An anal fistula is a tunnel that develops between the inner lining of the anal canal and the outside skin around the anus. A fistula will not heal without treatment.
Anal fistulas are the result of an infection that originates in an anal gland, causing an abscess. After the abscess is drained, a small tunnel persists between the infected anal gland and the skin.
Symptoms of an anal fistula can include:
- An opening on the skin around the anus
- A red, inflamed area around the tunnel opening
- Oozing of pus, blood or stool from the tunnel opening
- Pain in the rectum and anus, especially when sitting or passing stool
There are several stages and options in treating an anal fistula:
Some patients will have active infection when they present with a fistula, and this requires healing before definitive treatment can be decided. Antibiotics may be used, but the best way to heal the infection is to prevent the buildup of pus in the fistula, which leads to abscess formation. This may be done with a seton - a length of suture material looped through the fistula which keeps it open and allows pus to drain. The seton has the appearance of a rubber band.
A fistula develops in 40 to 50 percent of all abscesses and there is no reliable way to predict if this will occur.
Definitive treatment of a fistula is designed to stop it from recurring. Treatment depends on where the fistula lies, and which parts of the anal sphincter it crosses. Options include:
- Doing nothing – a drainage seton can be left in place long-term to prevent problems. This is the safest option although it does not definitively cure the fistula.
- Lay-open of fistula-in-ano – this option involves a procedure to cut the fistula open and let it heal naturally. This cures the fistula but leaves behind a scar, which can cause problems with incontinence. This option is not suitable for complex fistula or those that cross the entire anal sphincter.
- Endorectal advancement flap is a procedure in which the internal opening of the fistula is identified, and a flap of mucosal tissue is cut around the opening. The flap is lifted to expose the fistula, which is cleaned before the internal opening is sewn shut. Success rates are variable and high recurrence rates are directly related to previous attempts to correct the fistula.
- LIFT (Ligation of Intersphincteric Fistula Tract) is a procedure utilized for complex and deep fistulas. It involves an Intersphincteric approach to tie off the fistula tract. It does not involve cutting the sphincter muscle.
Complications are rare and seldom serious. Sometimes the control of wind and/or stool is weakened. Very deep fistulas may require alternative treatment. Sometimes an anal fistula can be a sign of inflammation higher up the bowel, called Crohn’s disease. Your physician may request tests to determine this possibility. Depending on the fistula, this small tract may be difficult to close and may require several surgeries to achieve complete closure.