Acute perirenal extravasation of urine in an infant with non-refluxing megaureter.

Perirenal extravasation of urine is a rare event in congenital uropathies, mostly observed perinatally in the case of infravesical obstruction. We describe a male infant with a primary non-refluxing obstructive left megaureter who developed an acute perirenal extravasation and ascites at the age of 4 weeks. After temporary upper urinary diversion, ureterocystoneostomy was successfully performed. Intraoperatively, the distal ureter showed an extremely narrow lumen over a distance of 3 cm. In the current literature, postnatal management of primary megaureters is preferably conservative. Our patient demonstrates an extremely rare complication demanding early surgical intervention.