Anal fissures are divided into acute (recent) and chronic (typically lasting more than 8-12 weeks). A simple tear in the anus can be seen in acute fissures, whereas chronic fissures might include swelling and scar tissue over a longer period of time. Anal fissures are caused by a tear in the sensitive lining of the anus, with pain and bleeding as typical symptoms. Patients experience severe discomfort during, and especially after, a bowel movement. This can last anything from a few minutes to several hours.