An anal fissure is a narrow tear that extends from the muscles that control the anus (sphincters) up into the anal canal. These tears usually develop when anal tissue is damaged during a hard bowel movement or when higher-than-normal tension develops in the anal sphincters.

An anal fistula is a tubelike passage (tract) from the anal canal to a hole in the skin near the anus. This may occur after rectal surgery, after an abscess in the rectal area, or as a complication of a bowel disease.