Anal fistula

An anorectal fistula (fistula in the anus) is an abnormal path from the anus or rectum to the skin near the anus, although it can occasionally go to another organ, such as the vagina. In general, fistulas begin in a gland deep in the wall of the rectum or anus. Sometimes fistulas are the result of drainage from an anorectal abscess, but often the cause cannot be identified.

This condition is more common in carriers of Crohn's disease or in people with tuberculosis. They can also occur in people with diverticulitis, cancer, or anal or rectal injury. A fistula in an infant is usually due to a birth defect and is more common in boys than girls. Fistulas connecting the rectum and vagina may be due to a complication of radiation therapy, cancer, Crohn's disease, or an injury to the mother during delivery.