Anal fissure: A common cause of painful defecation

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Dr. Ian Shyaka

An anal fissure is a tear in the lining of the anus, the opening where bowel movements come out. Anal fissures cause pain, especially during a bowel movement.
There is a muscle that wraps around the anus and holds it shut normally. It is called the “anal sphincter.” The sphincter gets tense once the anus has been injured. In people with anal fissures, the sphincter goes into spasms, which can lead to further injury.

An anal fissure is most often caused by having a hard, dry bowel movement. Less commonly, fissures are caused by explosive diarrhea, foreign body insertion or anal intercourse. Anal fissures can also occur in patients who have other medical conditions such as Crohn’s disease (an inflammatory disease of the intestines). As a result, part of the medical evaluation includes testing for these conditions.

Most people who have an anal fissure feel a tearing, ripping, or burning pain when they have a bowel movement. This pain can last for hours. Some people also bleed slightly when they have a bowel movement. They might see bright red blood on the toilet paper or on the surface of the bowel movement. Some people with an anal fissure also have itching or irritation around the anus.

The diagnosis of anal fissure is made by taking history of the patient for the above associated symptoms, doing a physical examination and some tests can be asked to rule out other medical conditions with similar symptoms. If one has had bleeding, a test called a “sigmoidoscopy” or a similar test called a “colonoscopy” maybe ordered by the doctor. For these tests, the doctor puts a thin tube into the anus and advances it into the colon. The tube has a camera attached to it, so the doctor can look inside the colon and check for causes of bleeding.

The goal of treatment for anal fissures is to relieve the pain and anal sphincter spasm and heal the fissure. People who have a new anal fissure may heal on their own without special treatment while those with a chronic anal fissure usually require additional therapy.

Initial treatment is aimed at eliminating constipation, softening stools and reducing anal sphincter spasm. However, some patients (60% to 90%) may not heal or develop frequent recurrences. Such patients may require surgery, which is successful more than 95 percent of the time.

Avoiding hard bowel movements will prevent over-distension of the anus, which could open a healing fissure. Increasing fiber in the diet is one of the best ways to soften and bulk the stool. Fiber is found in fruits and vegetables.

Fiber supplements are commercially available under different trade names world over. These products work by absorbing water and increasing stool bulk, which increases the frequency of bowel movement and softens stool. These fiber supplements are very safe but side effects may include gas and bloating, especially when they are first started. They may be used alone or in combination with dietary changes.

Taking a stool softener can help in relieving the constipation that can cause further insult or new fissures. These are medicines that help make bowel movements easier to pass, although not advisable to use these medications for a long time, and could be used initially when symptoms are worse.

Sitting in warm water about 2-3 times a day can help to relieve pain and relax the sphincter. This is usually referred to as saline Sitz baths.

Other medical treatments in some settings can involve injection of a low dose of botulinum toxin into the sphincter muscle to help it relax and prevent spasms and associated symptoms.

Surgery is generally reserved for people with anal fissure who have tried medical therapy for at least one to three months and have not healed. The procedure is carried out to relax the internal anal sphincter by cutting a small piece of the sphincter muscle and relieving the tightness associated with the fissure.

Dr. Ian Shyaka is a General Practitioner at Rwanda Military Hospital