Genitourinary Radiology > Bladder > Urachal Anomalies

Urachal Anomalies


The urachus is an extraperitoneal structure that represents the terminus of the fetal bladder and communicates with the allantois at the level of the umbilicus. It usually closes spontaneously by the middle of the second trimester, leaving the median umbilical ligament as its remnant. The four anomalies of urachal closure include: patent urachus, umbilical urachal sinus, vesicourachal diverticulum, and urachal cyst. Congenital anomalies of the lower urinary tract are often associated with urachal anomalies.

Sagital reconstruction of CT slices through the bladder showing a tubular soft tissue density extending from the anterior aspect of the bladder dome representing a urachal diverticulum (arrow). This is a patent connection to the bladder that is blind ending. If there was contrast in the bladder, this diverticulum with fill with contrast.

Axial (1) and Sagital (2) 3D reconstructions through the bladder containing contrast shows a fluid density structure at the anterior aspect of the bladder dome representing a urachal cyst (arrow). Notice that with contrast in the bladder, this urachal cyst, does not fill with contrast.

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