Written by Clay Smith
A positive FAST exam in hemodynamically stable children with blunt abdominal trauma warrants CT; a negative FAST should not be falsely reassuring that intraabdominal injury (IAI) is absent.
Why does this matter?
A RCT in JAMA in 2017 found that the FAST exam did not change workup or outcome in hemodynamically stable children with torso trauma. What’s the consensus of the literature?
This was a systematic review and meta-analysis of 8 studies, 2,135 total patients, which found FAST had pooled sensitivity of 35%, specificity 96% for IAI. All 8 studies were prospective; 1 of the 8 was the RCT mentioned above. What this means is if the FAST is positive, you need a CT (post-test probability of IAI 63%). If the FAST is negative, you may still need a CT, because the post-test probability of IAI remains stubbornly high at 9%. None of the studies had low enough negative likelihood ratios to obviate the need for CT. However, several other clinical variables may be considered when determining whether to CT or not in children with blunt abdominal trauma. The PECARN blunt abdominal trauma rule is a good place to start.
The Utility of the Focused Assessment With Sonography in Trauma Examination in Pediatric Blunt Abdominal Trauma: A Systematic Review and Meta-Analysis. Pediatr Emerg Care. 2021 Feb 1;37(2):108-118. doi: 10.1097/PEC.0000000000001755.