ANAL AND PERIANAL DISORDERS

Although trivial in pathological terms, these conditions are extremely distressing and embarrasing.Patients often put up with symptoms for a long time before seeking medical advice.

The common anal symptoms are:- anal bleeding due to bleeding piles, anal fissures, anal carcinoma- anal pain and discomfort due to anal fissure, complicated piles- perianal itching and irritation due to local skin irritation, low-gradefungal and bacterial infection.-“something coming down”: piles, rectal prolapse, pedunculated polyp.- perianal discharge: fistula in ano, proctitis, villous adenoma, ulcerated carcinoma of the anal canal.

Anatomy of the anal canalThe anal canal is about 4 cm. long, surrounded by the anal sphincter mechanism.Except during defecation, its lateral walls are kept in apposition by the levatores ani muscles and the anal sphincters.The upper half of the anal canal is lined by a continuation of the rectal glandular mucosa.This gives way abruptly to squamous epithelium (modified skin) at the dentate line.

The upper half of the anal canal has the following important anatomical features:- it is lined by columnar epithelium- it is thrown into vertical folds called anal columns which are joined together at their lower ends by small semilunar folds called anal valves. At the base of each valve are small anal sinuses into which open 4-8 anal glands.Some of these glands are racemose and reach the intersphincteric layer.The function of these glands is obscure and their importance lies in the fact that they may be the route of infections into the submucous and intersphincteric spaces and lead to abscess formation.The nerve supply is the same as that for the rectal mucosa and is derived from the autonomic hypogastric plexuses. It is sensitive only to stretch.The arterial supply is provided by the superior rectal artery, a branch of inferior mesenteric artery.The venous drainage is mainly by the superior rectal vein a tributary of the inferior mesenteric vein.

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The lymphatic drainage is mainly upward along the superior rectal artery and then eventually to the inferior mesenteric nodes.

The lower half of the anal canal has the following important features:- it is lined by stratified squamous epithelium which gradually merges at the anus with the perianal epidermis.- there are no anal columns- the nerve supply is from the somatic inferior rectal nerve; it is sensitive to pain, temperature, touch and pressure.The arterial supply is the inferior rectal artery a branch of the internal pudental artery. The venous drainage is by the inferior rectal vein, a tributary of the internal pudental vein which drains into the internal iliac vein.The lymph drainage is downward to the medial group of superficial inguinal nodes.

The anal sphincter mechanism has three constituents, the internal sphincter, external sphincter and puborectalis muscle.The internal sphincter represents a downward but thickened continuation of the rectal wall smooth muscles. This is the involuntary internal sphincter.The encircling external sphincter and the puborectalis sling (which is a part of levator ani) arise from the pelvic floor.The external sphincter may be divided into three parts: subcutaneous, superficial and a deep part.The puborectalis fibers cause the rectum to join the anus at an acute angle.

HemorrhoidsThey represent vascular swellings involving the internal or external venous plexuses. Hemorrhoids (piles) are extremely common, affecting nearly half of the population at some stage in their lives.Lack of fiber in the modern “civilised” diet is probably the most important etiological factor; hemorrhoids are almost unknown in underdeveloped countries.PathogenesisHemorrhoids represent excessive enlargement of the venous plexuses at the lower ends of the anal mucosa columns. Hemorrhoids are usually located in the three, seven and eleven o'clock positions. These correspond to the anatomical positions of the three most prominent anal columns.Piles are caused by straining to pass small hard stools. Increased intra-abdominal pressure inhibits venous return and the venous plexuses become distended. The bulging mucosa is then dragged distally by the hard stool. Furthermore, persistent straining at stool causes the pelvic floor to sag downwards extruding the anal mucosa and causing a minor degree of prolapse.

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Hemorrhoids are classified into first, second and third degrees according to the extent to which they prolapse through the anal canal.First degree piles never prolapse, second degree piles prolapse during defecation but then return spontaneously into the anal canal, whilst third degree piles remain outside the anal margin unless replaced digitally.

Any piles may bleed from stool trauma during defection. Large piles may thrombose if they prolapse and their venous return is obstructed by sphincter tone. Such piles then become solid and cannot be effectively replaced within the anal canal.In extreme cases the hemorrhoid undergoes venous infarction and ulceration.The local pain and irritation caused by piles results in increased anal sphincter tone and spasm thus aggravating the problem of defecation and prolapse.Long standing hemmorhoids appear to atrophy, probably by thrombosis and fibrosis leaving small skin tags at the anal margin.

