[Spontaneous urinary extravasation due to chronic ureteral obstruction].

Spontaneous nontraumatic perirenal extravasation of urine is an unusual phenomenon, and the majority of the reported case were caused by acute obstruction with passage of a ureteric calculus. Extravasation due to obstruction of more gradual onset occurs less frequently. We report four cases, three caused by tumor obstruction of the ureter, and one thought to be obstructed by the stricture due to ureteral inflammation. We discuss the diagnosis and treatment of spontaneous urinary extravasation, especially due to chronic ureteral obstruction.