Anal Fistula

The anal canal is the end portion of the intestinal tract. It includes the rectum and anus. Sometimes, an abnormal passage forms from the anal canal to the skin near the anus. This is called an anal fistula. Anal fistulas can also form from the anal canal to other organs, such as the vagina or urinary tract.

An anal fistula most often occurs from an anal gland that has developed a pus-filled infection (abscess). A fistula can also occur with certain conditions, such as Crohn’s disease or after radiation therapy for cancer. Injury to the anal canal and surgery can also lead to anal fistulas.

Symptoms of an anal fistula can include:

  • Pain in or near the rectum

  • Drainage, which may contain blood, pus, or both (the drainage may be constant or stop and start again)

  • Bleeding from the rectum

  • Urinary problems

If you have an anal abscess or infection along with a fistula, you may also notice redness, swelling, or soreness in or near the anus or rectum. You may have a fever as well. The abscess usually needs to be drained.

If caused by Crohn’s disease, an anal fistula may respond to medicines such as antibiotics and immunosuppressants. This may lead to complete closure of the fistula. But once treatment stops, there is a high chance that the fistula may form again.

Anal fistulas often require surgery if other treatments don’t correct the problem. The type of surgery depends on the type of fistula and the cause of the fistula. More than one surgery may be required.

Please discuss all forms of treatment with your healthcare provider.

Home care

As you recover from treatment, make sure to take any prescribed medicines as directed. Don't take any over-the-counter medicines without first talking to your healthcare provider.

You may also be advised to:

  • Soak in a warm bath 3 or 4 times a day.

  • Wear a pad over your anal area as directed.

  • Eat a diet high in fiber.

  • Drink plenty of fluids.

  • Use a stool softener or bulk laxative as needed.

  • Return to your normal routine only after your healthcare provider says it's OK.

Follow-up care

Follow up with your healthcare provider, or as advised.

When to seek medical advice

Call your healthcare provider right away if any of these occur:

  • Fever of 100.4°F (38°C) or higher, or as directed by your healthcare provider

  • Hard or painful stools or trouble controlling your bowel movements

  • Symptoms of the anal fistula return, like pain or drainage

  • Increased pain, redness, swelling, or drainage in or near the anus or rectum

  • Mucus, pus, or blood in the stool (dark or bright red)

  • Pain in the belly that does not respond to treatment or that does not go away after a few hours

  • Swelling in the belly that does not go away after a few hours

  • Vomiting that won’t stop


The resources below can help you learn more about anal fistulas. They may also help you find support if you have conditions such as Crohn’s disease.

  • American Society of Colon and Rectal Surgeons,

  • Crohn’s and Colitis Foundation of America,

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