Imaging of the Urachus: Anomalies, Complications, and Mimics

Urachal anomalies are more common than previously thought, with more cases discovered incidentally, because of the increased use of cross-sectional imaging. Although an abnormal persistence of an embryologic communication between the bladder and the umbilicus is often recognized and managed in childhood, it may persist into adulthood, with a greater risk of morbidity. Congenital urachal anomalies that are detected early can benefit from an optimized management including surgical approach with a complete resection of the urachal remnant in cases when spontaneous resolution or medical management has failed. At imaging, the different types of urachal anomalies have a distinct appearance. A patent urachus is recognized as an elongated patent connection between the bladder and the umbilicus. An umbilical-urachal sinus is depicted as a blind focal dilatation at the umbilical end, whereas a vesicourachal diverticulum is a focal outpouching at the vesical end. Urachal cysts are visualized as midline fluid-filled sacs most frequently located near the bladder dome. Complications of urachal anomalies have nonspecific clinical findings and can mimic other abdominal and pelvic processes. Potential complications, such as infection and tumors, should be recognized early to ensure optimal management. Understanding of the embryonic development of the urachus is necessary for the radiologist to diagnose the wide variety of urachal disease. (C) RSNA, 2016