Pelviureteric obstruction in childhood.

Pelviureteric junction obstruction is a common cause of intra-abdominal mass in childhood. The diagnosis is usually apparent when the characteristic signs of obstruction are seen at intravenous urography. A voiding cystourethrogram should be performed to exclude vesicoureteral reflux as the underlying condition. Obstruction may be further assessed by a diuretic load or by pressure-flow studies.