To determine the location of intraperitoneal free fluid on FAST exam in pediatric patients undergoing evaluation for trauma.

Retrospective review of all FAST exams positive for intraperitoneal free fluid performed in patients sustaining trauma between August 2009 and February 2016 in an urban pediatric emergency department. Positive results were categorized into one of nine potential intraperitoneal locations; 4 each in the right and left upper quadrants, and the pelvis.

One hundred and three complete positive studies were reviewed. The median age of patients was 10years (IQR 7–14) with 66% being male. Ninety-five percent had fluid present in the pelvis, 35% had fluid present in the RUQ, and 16.5% had fluid present in the LUQ. Overall, the most frequent location of fluid outside of the pelvis was found at the inferior tip of the liver, present in 83.3% of patients with fluid in the RUQ and 29% of all patients with a positive FAST.

The majority of pediatric trauma patients with a positive FAST exam will exhibit free fluid in the pelvis. Particular attention should be directed to the inferior tip of the liver in children as this represents the most common location for fluid collection outside the pelvis.