Anal Fissure

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An anal fissure is a tear in the lining of the anus, the opening where feces are excreted. The tear typically extends into a circular ring of muscle called the internal anal sphincter (figure 1). The fissure is described as acute if it has been present for less than six weeks or chronic if present for more than six weeks.

Once a fissure develops, the internal anal sphincter typically goes into spasm, causing further separation of the tear, constricting blood flow to the area, impairing healing, and causing pain.

There are no reliable estimates of the frequency of anal fissures in the general population; some studies suggest that as many as one in five persons develop a fissure during their lifetime. This may be an underestimate since some people may be too embarrassed to discuss it with their healthcare provider.


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.

A visible crack in the skin around the anus.

A small lump or skin tag on the skin near the anal fissure.


Anal fissures are most commonly caused by damage to the lining of the anus or anal canal, the last part of the large intestine. Most cases occur in people who have constipation, when a particularly hard or large poo tears the lining of the anal canal. Other possible causes of anal fissures include: persistent diarrhoea.

Risk factors

Constipation with straining to pass hard stool.

Eating a low-fiber diet.

Intense diarrhea.

Recent weight loss surgery, because it leads to frequent diarrhea.

Vaginal childbirth.

Minor trauma, especially trauma caused by high-level mountain biking.

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Complications of anal fissure can include:

Failure to heal. An anal fissure that fails to heal within eight weeks is considered chronic and may need further treatment.

Recurrence. Once you've experienced an anal fissure, you are prone to having another one.

A tear that extends to surrounding muscles. An anal fissure may extend into the ring of muscle that holds your anus closed (internal anal sphincter), making it more difficult for your anal fissure to heal. An unhealed fissure can trigger a cycle of discomfort that may require medications or surgery to reduce the pain and to repair or remove the fissure.


You may be able to prevent an anal fissure by taking measures to prevent constipation or diarrhea. Eat high-fiber foods, drink fluids and exercise regularly to keep from having to strain during bowel movements.

Add fiber to your diet. Eating about 25 to 30 grams of fiber a day can help keep stools soft and improve fissure healing. ...

Drink adequate fluids. Fluids help prevent constipation.

Avoid straining during bowel movements.

Getting more fiber (through your diet or supplements), drinking more water, and using a stool softener can ease bowel movements. This can ease the pain of having a bowel movement when you have a fissure and may even prevent future fissures. Taking a sitz bath can ease symptoms.