Acute peritonitis caused by intraperitoneal rupture of an infected urachal cyst: report of a case.

Embryologically, the urachus is the tubular structure that connects the dome of the bladder to the umbilicus. Incomplete obliteration of the urachal lumen results in several anomalies. The most common urachal abnormality is the urachal cyst and, while intraperitoneal rupture of an infected urachal cyst is very rare, acute peritonitis resulting from intraperitoneal rupture is the most dangerous of all complications associated with urachal anomalies. We report the case of an 80-year-old woman who underwent an emergency laparotomy for lower abdominal pain and signs of acute peritonitis, which revealed intraperitoneal rupture of an infected urachal cyst. Infected urachal cysts with intraperitoneal rupture are often misdiagnosed as a common acute abdomen and result in emergency exploratory laparotomy. These patients should be managed by complete excision of the urachal remnant to prevent any malignant change occurring, as malignant changes have been reported.