An anal fissure is a small tear which lies in skin lining on an opening of the anus. Hard and difficult bowel movements are the main cause of anal fissure which causes severe pain or bleeding. In which doctor may recommend few changes in diet for soft stools, and topical anesthetics to reduce pain. However, surgery is required and the renowned surgeon will work efficiently to relax the anal area, so that patient does not need to go through the extreme anal pain.
Anal fissures often heal within a few weeks if you take steps to keep your stool soft, such as increasing your intake of fiber and fluids. Bathing in warm water for 10 to 20 minutes several times a day, especially after bowel movements, can help relax the sphincter and promote healing.

Signs and symptoms of an anal fissure include:

  • Pain, sometimes severe, during bowel movements
  • Pain after bowel movements that can last up to several hours
  • Bright red blood on the stool or toilet paper after a bowel movement
  • Itching or irritation around the anus
  • A visible crack in the skin around the anus
  • A small lump or skin tag on the skin near the anal fissure.

The symptoms of anal fissure:

  • Anal pain
  • Rectal bleeding
  • Blood in stool
  • Bright red blood on toilet paper
  • Blood in underwear
  • Blood in diapers
  • Bleeding when passing stool
  • Pain when passing stool
  • Pain after passing stool
  • Pain for several hours after passings tool
  • Anal itching

Causes of anal fissure:

Hard stools especially associated with constipation - The increased pressure exerted in an effort to pass the hard stools causes tearing of the delicate perianal skin.
Diarrhoea - The frequent forceful bowel movement causes tearing of the anal skin.
Iatrogenic - A tear may occur during insertion of a rectal thermometer, USG probe, endoscope, enema tube.
Anal sex - Commonly encountered in homosexuals.
Rare causes - Crohns disease, leukemia, tuberculosis, sexually transmitted diseases, viral infections etc
Conservative management: At least 50% of anal fissures are healed by medical management, which includes topical ointments, sitz baths, dietary modifications (i.e. incorporating a high fibre diet and avoiding foods that are not well digested like maida, popcorn, chips), drinking plenty of fluids, and using stool softeners/ laxatives.
Surgery:  Surgery treatment required when fissures do not respond to other treatment. The two options available are:
Chemical Internal Sphincterotomy: A minimum invasive approach to relax the anal muscle by injecting chemicals into the anal sphincter muscle and partially paralyzing it. 
Lateral Internal Sphincterotomy: In this surgery, a portion of the anal sphincter muscle is divided which helps the fissure to heal and decrease the pain and spasm. If a sentinel pile is present, it is removed to promote healing. It is a quick surgical process and can also be performed as a short outpatient procedure. The chances of recurrence are almost nil. It is the most effective treatment option for non-healing fissures.