What is an anal fissure?
An anal fissure is a tear or split in the lining of the anal canal and is typically extremely painful. Tearing pain occurs on defecation with passage of bright red blood, seen on the toilet paper. Patients may also complain of a throbbing anal discomfort for several hours after a bowel movement. 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! Spasm in the anal sphincter muscle can also cause an increase in resting pressure in the anal canal which can cause reduction in blood supply in the anal canal lining and further contributes to poor healing of the fissure. An unhealed anal fissure may develop chronic ulceration in the anal canal with exposure of the internal anal sphincter at the base of the ulcer.
Treatment of anal fissure
Medical therapy leads to healing in the vast majority of patients with acute anal fissures, and almost half of the patients with chronic fissures. Treatment is aimed at breaking the cycle of pain, spasm, and reduced blood supply thought responsible for the development of the fissure. Initial treatment consists of two components: achieving a soft stool consistency and relaxation of the internal sphincter.
Achieving a soft comfortable, non-irritant stool
This can be accomplished by adjusting the diet to increase the amount of daily fibre [aim for 25g to 30g per day] or by adding a fibre supplement and avoiding foodstuffs that cause irritant faeces such as coffee, tea, caffeinated fizzy drinks, beer, chocolate, 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].
Relaxation of the internal sphincter
Warm baths may ease the acute pain in the anal area. 10-15 minutes in a warm bath can be very soothing after a bowel movement. 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 are caused by reduced blood supply, topical ointments that reduce the anal sphincter pressure such as diltiazem 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 sucessfully with medical therapy. Lateral internal 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.