Anal Fistula

What is an Anal Fistula?

An anal fistula is an abnormal connection or tunnel between two areas in the anorectal region.  The most common cause of anal fistulas is from a blocked mucus gland at the anorectal junction. The gland then becomes inflamed, and in an effort to expel its infected contents, expresses itself, usually as an abscess. As with hemorrhoids, the collection of fluid within a fixed area and the associated inflammation, becomes exquisitely tender. You may have systemic signs of illness, including fever. Once the abscess either drains spontaneously or is incised (cut open) and allowed to drain, the pain diminishes. However, a connection between the offending crypt and the outer opening, seen usually in the perianal region, may remain. Occasionally, the outer opening remains in the rectum, and the abscess and the fistula can only be identified by an examination, often under anesthesia. Rarely, the origin of the infection stems from the abdomen or pelvis, as in diverticulitis.


How do you know you have an Anal Fistula?

 You will notice pus coming from a hole beside your anus. This is the hole where the abscess popped all by itself or where your doctor drained it with a scalpel or scissors. Sometimes there are more than one hole.  The opening of the anal gland that becomes infected is about an inch inside the anus. Bacteria get into the gland and cause an infection. The gland opening is connected to the external opening by a track and infection in the track makes pus.

Will the Fistula heal on its own?

An anal fistula will not heal on its own. It requires some sort of surgery to treat it. The fistula is fed by bacteria in the rectum getting in to the track and causing an infection there. A procedure can be done to stop bacteria getting into the track and close the track as it passes through the anal sphincter.

How is an Anal Fistula Treated?

Treatment for an anal fistula depends on how deep the fistula goes. If it is just under the skin, the fistula can be opened up and allowed to heal. This is a Fistulotomy. It is the most successful way of treating a fistula. Fistulas that go through the sphincter muscle are usually not opened because this would mean cutting the sphincter muscle, and this might lead to loss of control of gas or stool.

Deeper fistulas that go through the muscle are treated by surgery. There are usually two steps.

  • Put a seton into the track. A seton is a piece of surgical thread. It can be used to keep the fistula open and allow it to drain. This is inserted with the patient asleep. A probe is passed through the external opening to find the internal opening. A seton is then pulled through the track and tied in a circle. This is a soft drain that is well tolerated.
  • After 6 weeks a repair of the fistula can be done. This is more involved. It is illustrated in the pictures. 

A. The internal opening is cleared. Small flaps are made to expose the muscle of the internal sphincter.

B. The internal sphincter is closed with deep stiches.

C. The flaps are closed.

D. The final result

Other Types of Anal Fistula

There are three other specific types of anal fistula:

  1. Rectovaginal Fistulas
  2. Pouch anal and Pouch vaginal fistulas
  3. Fistulas in Crohn’s disease

These are more complicated than typical anal fistulas and harder to fix

Rectovaginal fistulas

Fistulas from the anus to the vagina usually follow childbirth and are fixed by repair of the muscles that were damaged. Rectovaginal fistulas due to an infected anal gland can be repaired the same way as anal fistulas but may need reinforcement of the muscles in the area.

Pouch anal and pouch vaginal fistulas

Fistulas from a pouch constructed to replace the rectum in patients with ulcerative colitis and familial polyposis can come from the join up (anastomosis) of the pouch to the anus or from an infected anal gland. These are sometimes difficult to repair and sometimes the pouch needs to be moved down to cover the fistula. Fistulas from the pouch to the vagina happen quite frequently and may need multiple operations to fix.

Fistulas in Crohn’s disease

Patients with Crohn’s disease often develop disease near the anus that includes fistulas. Some of the fistulas are similar to those found in patients without Crohn's, and these can be repaired in the same way. Other fistulas occur in the setting of Crohn’s disease in the tissues around the anus. These patients need biologic therapy to control the Crohn’s disease before surgery to repair the fistula. 

Next Steps

The Division of Colorectal Surgery dedicated Anal Fistula Center has extensive experience in treating simple and complex anorectal fistulas. Fistulotomy, seton placement, advancement flap repair and LIFT procedures are performed by our surgeons and are individualized to the patient depending upon the nature and location of the fistula.

If you or someone you love is in need of care for an anal fistula issue, we’re here to help. Our team is available for consultations, second opinions, and to perform any colorectal procedure, should one be necessary. Call us at (212) 342-1155 or request an appointment online.