Anal fissure can be acute or chronic.

• Acute Anal Fissure: It is a deep tear in the lower anal skin with severe sphincter spasm without oedema or inflammation.
  It presents with severe pain and constipation.
• Chronic Anal Fissure: It has got inflamed, indurated margin with scar tissue.
  Ulcer at its inferior margin is having a skin tag which is oedematous, acts like a guard—sentinel pile.
  Proximally hypertrophied anal papilla is observed.
  It can cause repeated infection—fibrosis—abscess forma-tion—fistula formation.
  Chronic fissure is less painful than acute one.
  Multiple fissures are seen in inflammatory bowel disease, homosexuals and venereal diseases.
  Chronic fissure can cause complications like—abscess, fistula formation.