Anal Fistula

An anal fistula is an abnormal tunnel that leads from the anal canal (which carries stool from the large intestine) to a hole in the skin near the anus (the opening through which stool passes out of your body).


Food you eat goes from your stomach into your intestine. As the food is digested, waste material (stool) forms. Stool passes through your large intestine, through the rectum and anal canal, and out of your body through the anus.

The anus has a number of tiny glands (clusters of specialized cells) that make lubricating fluid. Sometimes these glands can become infected. This type of infection may lead to the development of a pocket of pus (abscess). An anal fistula often develops after an infection or abscess; It is nearly always caused by a past anorectal abscess.

You are at a higher risk of developing an anal fistula if you have:

  • Had an anal abscess.

  • Chronic inflammatory bowel disease, such as Crohn's disease or ulcerative colitis.

  • Conditions in which there are inflamed outpouchings of the intestinal wall (diverticulitis).

  • Colon or rectal cancer.

  • Sexually transmitted diseases involving the rectum, such as gonorrhea or chlamydia.

  • A history of anal radiation treatments, injury, or surgery.

  • An HIV infection.

  • A problem that has required treatment with steroid medicines for more than a short time.


  • Anal pain, particularly around the area of a past abscess.

  • Drainage of pus, blood, stool or mucus from an opening in the skin.

  • Swelling around the skin opening.

  • Worn off skin around the opening.

  • A hot or red area near the anus.

  • Diarrhea.

  • Fever and chills.

  • Tiredness (fatigue).


  • In some cases, the opening of an anal fistula is easily seen during a physical exam.

  • A probe or scope may be used to help locate the opening of the fistula. In some cases, dye can be injected into the fistula opening, and X-rays can be taken to find the exact location and path of the fistula.

  • A sample (biopsy) of the fistula tissue or anus may be taken to check for cancer.


  • An anal fistula may need surgery to open it up and allow it to heal. This type of operation is called a fistulotomy.

  • A specialized kind of glue or plug to seal the fistula may be used.

  • An antibiotic may be prescribed to treat an existing infection.


  • Take medications (such as antibiotics) as prescribed by your caregiver.

  • Only take over-the-counter or prescription medicine for pain, discomfort, or fever as directed by your caregiver.

  • Follow your prescribed diet. You may need a higher fiber diet to help avoid constipation.

  • Drink lots of water as directed.

  • Use a stool softener or laxative, if recommended.

  • A warm sitz bath several times a day may be soothing, as well as help with healing.

  • Follow excellent hygiene to keep the anal area as clean as possible. Consider using pre-moistened towelettes to keep the anal area clean after using the bathroom.


  • You have increased pain not controlled with medications.

  • You notice new swelling, redness, or hotness in the anal area.

  • You develop any problems passing urine.

  • You develop a fever (more than 100.5° F (38.1° C).


  • You have severe, intolerable pain.

  • You have severe problems passing urine or cannot pass any urine at all.

  • You develop an unexplained oral temperature above 102.0° F (38.9° C).

  • You notice new or worsening leakage of blood, pus, mucus, or stool.