Diagnosis at Mayo ClinicBy Mayo Clinic Staff
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, including the following:
- 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.
- MRI may be used for fistulas that are very difficult to find.
Other options include:
May 06, 2015
- 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
- An injected dye solution, which may help locate the fistula opening
- Abscess and fistula expanded information. American Society of Colon and Rectal Surgeons. https://www.fascrs.org/patients/disease-condition/abscess-and-fistula-expanded-information. Accessed April 19, 2015.
- Anorectal fistula (fistula in ano). The Merck Manual Professional Edition. http://www.merckmanuals.com/professional/gastrointestinal-disorders/anorectal-disorders/anorectal-fistula. Accessed April 20, 2015.
- Cook AJ. Decision Support System. Mayo Clinic, Rochester, Minn. April 16, 2015.
- Schwartz DA, et al. The role of imaging tests in the evaluation of anal abscesses and fistulas. http://www.uptodate.com/home. Accessed April 20, 2015.
- Breen E, et al. Anorectal fistula: Clinical manifestations, diagnosis, and management principles. http://www.uptodate.com/home. Accessed April 20, 2015.
- Wolff BG (expert opinion). Mayo Clinic, Rochester, Minn. April 23, 2015.
- Pigot F. Treatment of anal fistula and abscess. Journal of Visceral Surgery. In press. Accessed April 23, 2015.