The symptoms of hemorrhoids are:- perianal irritation and itching (pruritus ani)- aching discomfort and pain exacerbated by defecation- hemorrhoidal prolapse- rectal bleedingExternal piles or skin tags may be visible in the anal area.

Digital examination is essential to exclude carcinoma and provides a useful measure of anal tone. The piles are palpable as soft folds.Proctoscopy is necessary to demonstrate internal piles which are seen bulging into the lumen as the proctoscope is withdrawn.Sigmoidoscopy is essential if there is a history of bleeding or any symptoms suspicious of malignancy; occasionally a rectal polyp on a long pedicle will be diagnosed in this way.

Thrombosed or strangulated piles present with acute pain and most patients are admitted to hospital as an emergency. The diagnosis is usually obvious on inspection as an edematous, congested purplish mass is seen at the anal margin.Tight spasm of the anal sphincter makes digital examination extremely painful.Strangulated hemorrhoids are even more painful than thrombosed hemorrhoids and the strangulated mass become necrotic or even ulcerated.Conservative management and prevention of hemorrhoids1. A high fiber diet is the most important means of preventing and treating piles.2. Advise the patient to spend minimal time in defecating and to avoid straining. Some patients regularly spend a long time on the lavatory reading.3. Pruritus ani can be helped greatly if the perineum is washed and dried after defecation and kept dry by applying simple talcum powder.4. Prolapsed piles should be replaced digitally after defecation.

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5. Overuse of creams, suppositories and other topical preparations causes maceration of the perianal skin and predisposes to secondary infection.

Surgical treatment for hemorrhoids

1. InjectionFirst degree hemorrhoids (which do not regress with dietary change and avoidance of straining) and most second degree hemorrhoids are best treated by injection. An irritant solution is injected submucosally around the pedicles of the three major hemorrhoids. This provokes a fibrotic reaction, effectively obliterating the hemorrhoidal vein and causing atrophy of the piles.3-5 ml. of phenol-in-oil is injected just beneath the mucosa. Usually three injections are given near the site at which each hemorrhoidal vein leaves the hemorrhoidal plexuses at positions three, seven and eleven o’clock.Direct injection into the hemorrhoid itself is extremely painful. Injection may be repeated on two to three occasions at intervals of four to six weeks.

2. BandingAn alternative to injection is the application of Barron’s bands to obliterate the hemorrhoidal vessels.A cone of mucosa just above the hemorrhoidal neck is picked up in special forceps and drown into the banding instrument. The bands are then released around the base of the cone, constricting the hemorrhoidal vessels. The result is that the hemorrhoid slowly shrinks.

3. Hemorrhoidectomy (surgical excision)Hemorrhoidectomy is indicated for third degree hemorrhoids and for lesser degrees when other treatments have failed.Before operation, stool softeners such as bulking agents and gentle laxatives should be given to avoid postoperative constipation.The treatment of choice for thrombosed or strangulated piles is urgent hemorrhoidectomy. Prophylactic antibiotic should be given because of the greater risk of infection in necrotic tissue.Thrombosed or strangulated piles are sometimes treated conservatively with ice packs and analgesics and surgery postponed for postacute phase.

Anal fissureAn anal fissure is a longitudinal tear in the mucosa and skin of the anal canal caused by passage of a large, hard stool. The tear is nearly always in the midline of the posterior anal margin.

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The fissure causes sphincter spasm and acute pain during defecation, which persists for up to an hour. The result is a fear of defecation which aggravates the constipation.Sometimes, there is a small amount of fresh bleeding at defecation (the bleeding is slight and only noted on the toilet paper).

The history is diagnostic of an anal fissure.The fissure is concealed by the anal spasm but a small skin tag (sentinel pile) may be seen at the superficial end of the fissure.Rectal examination is extremely painful and rarely possible.Patients sometimes manage to tolerate the pain of an acute fissure by using local anaesthetic creams and then present with a chronic anal fissure.Anal sphincter spasm prevents the fissure from healing.Management of anal fissureImmediate relief can however be obtained by surgery. This involves either an anal stretch or a lateral internal sphincterotomy.The fissure heals rapidly after either procedure.Dietary advice should be given to help prevent recurrence.

