An unusual cause of free air in the abdomen: emphysematous cystitis with bladder diverticulum perforation.

A 64-year-old male, with a history of chronic urinary outflow obstruction secondary to benign prostatic hyperplasia, presented with haematuria and urinary retention following spontaneous removal of his long-term catheter. The patient was septic on admission and a CT examination of the abdomen and pelvis showed an acutely inflamed urinary bladder diverticulum and extensive intra-abdominal free air. The patient was treated medically for emphysematous cystitis centred on a perforated bladder diverticulum, which was thought to be caused by the underlying infectious/inflammatory process. Alternative aetiologies for free air in the abdomen such a traumatic bladder perforation and gastrointestinal perforation were considered and excluded. The patient responded well to medical management and was discharged after an 11 day in-patient stay.