An anal fistula is an abnormal channel or tunnel-like lesion that starts inside the anus and ends outside on the skin of the buttocks. Its development is usually the result of a previous anal infection or abscess. About 50% of people with an anal abscess end up with a fistula.
Surgery is the only means of curing fistulas. Surgery to correct a fistula is called fistulotomy.
The patient is positioned on the table so that the anus and rectal area are exposed. This can be done in either of two positions: face down, with the buttocks slightly elevated, or supine (on the back) with the legs held up in stirrups. After anesthesia is administered, the anal area is cleaned with an antiseptic solution.
In this procedure, the surgeon opens the fistula tunnel. To accomplish this, a small portion of the anal sphincter usually is cut. Once the tunnel is open, it is then converted to a groove, which allows the fistula to heal from the inside out. Stitches are generally not needed and a dressing may be put in place.
If the abscess is still present, the fistulotomy may be postponed until the abscess is drained and healed.
A very shallow or small fistula can be treated in a doctor's office, using local anesthesia. Larger fistulas are operated on in the hospital, using spinal or general anesthesia. If the fistula is very deep and penetrates more than one sphincter, multiple procedures may be necessary.