Anal fissures can happen to just about anyone, but there are definitely factors that raise your risk. Constipation is a major one, Dr. Zutshi says. An anal fissure is a small cut or tear in the lining of the anus. The crack in the skin causes severe pain and some bright red bleeding during and after bowel movements. An anal fissure may cause one or more of the following symptoms. An anal fissure is a tear or a cut in the anoderm (Figure 1). Constipation and passage of hard stools is often the cause of an anal fissure, although diarrhea can.