Health Library

Anal Fistula


A fistula is an abnormal tunnel between 2 bodily structures. An anal fistula occurs when a tunnel develops between the rectum or anal canal and the skin of the buttocks or other organs.

Copyright © Nucleus Medical Media, Inc.


Fistulas are caused by damage to local tissue. It is often associated with cysts or infections of anal glands. A fistula can also be caused by sores, ulcers, or other injuries. It may develop at the same time as these injuries or weeks after infections clear.

In some people, anal fistulas occur spontaneously without any specific cause.

Risk Factors

Certain conditions increase the risk of developing anal fistulas:


An anal fistula may cause:

  • Pain:
    • Increases with bowel movements
    • More likely with infection
  • Persistent drainage of pus or blood through the opening in the anal skin
  • Swelling, soreness, or itching around the anal skin
  • Fever or chills
  • Fatigue
  • Feeling tired and sick
  • Discomfort


You will be asked about your symptoms and medical history. A physical exam will be done. Generally, a diagnosis can be made by examining the skin around the anus for any abnormalities.

To learn more details your doctor may suggest:

  • Anoscopy—examination of the anal canal with a scope
  • Probe—a thin, small probe may be inserted into the anal skin to see if a channel is present and where it leads
  • CT scan


If your fistula is caused by an infection or chronic health condition, it may need to be managed before the fistula is repaired. Talk with your doctor about the best treatment plan for you.

A fistula is only cured with surgical repair. Left untreated, some fistulas can cause repeat abscesses or infections. Depending on the severity or location of the fistula, surgery may be straightforward or may need to be done in stages.

Surgical procedures include:

  • Fistulotomy—A trench is created in the fistula, which allows for healing from the inside out.
  • Sealant or plug—A substance is used to fill in the fistula. Both ends of the fistula are closed off, allowing it to heal.
  • Endorectal flap—A flap is created to expose the internal opening of the fistula. The fistula is stitched shut, and then the flap is put back into place.
  • Ligation of intersphincteric fistula tract (LIFT)—The internal part of the fistula is identified and tied off. Any infected glandular tissue in the anal canal is removed and the fistula is stitched at the external opening.
  • Fistulectomy—Rarely done, the fistula is completely removed.

Some procedures may affect muscles that open and close the anus. Depending on your treatment, you may have some degree of fecal incontinence.

Medication may help manage pain and treat any infection. Stool softeners, fiber, or bulk laxatives may also be recommended to decrease strain during bowel movements.


To help reduce your chances of an anal fistula, be sure to manage any health conditions that increase your risk of infections.


American College of Gastroenterology

American Society of Colon and Rectal Surgeons

Canadian Resources

Canadian Association of Gastroenterology

Health Canada


Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rect Surg. 2011;24(1):14-21.

Abscess and fistula expanded information American Society of Colon and Rectal Surgeons website. Available at: January 9, 2018.

Anal fistula. John Hopkins Medicine website. Available at:,173. Accessed January 9, 2018.

Fistula-in-ano and anorectal abscess. EBSCO DynaMed Plus website. Available at: . Updated October 11, 2017. Accessed January 9, 2018.

Rojanasakul A. LIFT procedure: a simplified technique for fistula-in-ano. Tech Coloproctol. 2009;13(3):237-240.

van Onkelen RS, Gosselink MP. Is it possible to improve the outcome of transanal advancement flap repair for high transsphincteric fistulas by additional ligation of the intersphincteric fistula tract? Dis Colon Rectum. 2012;55(2):163-166.