Abscesses in the perianal regionAbscesses in the anal area are extremely common surgical emergencies.They present with severe pain and constant perianal pain, tenderness and swelling.Perianal abscesses begin as acute purulent infections of the anal glands. These lie between the internal and external anal sphincters and drain into tiny pits at the bases of the anal columns along the dentate line. The ducts through which they drain are very narrow and duct obstruction by feces may initiate the infection. If an abscess remains confined between the two anal sphincter layers a small intersphincteric abscess results and the only symptom may be anal pain.There is often a localised area of tenderness on rectal examination.Infection of the anal glands tends to spread laterally through the external sphincter into the tissue beneath the perianal skin, forming a perianal abscess.At this point, there is little barrier to the spread of infection into the loose fibro-fatty tissue of the ischiorectal fossa and a neglected or inadequately treated perianal abscess may develop into a much larger ischiorectal abscess.Further spread may involve the pararectal tissues above the pelvic floor resulting in a pararectal abscess.If a perianal abscess is seen early oral antibiotic treatment may abort the infection. Established abscesses require incision and drainage, which is performed under general anesthesia through the perianal skin.Large ischiorectal abscesses require packing to keep the neck of the cavity open whilst granulation tissue gradually fills the space from its depths.

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Pilonidal sinus and abscessA pilonidal sinus is a sinus tract which commonly contains hairs. It occurs under the skin between the buttocks (the natal cleft) a short distance above the anus. The sinus track goes in a vertical direction between the buttocks.A pilonadal abscess is a collection of pus in the pilonidal sinus.

Causes a pilonidal sinus

The exact cause is not clear. One theory is that the problem may develop from a minor congenital or hereditary abnormality in the skin of the natal cleft. This may explain why the condition tends to run in some families. Part of the abnormality may be that the hairs grow into the skin rather than outwards.

Another theory is that of developing skin dimples (skin pits) in the skin between the buttocks. These may develop from damaged hair follicles due to local pressure or friction. Because of local pressure, growing hair in the natal cleft may get pushed into the skin pits. Whatever the cause, once hair fragments become 'stuck' in the skin they irritate the skin and cause inflammation. Inflamed skin quickly becomes infected and so a recurring or persistent infection tends to develop in the affected area.

Certain factors increase the risk of developing the condition and include: Sedentary occupation (sitting a lot). Obesity. A previous persistent irritation or injury to the affected area. Having a hairy, deep natal cleft. A family history of the condition.

Symptoms of pilonidal sinus

A pilonidal sinus may not cause any symptoms at first. Some people notice a painless lump at first in the affected area when washing. However, in most cases, symptoms develop at some stage and can be 'acute' or 'chronic'.

Acute (rapid onset) symptomsThe patient complains of sudden increasing pain and swelling over a number of days as an infected abscess develops in and around the sinus. This can become very painful and tender.

Chronic (persistent) symptomsThe patient complains of some pain which is less intense than the 'acute' symptoms. Usually the sinus discharges some pus. This releases the pressure and so the pain tends to ease off and not become severe. However, the infection never clears completely. The symptoms of pain and discharge can persist long-term, or flare up from time to time, until the sinus is treated by an operation.

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Treatment

Acute symptomsPainkillers (such as paracetamol and/or ibuprofen) may be very helpful to improve the pain. Emergent operation to incise and drain the abscess.

Chronic (persistent) symptomsIn most cases, an operation will be advised.1. Wide excision and healing by secondary intention- this operation involves cutting out the sinus but also cutting out a wide margin of skin which surrounds the sinus. The wound is not stitched but just left to heal by normal healing processes (healing by 'secondary intention'). This usually means that the wound can take several weeks to heal and requires regular dressing until it heals. The advantage of this method is that all inflamed tissue is removed and the chance of recurrence is low. 2. Excision and primary closure. This means taking out the section of skin which contains the sinus. This is done by cutting the skin either side of the sinus, taking out the sinus, and stitching together the two sides. The advantage for this is, if successful, the wound heals quite quickly. However, the risk of a recurrence, or of developing an infection of the wound after the operation, is higher than the above procedure.

Anal fistulaAnal fistulae usually develop as a complication of perianal, ischiorectal or pararectal abscesses.The fistula tracks from the lower rectum or upper anal canal through the abscess site to the perianal skin at the point of previous drainage.The communication between abscess cavity and bowel is established by spontaneous drainage into the bowel either before surgical drainage or after incomplete surgical drainage. Thus any abscess in the anal region should be drained early and thoroughly.The patient typically complains of an intermittent discharge in the perianal region.

Patients often provide a reliable history of previous pain, swelling, and spontaneous or planned surgical drainage of an anorectal abscess.

