Or anal (photos)

An anal fissure is a tear in the skin of the anal canal or perianal area.

An anal fissure is a tear in the skin of the anal canal or perianal area which most commonly occurs in the posterior midline.

The majority of anal fissures are caused by local trauma to the anal canal, such as passage of hard stool or anal sex.

Anal fissures are often superficial, however with deep anal fissures, the exposed internal sphincter goes into spasm causing severe pain and leading to delayed healing. Subsequent bowel motions cause further pain and bleeding.

Look initially at the posterior midline. A chronic fissure has raised edges exposing the white, horizontally oriented fibres of the internal anal sphincter at its base.