The blind-ending ureteral branch typically terminates adjacent to the distal or middle section of the normal branch. It contains all of the normal layers of the ureteral wall, and it terminates either as a dilated bulb or as an atretic stalk.

Because the blind-ending ureter does not drain renal parenchyma, it cannot be seen on excretory studies, such as intravenous pyelogram or contrast-enhanced CT. As a result, retrograde studies are generally required to establish the diagnosis.

An “inverted Y” ureter is the rarest form of incomplete duplication. It occurs when two ureteric buds appear on the mesonephric duct but fuse before reaching the metanephric mesenchyme. As a result, a single renal pelvis is seen, but the ureter divides as it approaches the bladder, such that two distinct ureteric orifices are seen on the affected side. One of the ureteral branches often has an ectopic orifice or forms a ureterocele, resulting in obstruction.