Comprehensive Imaging Review of the Ureter.

The ureter is an important conduit between the kidney and the bladder and is frequently imaged to rule out cancer in the upper genitourinary tract. However, while malignancy can occur, a spectrum of other pathologic ureteral findings can exist, and these can be divided into congenital, intrinsic, and extrinsic abnormalities that range from postoperative and neoplastic conditions to inflammatory disease. This article provides a comprehensive overview of the ureter, including the ureteral anatomy, ureteral imaging strategies, and various ureteral conditions and their associated imaging features. It is important to identify congenital genitourinary variants, as these are frequently linked to further imaging recommendations, such as nuclear medicine renography and fluoroscopic voiding cystourethrography. Intrinsic abnormalities can be iatrogenic, infectious, inflammatory, or neoplastic. Intrinsic ureteral strictures are most commonly iatrogenic, usually resulting from prior surgery or radiation therapy. Ureteral infections include tuberculosis, schistosomiasis, and Escherichia coli infection, which have varying imaging manifestations. Inflammatory conditions include ureteritis cystica and pseudodiverticulosis. Ureteral masses are rarely benign and are most commonly urothelial carcinomas. Processes in the abdomen and pelvis, including mass effect from pregnancy, ureteral compression from advanced pelvic floor prolapse, and rarely, ureteral obstruction from vaginal devices, also can affect the ureter. The ureter can be injured during pelvic surgery or trauma. It also may be involved by deep pelvic endometriosis, mass effect from extrinsic lesions, or reactive change from inflammatory processes. Radiologists need to have a clear understanding of the patient's history and the range of possible ureteral conditions to establish the optimal differential diagnosis.