Ureteral valves.

Ureteral valves together with stenosis and diverticula represent congenital malformations of the ureteral tract between the pyeloureteral junction and the ureterovesical junction. They are rare malformations and even more rarely they cause an obstacle to urine flow. The proximal subjejunal ureteral tract is more frequently involved. The most reliable pathogenetic hypotheses suggest a delay in the canalization of fetal ureter or an ischemic damage. The true ureteral valves should be distinguished from Ostling embryonic folds that can be documented in 5% of newborns and disappear with growth. Treatment, when necessary, consists in the resection of the affected ureteral tract followed by ureteral or pelviureteral end-to-end anastomosis.