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

Anal fissures are extremely common in young infants but may occur at any age. Studies suggest 80% of infants will have had an anal fissure by the end of the first year. The rate of anal fissures decreases rapidly with age. Fissures are much less common among school-aged children than infants.

In adults, fissures may be caused by constipation, the passing of large, hard stools, or by prolonged diarrhea. In older adults, anal fissures may be caused by decreased blood flow to the area.

Anal fissures are also common in women after childbirth and 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) following a bowel movement.

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 a sample of the rectal (anal) tissue.

Most fissures heal on their own and do not require treatment, aside from good diaper hygiene in babies.

However, some fissures may require treatment. The following home care methods usually heal most anal fissures.

• Cleansing more gently
• Diet changes -- eating more bulk, substances that absorb water while in the intestinal tract
• Muscle relaxants applied to the skin
• Numbing cream, if pain interferes with normal bowel movement
• Petroleum jelly applied to the area
• Sitz bath
• Stool softeners

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

• Botox injections into muscle in the anus (anal sphincter)
• Minor surgery to relax the anal muscle

Anal fissures generally heal quickly without further problems. However, people who develop fissures are more likely to have them in the future.

Occasionally, a fissure becomes chronic and will not heal. Chronic fissures may require minor surgery to relax the sphincter.

Call your health care provider if symptoms associated with anal fissure are present, or if the fissure does not heal appropriately with treatment.

To prevent anal fissures in infants, be sure to change diapers frequently.

To prevent fissures at any age:

• Keep the anal area dry
• Wipe with soft materials or a moistened cloth or cotton pad
• Promptly treat any constipation or diarrhea
• Avoid irritating the rectum

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