How are anal fistulas diagnosed?


Fistulas must be carefully diagnosed to determine their exact internal location. A physician will usually use an anoscope, a small instrument used to view the anal canal. Sometimes exams will be performed in the operating room.

If the fistula is complex or in an unusual spot, your physician may also employ a contrast solution or dye, which is injected into the fistula, to display its path. An MRI or endorectal ultrasound may also be performed to visualize the exact location and structure of the fistula.

In order to rule out Crohn's disease or ulcerative colitis, your physician may perform either a colonoscopy or sigmoidoscopy. These tests consist of inserting an endoscope – a flexible, thin tube with a tiny light and camera – into the anus and guiding it through the colon. A colonoscopy allows physicians to view the entire colon or large intestine; a sigmoidoscopy is a smaller instrument and only allows viewing of the lower colon.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.