A colovesical fistula is a complication of diverticulitis, and complicated diverticulitis needs surgery. Bowel rest and antibiotics alone (A) will not close the fistula. The diseased sigmoid is resected, the bladder defect is closed, and in this elective setting a one-stage resection with primary anastomosis is done. Removing every diverticulum (C) or doing only a cystoscopic fistulectomy (B) leaves the diseased colon behind.