An anal fissure is usually caused by constipation and straining, resulting in a tear of the skin lining the (lower) anal canal. It is an extremely painful condition, and is usually encountered in young and middle-aged adults.

What is it?

The anal canal is surrounded by two sphincter muscles for continence.  The internal muscle is an automatic muscle, which should spontaneously relax when there is bowel motion in the rectum, the external muscle then being voluntarily contracted to control passage until it is convenient to use the toilet.  When the skin overlying the internal muscle is torn, the muscle fails to relax, evacuation thus occurring against an incompletely relaxed (internal) sphincter.  This exacerbates and perpetuates the spasm and thus the pain, creating vicious cycles of tearing, spasm, tearing and attempting to heal.  When the scar tissue builds up at the edges and apex of the fissure, there is less likelihood of successful conservative attempts at healing and the more likely surgical intervention becomes.


Conservative treatment includes warm baths, stool softeners such psyllium seed preparations and simple pain relief.  “Rectogesic” (0.2% glyceryl trinitrate cream) will heal some 40% of the fissures by improving the local blood supply, which helps to relax the anal sphincter muscles and allows the fissure to heal.  It is less effective for chronic fissures with significant scar tissue.

Lateral sphincterotomy is generally recommended after failure of conservative treatment.  It is the most commonly utilsed surgical procedure and is most effective with a one percent rate of failure to heal and  minimal risk of imperfect control of wind and bowel movement when ‘tailored’ carefully to the fissure.  It is carried out under sedation with assisted local anaesthetisia and takes just a few minutes.

Another treatment that may occasionally be suggested is Botulinum toxin (“Bo-tox”) which is injected into the anal muscles to produce a temporary degree of muscle paralysis in the vicinity of the fissure, theoretically allowing effective healing.  However, the success rate is variable, ranging from 40-80% in various reports and it often needs to be repeated several times.

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