Surgery is chiefly required when diverticulitis fails to respond to treatment. This is done by draining any collections of pus and removing the segment of the colon (especially the sigmoid colon) surgically from where the diverticula are. In the case of persistent bleeding diverticula, surgical removal will be required. Also, surgery will be necessary if the diverticula erodes into other organs (like the adjacent bladder/colovesical fistula), leading to severe recurrent urine infections and gas passage when urinating.