Giant diverticulum of the bladder simulating ovarian cyst.

A patient was admitted for investigation of a giant ovarian cyst, confirmed by physical examination. At laparotomy the genital organs appeared normal. Ultrasonic reexamination affirmed the preliminary findings of a pelvic cystic mass. A urinary bladder diverticulum was suspected and confirmed by cystography and found to be nonobstructive in nature. Although extremely rare, bladder diverticulum should be considered in the differential diagnosis of a cystic pelvic mass.