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Anal Fissure

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05/05/2006

An anal fissure is a crack or ulcer in the lining of the anus (see below). Whilst these can occur at any age it usually occurs in young adults. The majority seem to develop without any particular cause.  Fissures cause intense pain, especially after a bowel motion.  The pain lasts for acouple of hours.
 


There is usually some bleeding noticed on the toilet tissue.  Occasionally, an abscess can develop.

What is the treatment?

Approximately 50% heal either by themselves or with nonoperative treatment, including topical application of medication along with the avoidance of constipation.  The longer that a fissure has persisted over time, the less likely it will be to heal by itself. If there is no improvement over a six week period surgery may be indicated.

Occassionaly, acute fissures can heal by themselves spontaneously, with good anal hygiene consisting of a thorough cleansing after each bowel movement with thick quilted baby wipes or aqueous cream and cotton wool.  Whilst the use of sitz baths (soaking the anal area in plain warm water for 20 minutes, several times a day) may help to relieve fissure symptoms it may not actually aid the healing process. A topical hydrocortisone preparation applied to the folds of the anal verge several times a day will help to relieve symptoms and in some instances can aid the healing process.

A high fiber, well balanced diet, and encouragement of regular normal stools are important in helping to heal the fissure. If pain is severe, an anesthetic ointment can be introduced freely and frequently with the finger, utilizing finger cots.

Conservative treatment or chemical sphincterotomy


Since anal fissures are characterized by spasm of the internal anal sphincter and a reduction in mucosal blood flow, the aim of treatment is to relieve ischemia by reducing resting anal pressure and improving mucosal perfusion.  It has been shown that a local application of topical nitrates reduces anal sphincter pressure and improves anodermal blood flow. This dual effect results in fissure healing in more than 80% of patients. The principal side effect is headaches in 20%-100% of cases.

The most commonly used agent is topical 0.4% GTN (glyceryl tri-nitrate) ointment (rectogesic).  A small amount, about the size of a pea is applied within the anal canal three times a day.  Success is seen in about two thirds of patients.  10% of patients get a headache (causes the blood vessels in the brain to dilate).  If you respond to GTN you should probably continue with a second prescription.  An alternative is 0.2% Diltiazem.  This is used in exactly the same manner and doesn't cause headaches! 


It has also been shown that local a local injection of 25 units of botulinum toxin near the fissure between the internal and external sphincter on each side causes denervation, sphincter muscle weakness and reduction of resting anal sphincter pressure, which can then allow the fissure to heal.  This is usually done under a general anaesthetic.  Fissure healing occurs in more than 60% of patients. The principal side effect is incontinence of flatus and or feces, which last for up to two months in 2% to 21% of cases.  In addition it does not deal with the problem of chronic scar tissue  and "guttering".

What about surgery?

Internal lateral sphincterotomy

This is the commonest operation performed for this condition. This involves dividing/cutting the lowest cm of the internal anal sphincter (see below).  This muscle is a continuation of the smooth muscle of the rectum.  It is spasm in this muscle which causes the intense anal pain.  The spasm also increases the resting pressure within the sphincter and in doing so, interrupts the blood flow to the anal lining. 
 


Cutting this muscle rarely interferes with the ability to control bowel movements and can be performed as a day case.  Often, patients complain of some mucus seepage and irritation at the site of the fissure.  The scarring often leaves a gutter.  Sometimes, patients do not develop problems of soiling, post sphincterotomy, for many years.  Once the muscle has been divided there is little that can be done.

In women who have gone through childbirth there is a risk of their having had an occult or hidden tear of the muscles of their pelvic floor.  Injury to the internal sphincter tends to cause urgency of defecation and soiling.  If there is any chance that there may have been some pelvic floor damage it is obviously sensible not to divide a normal and useful sphincter.


V-Y endoanal advancement flap

Our approach has been to reserve lateral sphincterotomy for young men with very high anal pressures and little scarring.  In women, the elderly and gay men or cases in which there is lots of scarring or an anal stenisis has developed we offer excision of the fissure and repair utilising an endo-anal advancement flap.  The procedure is performed under a general anaesthetic as a day case. 

When surgical excision is required, the chronic fissure along with the sentinel pile, papilla, and adjacent crypts are dissected free from the underlying muscle.  Associated internal and external hemorrhoids are removed. Usually the scar tissue in the posterior anal quadrant is completely denuded. The criteria for excision of fissures are chronicity and association with other anorectal disease such as hemorrhoids, mucosal prolapse, skin tags, enlarged papillae, anal contraction, and diseased crypts.





The fissure is first excised to identify the underlying internal anal sphincter.  The V shaped graft is then mobolised.






This is a controversial approach but it works and the results are very good.  It is very rare for the flap not to heal or indeed, get infected.  Like all wounds they tend to weep and as it is in the anus, the fluid tends to smell.  A simple wash with aqueous cream and water, and a pad sorts this out.


At least 90% of patients who require surgery for this problem have no further trouble from fissures. More than 95% of patients achieve prolonged symptomatic improvement. About 5-percent of patients with fissures are "chronic fissure formers", and for a variety of reasons (i.e., chronic constipation, failure to heal without scar tissue, etc.), will continue to develop new fissures despite all the efforts of medical and surgical treatment.


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SPIRE Hospital, Bristol. 
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Contact: Claire Trenberth - 0117 9804051
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