Roughly 50% of patients with an abscess form a fistula. A fistula is an infected tunnel between the anus or rectum and skin of the buttocks. Should a fistula develop or previous abscess drainage be unsuccessful, a fistulotomy will be performed to mitigate the disease.

A fistulotomy is an outpatient procedure that is typically performed under intravenous and local anesthesia. During the procedure, a surgeon will open the fistula and remove its contents before stitching the tunnel closed. If the fistula is especially complicated, part of the anal sphincter muscle may need to be cut.

Although safe, a fistulotomy may cause temporary or permanent fecal incontinence. This is a rare occurrence, however, and usually develops if the sphincter muscle has been cut to treat the disease. To lower the risk of fecal incontinence, a surgeon may cut a small amount of the anal sphincter muscle and place a seton. This rubber band-like device encourages drainage and gradual removal of the fistula.