An anal fissure is a small split or tear in the thin moist tissue (mucosa) lining the lower rectum (anus).

Anal fissures are very common in young infants, but may occur at any age. The rate of anal fissures drops with age. Fissures are much less common among school-aged children than infants.

In adults, fissures may be caused by passing large, hard stools, or by having diarrhea for a long time. Other factors may include: 

• Decreased blood flow to the area in older adults
• Too much tension in the sphincter muscles that control the anus

Anal fissures are also common in women after childbirth and in persons with Crohn's disease.

Anal fissures may cause painful bowel movements and bleeding. There may be blood on the outside of the stool or on the toilet tissue (or baby wipes) after a bowel movement.

Symptoms may begin suddenly or develop slowly over time.

Other symptoms may include:

• A crack in the skin that can be seen when the area is stretched slightly (the fissure is almost always in the middle)
• Constipation

The health care provider will perform a rectal exam and look at the rectal (anal) tissue.

Most fissures heal on their own and do not need treatment.

To prevent or treat anal fissures in infants, be sure to change diapers often and clean the area gently.

CHILDREN AND ADULTS

Worrying about pain during a bowel movement may cause a person to avoid them. But not having bowel movements will only cause the stools to become even harder, which can make anal fissure worse.

Prevent hard stools and constipation by:

• Making diet changes -- eating more fiber or bulk, such as fruits, vegetables, and grains 
• Increasing fluids
• Using stool softeners

Applying the following ointments or creams to the area may soothe the skin:

• Numbing cream, if pain interferes with normal bowel movements
• Petroleum jelly
• Zinc oxide, 1% hydrocortisone cream, Preparation H, and other products

A sitz bath is a warm water bath used for healing or cleansing. You should sit in the bath two to three times a day. The water should cover only your hips and buttocks.

If the anal fissues do not go away with home care methods, treatment may involve:

• Botox injections into the muscle in the anus (anal sphincter)
• Minor surgery to relax the anal muscle
• Prescription creams applied over the fissure to help relax the muscles

Anal fissures usually heal quickly without any more problems. Rarely, a fissure may not heal.

People who develop fissures are more likely to have them in the future.

Danakas G. Anal fissure. In: Ferri FF, ed. Ferri's Clinical Advisor 2008: Instant Diagnosis and Treatment. 1st ed. Philadelphia, Pa: Mosby; 2008.

Marcello PW. Diseases of the anorectum. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 125.