An anal fissure is an acute longitudinal tear or a chronic ovoid ulcer in the squamous epithelium of the anal canal. It causes severe pain, sometimes with bleeding, particularly with defecation. Diagnosis is by inspection.
Healing is aided by use of protective zinc oxide ointments or bland suppositories (eg, glycerine) that lubricate the lower rectum and soften stool. Topical anaesthetics (eg, benzocaine, lidocaine) and warm (not hot) sitz baths for 10 or 15 minutes after each bowel movement and as needed give temporary relief.