Test characteristics of focused assessment with sonography for trauma (FAST), repeated FAST, and clinical exam in prediction of intra-abdominal injury in children with blunt trauma.

Abstract

In children with blunt abdominal trauma (BAT), focused assessment of sonography in trauma (FAST) has been reported with low sensitivity, on the whole, in the detection of intra-abdominal injuries (IAI). The aim of the present study was to assess test characteristics of FAST using different strategies including repeated FAST (reFAST), and physical exam findings. This retrospective study evaluated BAT pediatric patients with stable hemodynamics who underwent computed tomography (CT). Demographic data, initial physical examination, and results of FAST, reFAST (if done), and CT imaging were recorded. Different strategies of FAST were cross-tabulated with CT as the gold standard and test characteristics including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were interpreted. 129 patients with a mean age of 8.6 ± 4.7 were studied and 74% were male. Comparing CT-positive and -negative groups, from the demographic and clinical findings, only positive physical exam (tenderness or ecchymosis) was significantly higher in the CT-positive group (59% vs. 17%; p < 0.01). In a multivariate analysis, positive FAST modality and clinical exam remained independent predictors for a positive CT result (likelihood ratios of 34.6 and 6.4, respectively). Out of the different diagnostic strategies for the prediction of IAI, the best overall performance resulted from the FAST-reFAST-tenderness protocol with sensitivity, specificity, PPV, NPV, and accuracy of 87%, 77%, 70%, 91%, and 81%. For children with blunt abdominal trauma, physical examination plus FAST and reFAST as needed, seems to have reasonable sensitivity, specificity, and accuracy in detecting intra-abdominal injuries and may reduce the need for CT scans.