An anal fissure is a cut or tear in the lining of the anus. The anus is the opening through which stool leaves the body. Tears generally occur just inside the opening.
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The exact cause of an anal fissure is unknown. In most cases, tearing is the result of trauma to the anal lining. Trauma can be caused by:
- A large, dry, or hard stool
- Frequent diarrhea
- Tightened anal sphincter, a group of muscles that open and close the anus
- Anal irritation
Factors that may increase your chances an anal fissure:
- Straining to pass a bowel movement
- Prior anal surgery, which can cause scarring and decrease the tissue's elasticity
- Chronic diarrhea
- Anoreceptive intercourse
- Crohn disease or ulcerative colitis
An anal fissure may cause:
- Pain during and after a bowel movement
- Burning sensation during a bowel movement
- Bleeding with bowel movements that result in bright red blood either on the toilet tissue or in the bowl
- Small amounts of mucous may be present
Apprehension about bowel movement pain may cause you to delay bowel movements. This can make the symptom worse.
The doctor will ask about your symptoms and medical history. A physical exam will be done. Anal fissures are generally visible, so diagnosis can be made with an anal exam. If it is not visible, but suspected, your doctor may need to do other tests as long as it is not too painful. These tests include:
- Digital rectal exam—to feel for any lumps or abnormalities
- Anoscopy—examination of the anal canal with a scope
- MRI scan or CT scan if:
Fissures usually occur in predictable locations around the anus. If there are multiple cuts, or a cut in an unusual location, the doctor may order additional tests to look for other conditions.
Treatment aims to heal the cut and prevent future anal problems. Most fissures heal on their own or with self-care. Fissures that are fairly new are easier to heal than ones that have persisted for longer than 3 months.
Fissures may heal by changing some of your daily habits. These include:
- Warm sitz baths, especially after bowel movements, to help relieve pain and promote healing
- Increasing dietary fiber intake
- Increasing fluid intake
- Using stool softeners or bulk laxatives
Your doctor may prescribe:
- Topical medications to reduce pain and inflammation
- Topical nitrates and calcium channel blockers to increase blood flow to the anus and promote healing
- Injected botulinum toxin to relax tightened anal sphincter muscles
Surgery may be necessary for:
- Fissures that do not heal with other treatment methods
- Scar tissue or spasms in the anal sphincter muscles that may also delay healing
- Recurrent fissures
Surgical procedures include:
- Lateral internal sphincterotomy —A tiny incision is made in the sphincter muscle fibers to prevent spasms that result in straining during a bowel movement.
- Fissurectomy—Excision of the fissure.
- Anal advancement flap—Covering the fissure with tissue from another part of the body.
- Anal dilation—Rare procedure that widens and stretches the anal canal.
To help reduce your chances of an anal fissure:
- Drink plenty of fluids throughout the day
- Exercise regularly
- Eat foods high in fiber , such as fruits, vegetables, legumes, and whole grains
- Avoid straining during bowel movements
- Follow your treatment plan if you have Crohn disease or ulcerative colitis