Hydronephrosis with ureteral valve: diagnosis by ultrasonography and antegrade pyelography.

A case of massive hydronephrosis secondary to a ureteral valve was discovered upon evaluation of mild trauma. The orderly diagnostic studies, including ultrasonography and antegrade pyelography, led to the correct diagnosis and appropriate therapy. Ultrasonography as a diagnostic tool in urology is discussed and characteristics of the 18 cases of ureteral valves reported to date are reviewed.