Congenital ureteral valves in children: case report and review of the literature.

Congenital ureteral valves are a rare cause of ureteral obstruction. While only 17 pediatric cases have been reported in the literature, this condition should be considered in the differential diagnosis of the child with upper urinary tract obstruction. The pediatric cases are reviewed, and we present an additional case in which unilateral hydronephrosis caused by a ureteral valve was first detected by ultrasound in utero.