Signs and symptoms (in order of prevalence): perianal discharge, pain, swelling, bleeding, diarrhea, skin excoriation,external opening.

Important points in the history that may suggest a complex fistula include the following::inflammatory bowel disease, diverticulitis, previous radiation therapy for prostate or rectal cancer,tuberculosis, steroid therapy, HIV infection

8.Parks classification of fistula-in-ano

Intersphincteric o Common course - Via internal sphincter to the intersphincteric

space and then to the perineum o Seventy percent of all anal fistulae

Transsphincteric o Common course - Low via internal and external sphincters into the

ischiorectal fossa and then to the perineum o Twenty-five percent of all anal fistulae

Suprasphincteric o Common course - Via intersphincteric space superiorly to above

puborectalis muscle into ischiorectal fossa and then to perineum o Five percent of all anal fistulae

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Extrasphincteric o Common course - From perianal skin through levator ani muscles to

the rectal wall completely outside sphincter mechanism o One percent of all anal fistulae

On examination, a small papilla of granulation tissue is seen on the skin within 2-3 cm. of the anal margin.This clinical picture is diagnostic of an anal fistula.

The examiner should observe the entire perineum, looking for an external opening that appears as an open sinus or elevation of granulation tissue. Spontaneous discharge via the external opening may be apparent or expressible upon digital rectal examination.

Digital rectal examination may reveal a fibrous tract or cord beneath the skin. Lateral or posterior induration suggests deep postanal or ischiorectal extension.

The examiner should determine the relationship between the anorectal ring and the position of the tract before the patient is relaxed by anesthesia. The sphincter tone and voluntary squeeze pressures should be assessed before any surgical intervention to delineate whether preoperative manometry is indicated. Anoscopy is usually required to identify the internal opening.

Most anal fistulae are simple and superficial the internal orifice beginning below puborectalis; these are known as low anal fistulae.Assessment requires examination under anesthetic. A probe is gently manipulated through the fistula to demonstrate the internal orifice.

If this is not found blue dye can be injected into the external orifice and may be seen to merge in the anal canal.If the fistula is situated entirely below the puborectalis muscle, it is laid open by cutting down onto the probe with a scalpel, transsecting the anal margin and the whole lengh of the fistula.The wound heals spontaneously by secondary intention.There is no loss of fecal continence but flatus may be less well controlled.

If the fistula lies above the puborectalis surgical treatment is difficult and highly specialised because of the need to preserve the functional integrity of puborectalis.

Anal fistulae may sometimes occur as a manifestation of Crohn’s disease.Such fistulae tend to be multiple and in the most extreme cases form a “pepper pot” perineum.

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Rectal prolapseA rectal prolapse is a hernia of the rectum through the pelvic floor.In effect, the mucosa and muscle wall intussuscept through the anal canal.In the early stages, the prolapse occurs only with defecation and retracts spontaneously.At a later stage, the rectum may prolapse when the patient merely stands up.The patient thus becomes socially isolated.In the elderly, rectal prolapse is either remarkably well tolerated or else concealed. The patient becomes accustomed to reducing the prolapse manually after defection and rarely complains about it.A high fiber diet makes little difference to the problem since the anatomical defect will never recover spontaneously.If the prolapse occurs on standing or if incontinence develops the patient will require surgical treatment.

Management of rectal prolapseThe usual surgical procedure for rectal prolapse is an abdominal operation to secure the rectum within the abdominal cavity or pelvis.Wells operation- a sheet of synthetic material is wrapped around the rectum and sutured to the sacral concavity. The material provokes an intense fibrotic response which holds the rectum in place.

Ripstein rectopexy- hitching the rectum up to the sacral promontory with a polyester fabric sling. This operation may help to improve fecal continence but a sphincter repair operation may be necessary later if incontinence is a problem.

For the elderly, where abdominal operation is contraindicated a subcutaneous circum-anal silicone rubber ring may be inserted.

This operation may fail because the ring is too tight (causing constipation) or too loose (allowing recurrent prolapse ).

Study questions

1. A 72 years old patient, known with chronic constipation, presents 24 hours history of anal fresh bleeding following defecation. How would you manage this patient?2. What is the clinical difference between piles and anal fissure?3. How could you assess the anatomy of a complex fistula-in-ano preoperatively?4. What operations can be performed in rectal prolapse in a 60 years old patient with acute myocardial infarction diagnosed 1 month back?