An anal fissure is a small split or tear in the anal mucosa that may cause painful bowel movements and bleeding. There may be blood on the outside of the stool or on the toilet tissue following a bowel movement.

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. Most fissures heal on their own and do not require treatment, aside from good diaper hygiene. However, some fissures may require medical treatment.

The incidence of anal fissures decreases rapidly with age. Fissures are much less common among school-aged children than among 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 people with Crohn's disease.

• Pain while having a bowel movement
• Blood on the surface of stool (not mixed in with stool)
• Blood on toilet tissue or wipes
• A crack in the skin that is visible when the anus is stretched slightly (the fissure is almost always in the midline)
• Constipation, often with painful bowel movements

• Inspection of the rectum
• Physical exam of the rectal mucosa