D2I2.
common⚑ High burden in India

Anal fistula

Anal is a abnormal communication between the anal canal and the perianal skin. An anal fistula can be described as a narrow tunnel with its internal opening in the anal canal and its external opening in the skin near the anus. Anal fistulae commonly occur in people with a history of anal abscesses. They can form when anal abscesses do not heal properly.

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Plain-language summary adapted from Wikipedia. Not medical advice.