Anal fissures are tears in the mucosa of the anal canal and are a very common cause of bright red blood associated with bowel movements. Fissures should be suspected if a patient complains of long-lasting pain or burning during and after defecation. Fissures can be caused by straining and passage of hard stool. Additionally, the presence of fissures and subsequent pain with defecation can lead to stool retention (particularly in children), worsening constipation, and impairing fissure healing.

Most patients have only one posterior midline anal fissure. Lateral fissures have been associated with trauma, sexually transmitted infections, and other gastrointestinal tract disorders such as inflammatory bowel disease. Multiple fissures of the anal canal can be detected after abuse or in patients with significant underlying medical problems.

Careful history and physical examination usually confirm the diagnosis. Parents may report a history of painful constipation and may have noticed red blood associated with bowel movements. It is extremely important to ask about associated fever, rash, oral or skin lesions, diarrhea, abdominal pain, and weight loss, as systemic diseases may manifest with anal lesions. The pain associated with anal fissures is an important psychological feature to evaluate and address.

Consideration of anal trauma (sexual activity or sexual abuse), inflammatory bowel disease, and chronic constipation are most important when making the diagnosis of anal fissures and addressing the underlying etiology for future prevention.