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Focused assessment of sonography in trauma (FAST) has been shown useful to detect clinically significant hemoperitoneum in adults, but not in children. Several studies, including a meta-analysis have attempted to assess the performance of FAST in identifying children with intra-abdominal injuries (IAIs) from blunt abdominal traumas (BAT).
In a prospective observational study on 357 children with blunt abdominal trauma, FAST sensitivity = 52% for significant hemoperitoneum, specificity = 96%, PPV = 48%; NPV = 97%. In the meta-analysis, the identification of hemoperitoneum using FAST protocol (for intra-peritoneal fluid only) the pooled estimate of sensitivity was 80% and specificity 96%. For the identification of any IAI using FAST protocol the pooled estimate of sensitivity was 66% and specificity was 93%.
Bottom line:
In children with BAT, FAST has a low to moderate sensitivity but high specificity to detect clinically important free fluid. While a positive FAST suggests hemoperitoneum and abdominal injury, a negative FAST cannot be used to reliably rule out IAI.
References:
1. Holmes J F, Gladman A, Chang C H. Performance of abdominal ultrasonography in pediatric blunt trauma patients: a meta-analysis. Journal of Pediatric Surgery 2007; 42(9): 1588-1594.
2. Fox JC, Boysen M, et al. Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma. Acad Emerg Med. 2011 May;18(5):477-82.