An anal fissure is a tear or small cut in the lining of the anus. It occurs when large or hard stool is passed during a bowel movement. The crack in skin causes pain, and sometimes, bleeding. In most cases, the tear gets healed on its own within four to six weeks.

You may understand the occurrence of the anal fissure from the following symptoms: pain during bowel movements that may sometimes be severe; pain that lasts for hours, after bowel movements; bright red blood in stool after a bowel movement; visible crack in the skin around the anus; and burning or itching sensation in the anal area.

Passing hard or large stool often causes an anal fissure. Chronic constipation or frequent diarrhea may also cause tearing of the skin around the anus. Other common causes are straining during childbirth and anal intercourse. Crohn's disease or other inflammatory bowel diseases, syphilis, tuberculosis, HIV or anal cancer are some of the other causes which are less common.

Frequent constipation, reduced blood flow in the anorectal area, straining during childbirth, inflammatory bowel disease, and passing hard and large stool are the common risk factors. Moreover, having anal intercourse also increases the risk of anal fissure.

Doctors, by asking the patient's medical history, and by performing a physical exam, will be able to diagnose anal fissure. The tear is often visible and it shows in the inspection of the anal area. In addition to this, a rectal exam that involves inserting an anoscope into the rectum can facilitate seeing the tear easily.