The encased ureter: bullet and bodkin pattern, a reliable radiographic sign.

Among the causes of constricted ureter is benign or malignant encasement. The diagnosis of ureteric encasement is frequently overlooked, even by well informed clinicians and radiologists. The most common benign cause is retroperitoneal fibrosis and the most frequent malignant causes are extension from an adjacent primary tumour, true metastases to the ureter and lymphoma. Lack of recognition of the process may lead to mistaken diagnosis of an inflammatory stricture or infiltrating transitional cell tumour, with resultant inappropriate management. A sign which appears to be almost specific for encasement, the bullet and bodkin configuration, is described here. Newer imaging modalities such as computed tomography and ultrasound, while helpful, are probably less sensitive and less specific than the retrograde ureterogram because a detectable mass is not always present.