An anal Fistula, commonly the result of an anal abscess – an infection in the mucous-secreting gland in the anal canal, is a small passage connecting the anal gland from which the abscess arose to the skin where the abscess has drained.
An abscess forms when a small gland just inside the anus becomes infected from bacteria or stool trapped in the gland. Conditions such as constipation, diarrhea, colitis, or other inflammation of the intestine may make these infections more likely.
After an abscess has been drained, a passage may remain between the anal gland and the skin, resulting in a fistula. If the gland does not heal, there will be persistent drainage through the passage. If the outside opening of the fistula heals first, a recurrent abscess may develop.
An abscess does not always become a fistula. A fistula develops in up to fifty percent of all abscess cases. There is no way to predict if this will occur. If drainage persists for two to three months, the diagnosis of anal fistulas is made.
Abscesses usually cause intense anal pain and swelling as well as possible fever. Drainage of the abscess, either on its own or with an incision, relieves the pain and pressure. Fistulas are associated with drainage of blood, pus, or mucus, but they are not usually painful. A fistula should not recur if it has healed properly. If your bowels are otherwise normal, you should not develop another fistula.
An abscess is treated by draining the pus through an opening made in the skin near the anus. Often this can be done in the doctor's office using a local anesthetic. A large or deep abscess may require drainage in the operating room. Hospitalization may be necessary for patients susceptible to more serious infections, such as diabetics or people with decreased immunity.
Surgery is usually necessary to treat an anal fistula. This involves cutting a small portion of the anal sphincter muscle to open the passage, joining the external and internal opening, and converting the passage into a grove that will then heal from the inside out. Most fistula surgeries can be performed on an outpatient basis. If the fistula involves too much sphincter muscle, a two-stage procedure or more complicated repair may be necessary.
After fistula surgery, one may experience mild to moderate discomfort for the first week and can be controlled with pain pills. There will be no limitation on activity. Soak the affected area in warm water three or four times a day. Stool softeners may also be recommended. You may need to wear a gauze pad to prevent the drainage from soiling your clothes. Bowel movements will not affect healing.