Megaureter and ureteral valves.

Primary megaureter is visualized as a typical dilatation on urography. Adequate oblique projections should be added to depict the juxtavesical tract of normal caliber. In even the most severe forms pyelocaliectasis is absent or mild and the ureter is not tortuous. Sonography as well as fluoroscopy during urography shows hyperperistalsis in the dilated tract and aperistalsis in the juxtavesical tract. Cystography rules out vesicoureteral reflux. In prune-belly syndrome the megaureter is bilateral and massive with no evidence of obstructions. The sonographic finding of hydronephrosis or hydroureteronephrosis and the absence of vesicoureteral reflux on voiding cystography lead to the suspicion of ureteral valves, directly documented on urography as sharp and transverse filling defects. Retrograde pyelography can better define the obstructing area and documents the normality of the underlying tract. With this procedure, the valvular flaps appear with a superior convexity (like a small umbrella). MR-urography still to be validated clinically, will be able to provide novel perspectives.