Anal fistula is the medical term for an infected tunnel that develops between the skin and the muscular opening at the end of the digestive tract (anus). Most anal fistulas are the result of an infection in an anal gland that spreads to the skin. Surgery is usually needed to treat anal fistula.

  • Diagnostic expertise. Mayo specialists use state-of-the-art imaging technology to trace the pathways of anal fistulas, including complex cases.
  • Advanced treatments. Mayo offers the latest treatment options, to avoid complications and recurrence of anal fistula.
  • Experience. About 600 people are treated for anal fistula each year at Mayo Clinic. Mayo surgeons have experience with several treatment options, so treatment can be tailored to your specific needs.

Mayo Clinic in Rochester, Minn., ranks No. 1 for digestive disorders in the U.S. News & World Report Best Hospitals rankings. Mayo Clinic in Scottsdale, Ariz., and Mayo Clinic in Jacksonville, Fla., are ranked high performing for digestive disorders by U.S. News & World Report.

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Specialists in colon and rectal surgery usually manage care for adults who have anal fistula.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Specialists in colon and rectal surgery usually manage care for adults who have anal fistula.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

Specialists in colon and rectal surgery usually manage care for children and adults who have anal fistula.

For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

Knowing the complete path of an anal fistula is important for effective treatment. The opening of the channel at the skin (external) generally appears as a red, inflamed area that may ooze pus and blood. This external opening is usually easily detected.

Finding the fistula opening in the anus (internal opening) is more complicated. Mayo specialists use the latest technology:

  • Endoscopic ultrasound uses high-frequency sound waves to produce detailed images of the sphincter muscles and other structures of the pelvic floor.
  • Fistulography is an X-ray of the fistula after a contrast solution is injected.
  • Magnetic resonance imaging may be used for fistulas that are very difficult to find.

Other options include:

  • Fistula probe, an instrument specially designed to be inserted through a fistula
  • Anoscope, a small endoscope used to view the anal canal
  • Flexible sigmoidoscopy, a procedure to rule out other disorders such as ulcerative colitis and Crohn's disease

Read more about MRI and flexible sigmoidoscopy.

Treatment of anal fistula depends on the fistula's location and complexity. The goals are to repair the anal fistula completely to prevent recurrence, and to avoid damaging the sphincter muscles, which can lead to fecal incontinence.

The options include:

Fistulotomy

The surgeon cuts the fistula's internal opening, scrapes and flushes out the infected tissue, then flattens the channel and stitches it in place. To treat a more complicated fistula, the surgeon may need to remove some of the channel. Fistulotomy may be done in two stages if a significant amount of sphincter muscle must be cut or if the entire channel can't be found.

Advancement rectal flap

The surgeon creates a flap from the rectal wall before removing the fistula's internal opening. The flap is then used to cover the repair. This procedure can reduce the amount of sphincter muscle that is cut.

Seton placement

The surgeon places a silk string (seton) into the fistula to help drain the infection.

Fibrin glue and collagen plug

The surgeon clears the channel and stitches shut the internal opening. Special glue made from a fibrous protein (fibrin) is then injected through the fistula's external opening. The anal fistula tract also can be sealed with a plug of collagen protein and then closed.

Ligation of the intersphincteric fistula tract (LIFT)

LIFT is a two-stage treatment performed at Mayo Clinic in Florida for more complex or deep fistulas. LIFT allows the surgeon to access the fistula between the sphincter muscles and avoid cutting them. A seton is first placed into the fistula tract, forcing it to widen over time. Several weeks later, the surgeon removes infected tissue and closes the internal fistula opening.

Ostomy and stoma

The surgeon creates a temporary opening in the abdomen to divert waste into a collection bag, to allow the anal area time to heal.

Muscle flap

In very complex anal fistulas, the channel may be filled with healthy muscle tissue from the thigh, labia or buttock.

Mayo Clinic scientists are working to improve the imaging and treatment of anal fistulas, with a special focus on minimally invasive treatment techniques.

Mayo publications

See a list of publications by Mayo Clinic doctors on anal fistula on PubMed, a service of the National Library of Medicine.

Nov. 22, 2010