Intraperitoneal rupture of an infected urachal cyst: a rare cause of peritonitis in children.

Intraperitoneal rupture of an infected urachal cyst is a rare cause of peritonitis in children, and has previously been reported in four children. We report this condition in a 34-month-old toddler who presented with a two-week history of abdominal pain and four days of infraumbilical swelling and erythema. Abdominal ultrasonography (US) and computerized tomography (CT) scan with contrast were helpful in the preoperative evaluation, showing an inflammatory process involving the anterior abdominal wall. The child was treated with intravenous antibiotics, and the infected urachal cyst, other parts of the urachal remnant, and a small portion of the dome of the bladder were excised. The postoperative hospital course was uncomplicated. Because of its rarity and variable manifestations, prompt diagnosis depends on maintaining a high index of suspicion. This diagnosis should be entertained in children with peritonitis in association with umbilical and midline abdominal abnormalities.