[Urinary ascites and perirenal urinoma - a renoprotective "Complication" of posterior urethral valves].

We report on a male newborn with urinary ascites and perirenal urinoma due to calyceal rupture caused by bladder outlet obstruction and posterior urethral valves. Despite the presence of left-sided high-grade reflux, the "pop-off" mechanism occurred in the non-refluxing right kidney. Impressive normalization of the upper urinary tract anomalies and renal function occurred after surgical treatment of the valves and removal of obstruction.