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Anal Fistulas

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Anal fistulas are abnormal, small channels or connections between the rectum and skin in the anorectal region. Anal fistulas often develop from an acute infection of an anal gland, located inside the anal opening. The infection causes an abscess to form, which then develops into a fistula or channel leading to the outside skin.

Anal fistulas may also be caused by surgery, Crohn's disease, or radiation.

Symptoms of Anal Fistulas

Anal fistulas may appear as swollen inflamed sores near the anus from which pus, clear liquid, stool, or blood may drain. They may also appear as a painful lump near the anus, and can be accompanied by signs of an infection such as fever or chills.

Risk Factors for Anal Fistulas

Individuals with an infection of the anal gland, and/or an abscess often develop fistulas. Individuals with Crohn's disease have a tendency to develop anal abscesses and fistulas.

Diagnosis of Anal Fistulas

Fistula must be carefully diagnosed to determine their exact internal location. A physician will usually use an anoscope, a small instrument used to view the anal canal. Sometimes exams will be performed in the operating room.

If the fistula is complex or in an unusual spot, your physician may also employ a contrast solution or dye, which is injected into the fistula, to display its path. An MRI or endorectal ultrasound may also be performed to visualize the exact location and structure of the fistula.

In order to rule out Crohn's disease or ulcerative colitis, your physician may perform either a colonoscopy or sigmoidoscopy. These tests consist of inserting an endoscope – a flexible, thin tube with a tiny light and camera – into the anus and guiding it through the colon. A colonoscopy allows physicians to view the entire colon or large intestine; a sigmoidoscopy is a smaller instrument and only allows viewing of the lower colon.

Treatment for Anal Fistulas

Most fistulas require surgery, with either the placement of a seton to drain the area of infection or a fistulotomy. A seton is a small plastic loop that is inserted into the fistula to allow it to drain freely and prevent infection.

For a fistulotomy, the physician surgically opens the fistula, flushes out its contents, and stitches it open or leaves it as is to heal. Part of the surgery usually requires cutting a small section of anal control muscles. Depending on the location of the fistula, there can be a minimal risk of developing minor fecal incontinence, but our surgeons are skilled in minimizing damage to this area.