Anal fissure

What is an anal fissure?

An anal fissure is a split in the lining of the anal canal.  Patients experience pain that occurs on defecation with passage of bright red blood, seen on the toilet paper. Defecation can be so painful that patients are afraid to go to the toilet; this then leads to the passage of large, hard stools that make the problem worse.  A throbbing anal discomfort can persist for several hours after a bowel movement, caused by spasm of the anal sphincter.  Healing of the fissure is often impaired by this spasm, which causes a reduction in blood supply to the anal canal lining.

Treatment of anal fissure

Treatment is aimed at breaking the cycle of pain, spasm, and reduced blood supply.  It consists of two components: achieving a soft stool consistency and relaxation of the internal sphincter.  Medical therapy leads to healing in the vast majority of patients with acute anal fissures, and almost half of the patients with chronic fissures.

1. Achieving a soft non-irritant stool

Dietary modification to increase the amount of fibre [aim for 25g to 30g per day], or taking a fibre supplement, can help achieve a soft stool consistency.  It is also important to avoid foodstuffs that cause irritant faeces such as coffee, tea, caffeinated fizzy drinks, beer, chocolate, spicy foods, and tomatoes.  The key, though, is to ensure that the patient increases the amount of water he or she drinks to 2 litres per day in the average adult.

2. Relaxation of the internal sphincter

Warm baths may ease the acute pain in the anal area.  After a bath, the anal area should be carefully dried with a towel or a hair dryer with cool air.  If a bath is not possible, using a wet baby wipe after a bowel motion is helpful to achieve optimal cleansing of the anal skin.

Based on the theory that anal fissures fail to heal due to reduced blood supply, topical ointments that reduce the anal sphincter pressure such as diltiazem or GTN may be useful.  Injection of a muscle relaxant to the internal sphincter can be used as a second line therapy; studies show rates of healing of 60%-70% after a single injection of 15 or 20 Units of the relaxant.  Surgical treatment is generally reserved for fissures that have failed to be treated successfully with medical therapy.  Lateral sphincterotomy is the procedure of choice for the majority of surgeons.  This operation surgically divides a portion of the internal anal sphincter and is highly effective in reducing symptoms of chronic anal fissure.  However, persistent minor incontinence may occur in up to 35% of patients after the procedure; some will resolve within 6 weeks or so and some will be permanent.

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