Ureteropelvic fibrosis in renal transplants: radiographic manifestations.

An uncommon cause of late ureteric obstruction in renal transplants is fibrosis involving the allograft pelvis and ureter. Three new cases are reported, emphasizing a characteristic radiographic appearance of marked generalized narrowing of the renal pelvis and ureter with concomitant dilatation and hydronephrosis of the calyceal system. This unique pattern of obstruction is the result of infiltration of the transplant ureter and pelvis by fibrous tissue. Although the exact stimulus that incites this intense fibrotic scarring is unknown, ischemia, rejection episodes, and infection have been implicated. When properly diagnosed, conservative urologic management, with ureteral stenting and dilatation, is usually adequate to maintain transplant function.