Urachal Abnormalities
The urachus is a fetal structure that extends up from the top of the bladder to the lower part of the umbilicus (belly button). While it may remain open throughout life, the urachus usually collapses and becomes occluded after birth. The urachus may produce symptoms if some or all of it remains open after birth. If the entire structure is open urine may pass from the bladder to the umbilicus. More commonly, fluid collections called cysts and sinuses develop along its course. Occasionally, infants with a persistently draining urachus have some type of bladder emptying problem. A voiding cystourethrogram (VCUG, x-ray after injecting dye into the bladder) is helpful in diagnosing such emptying problems. A persistently open urachus may also cause bladder infections.
Urachal cysts may occur anywhere along the course of the urachus from the bladder to the umbilicus and may not be detected in infancy, instead causing symptoms in older children or adults as an enlarging lower abdominal mass. Infection of a urachal cyst and the resulting abscess (pus collection) may produce a painful and red area in the middle of the lower abdomen along with fevers. Urachal abscesses may drain through the umbilicus, rupture into the abdominal cavity, or cause a spreading infection of the abdominal wall. These abscesses are uncommon in infants but more common in children, adolescents, and young adults. Urachal abscesses should be drained promptly. Removal of the cyst is usually necessary after infection has resolved. In most cases urachal cysts should be removed along with the rest of the urachal tract using either an open or a laparoscopic approach.
Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.