An anal fistula is when a tunnel forms from the anal canal to the skin or organs near it. If left untreated, fistulas can cause problems such as infections.
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Anal fistulas are caused by damaged tissue. They are often linked to cysts or infections of anal glands. Fistulas can also be caused by sores, ulcers, or other injuries.
Sometimes there is no known cause of an anal fistula.
Anal fistulas are more common in men. However, women also get them. They are also more common in those 30 to 50 years old. Other things that may raise the risk are:
An anal fistula may cause:
The doctor will ask about symptoms and health history. A physical exam will be done. The doctor will examine the skin around the anus. This may be enough to make the diagnosis.
Sometimes the doctor wants to do more tests, such as:
The first goal is to treat any infection or health problem that caused the fistula. This may include draining the swollen area.
A fistula is repaired with surgery. Sometimes surgery is done in stages. It depends on how severe the fistula is and where it is located.
Surgery may include:
Some procedures may affect muscles that open and close the anus. Depending on the treatment, this may make it hard to hold stool (poop) sometimes.
Medicine may be given to:
The risk of anal fistula may be lowered by:
American College of Gastroenterology
American Society of Colon and Rectal Surgeons
Canadian Association of Gastroenterology
Abscess and fistula expanded information American Society of Colon and Rectal Surgeons website. Available at: https://fascrs.org/patients/diseases-and-conditions/a-z/abscess-and-fistula-expanded-information. July 26, 2021.
Anal fistula. John Hopkins Medicine website. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/anal-fistula. Accessed July 26, 2021.
Fistula-in-ano and anorectal abscess. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/fistula-in-ano-and-anorectal-abscess. Accessed July 26, 2021.
Garg P. Anal fistula associated with anal fissure. Tech Coloproctol. 2020 Jul;24(7):785.
Last reviewed July 2021 by EBSCO Medical Review Board Dan Ostrovsky, MD