free air = 6/4 versus 0/4, P = .084; age: 5.2 ± 6.4 years [0-16.7 years] versus 11.6 ± 5.2 years [5.7-16.8 years], P = .089). Ultrasonography has satisfactory diagnostic accuracy for detecting intra-abdominal free air in pediatric patients with acute abdomen, but not all cases are detected. Examiners and physicians should consider further examinations and management for these patients.