An anorectal fistula, also called a fistula-in-ano, is an abnormal condition where a person develops a passage from his anus to the surface of the skin surrounding the anus. Alternatively, an anorectal fistula may travel from the anal canal to the vagina, bowel, liver, or other pelvic organs. The condition is most common in people suffering from such illnesses as Crohn's disease, diverticulitis or tuberculosis; it also may present as a birth defect in infants or be caused by an injury to the anus. One of the major causes of an anorectal fistula is an anorectal abscess.
If an anorectal abscess is opened through surgery, an anorectal fistula may develop. Likewise, anorectal fistulas can occur if an anorectal abscess has drained spontaneously. In both cases, the abscess is typically formed by blocked anal glands which are unable to drain properly into the anal canal.
Anorectal fistulas may be painful, but they are not commonly life-threatening. They can be accompanied by symptoms of itching, discharge of pus, and a visible opening in the perianal skin. In some cases, feces may be diverted from the anus to the opening of the fistula. Anorectal fistulas are more common in people suffering from cancer, Crohn's disease, or diverticulitis.
Treatment for anorectal fistula typically includes surgical and non-surgical options. Surgery for anorectal fistula repair involves cutting the fistula open and either excising the entire fistula tract or removing only the tissue lining the fistula tract. A cutting seton, a long tube, can also be inserted to slowly cut through the fistula over time. With surgical treatment, scarring is common. Bowel incontinence can result if the sphincter muscle has been sufficiently damaged, and incontinence of flatus may also develop.
Non-surgical anorectal fistula repair can include the use of biologic plugs or fibrin glue. These treatments seek to heal the fistula from the inside out by plugging the passage with a sterile biodegradable substance. Alternatively, a drain may be used to discharge pus. This final option is unlikely to cure the fistula, but can provide some relief.
Pilonidal cysts are unrelated to anorectal fistulas, but they share some of the same symptoms. Pilonidal cysts may be caused when the area surrounding an ingrown hair in the cleft between the buttocks becomes infected. Pain, redness, and drainage of pus may appear at the infected site. Several factors can contribute to the development of pilonidal cysts. Doctors advise people prone to developing this condition to remove excess hair from the area and maintain a healthy weight.