Background and importanceFocused Assessment with Sonography for Trauma (FAST) has attracted attention for its use in the detection of intraabdominal pathology. However, Computed Tomography (CT) remains the gold standard for the assessment of blunt torso trauma. ObjectiveThe study examines the effectiveness of FAST both in the detection of intraabdominal pathology in pediatric patients (< 19 years) and in the assessment of the need for CT for further examination. DesignThe study was designed as a retrospective observational investigation of diagnostic value.SettingThe pediatric patients who were admitted to the emergency department with blunt torso trauma between January 2013 and October 2016 were included in the study. The sample of the study comprised 255 patients who met the inclusion criteria.Outcome measures and analysisThe demographic data, vital findings, trauma mechanism, physical examination findings, the presence of a concomitant trauma, laboratory findings, CT scans of the thorax and abdomen, FAST findings, and patient outcomes were recorded. The Chi-square test and Fisher’s exact test were used for comparisons. A logistic regression model was developed to determine the variables that independently affect the agreement between FAST and CT.Main resultsThe comparison of FAST and CT revealed a poor agreement in pediatric patients with blunt torso trauma. The agreement was negatively affected by the severity of trauma and the presence of concomitant trauma. The error rate of FAST increased by five-fold especially in the presence of concomitant thorax trauma. However, FAST had a good negative likelihood ratio.ConclusionFAST was determined to yield accurate results when used in stable patients, thus revealing it as an appropriate tool for the initial examination of stable pediatric patients with blunt torso trauma. For unstable patients, however, a negative or positive FAST examination should not guide the decision to use CT and CT should remain a standard tool for further examination. FAST should not be regarded as an equivalent or complementary tool to CT. It is, instead, a noteworthy negative predictor in pediatric patients. A positive FAST result can serve as a predictor of the need for operation and hospitalization in multiple trauma patients.