Anal fissure is a small tear in the thin, moist tissue (mucosa) that lines the anus. Anal fissure may occur when you pass hard or large stools during a bowel movement.
- Trauma to the inner lining of the anus leads to the formation of anal fissure. A hard stool causes trauma to the anal canal. However diarrhea can also cause fissure.
- The external and internal anal sphincters (muscles) underlie and support the anal canal. Patients with tight sphincter muscles are prone to develop fissure.
- Severe anal pain produces spasm of the anal sphincter resulting in decrease blood flow to the site of injury. This further impairs the healing of the fissure.