Intermittent hydronephrosis: a diagnostic challenge.

Intermittent hydronephrosis is a difficult condition to diagnose because of the mild degree of dilatation encountered in imaging studies. The condition nevertheless is disabling and attempts to reach a precise diagnosis include diuretic excretory urography, ultrasonography and renal scans. The delayed double-peak pattern seen on 99mtechnetium-diethylenetriaminepentaacetic acid diuretic renography shows how the ureteropelvic junction can become self-obstructing with forced diuresis. All patients who exhibited this sign eventually had frank obstruction and most exhibited an extrinsic component to the obstruction. The recognition of the double-peak pattern may become a useful adjunct in the early diagnosis of intermittent hydronephrosis.