Significance of peritoneal fluid identified by ultrasonographic examination in children with acute abdominal pain.

The purpose of this study is to evaluate the prevalence of free peritoneal fluid in children with abdominal pain, identify conditions associated with this finding, and determine the ability of ultrasonography to detect associated abnormalities. Two hundred and fifty children with acute abdominal pain and a reference group of 50 asymptomatic children were evaluated for the presence of free peritoneal fluid. Free peritoneal fluid was noted in 72 (29%) symptomatic and three (6%) asymptomatic children. A specific diagnosis was established in 39 (54%) symptomatic children. The discharge diagnosis in the remaining 33 (46%) children was abdominal pain or gastroenteritis of unknown origin. Ultrasonography suggested the correct diagnosis in 29 out of 39 (74%) symptomatic children in whom a specific diagnosis was established at the time of discharge from the hospital. The presence of free peritoneal fluid detected by an ultrasonographic examination in children who have abdominal pain represents a nonspecific finding. Fluid is noted in association with a variety of abdominal and pelvic disorders. In approximately one half of symptomatic children with free peritoneal fluid, the final diagnosis is abdominal pain or gastroenteritis of unknown etiology. In the remainder, ultrasonography aids in the determination of a specific diagnosis.