Ureteral obstruction due to retroperitoneal fibrosis secondary to a solitary internal iliac aneurysm.

We report a case of ureteral obstruction due to retroperitoneal fibrosis secondary to a solitary left internal iliac aneurysm. It has been reported that as a cause of ureteral obstruction, an internal iliac aneurysm without aortic and/or common iliac aneurysms is very rare. In the present case, magnetic resonance imaging was a useful modality to diagnose retroperitoneal fibrosis secondary to an internal iliac aneurysm as a direct cause of ureteral obstruction.