Anal fissure is a small tear in the lining of the anus. Typically the tear happens due to severe constipation when a person tries to pass hard and large stools. Streaks of blood can be seen on the stool passed or on the tissues that are used to wipe the person’s bottom. Anal fissures heal on their own in a period of six to eight weeks. If the fissure(s) doesn’t heal within that period, you need to see a good gastroenterologist or a urologist.