Anal and Perianal Disorders

Pathogenesis of Haemorrhoids

Constipation and pregnancy are the most common triggers for development of haemorrhoids. Lack of fibre in the modern Western diet is a likely factor. Straining during constipation raises intraabdominal pressure, which obstructs venous return, causing the venous plexuses to engorge. The bulging mucosa is then dragged distally by the hard stool. Furthermore, persistent straining causes the pelvic floor to sag downwards, extruding the anal mucosa and causing a small degree of prolapse. Haemorrhoids are usually located in the 3, 7 and 11 o’clock positions when viewed with the patient in the supine lithotomy position. These correspond to the anatomical positions of the anal cushions. The venous component causes a problem only if it becomes thrombosed to form a thrombosed external venous saccule (sometimes inaccurately labelled a perianal haematoma).

In pregnancy-related haemorrhoids, venous engorgement and mucosal prolapse are probably the main mechanisms. Progesterone mediates venous dilatation, and the foetus obstructs pelvic venous return.

Classification of Haemorrhoids

Haemorrhoids (piles) are classified into first, second and third degrees according to the extent of prolapse through the anal canal. First degree (or grade I) piles never prolapse; second degree (grade II) piles prolapse during defaecation and then return spontaneously; third degree (grade III) piles remain outside the anal margin unless replaced digitally ( Fig. 30.3 ). Most haemorrhoids can be described as internal because they are covered by glandular mucosa. Large neglected haemorrhoids may extend beneath the stratified squamous epithelium so their lower part becomes covered by skin. These are correctly described as interoexternal haemorrhoids , or more commonly ‘external piles’.

Symptoms and Signs of Haemorrhoids

Haemorrhoids often produce symptoms intermittently. Attacks last from a few days to a few weeks, often with complete freedom from trouble between times. Episodes of constipation are often a precipitating factor.

Any haemorrhoid may bleed from stool trauma during defaecation. Bleeding from the arterial component of the anal cushion results in the characteristic bright red rectal bleeding. Large haemorrhoids may prolapse and then thrombose , causing acute severe pain if venous return is obstructed by sphincter tone. Longstanding haemorrhoids eventually atrophy, probably by thrombosis and fibrosis, leaving small skin tags at the anal margin.

The common chronic or intermittent symptoms of haemorrhoids are:

• Perianal irritation and itching (pruritus ani) caused by mucus leakage. Scratching exacerbates the problem.

• Rectal bleeding (fresh blood, on the paper or separate from stool).

• Mucus leakage caused by imperfect closure of the anal cushions.

• Mild incontinence of flatus also caused by imperfect closure of the anal cushions.

• Haemorrhoidal prolapse.

Most patients reaching the surgeon have tried various anaesthetic or soothing creams and suppositories, either self-administered or prescribed by the family practitioner. The usual reasons for referral are persistent symptoms or the need to exclude malignancy as a cause of bleeding.

On examination, external 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. Haemorrhoids are not palpable unless they are large since the contained blood empties with finger pressure. Proctoscopy is needed to demonstrate internal piles, which are seen bulging into the lumen as the proctoscope is withdrawn. S igmoidoscopy , rigid or ideally flexible, is important in patients over 40 years, if there is a history of bleeding or any symptoms suspicious of malignancy; occasionally a rectal polyp will be diagnosed in this way. Since haemorrhoids are so common, they can mask an unrelated diagnosis of cancer.

Acute Presentations of Haemorrhoids

Thrombosed or strangulated haemorrhoids present with acute severe pain and many patients are admitted to hospital as emergencies. These complications are common in the late stages of pregnancy and soon after delivery. The diagnosis of thrombosed haemorrhoids is usually obvious on inspection as an oedematous, congested purplish mass at the anal margin. Tight spasm of the anal sphincter makes digital rectal examination extremely painful. Strangulated haemorrhoids are even more painful, and the strangulated mass may become necrotic or even ulcerated. Symptomatic relief is provided by several days of bed rest and application of ice packs and topical anaesthetic gel; this conservative treatment may be the best that can safely be offered in late pregnancy. Some surgeons favour urgent haemorrhoidectomy for thrombosed or strangulated piles, accepting the slightly higher risk of complications in exchange for a more rapid recovery and a shorter hospital stay. Prophylactic antibiotics should be given to cover the operation because of the risk of infection in necrotic tissue.

Conservative Management and Prevention of Haemorrhoids

The most important means of preventing and treating haemorrhoids is avoiding constipation and ensuring a bulky stool. This is best achieved by taking a diet high in fibre with adequate fluid intake. The patient should be advised to always heed the call to evacuate. This appears to be associated with a reflex release of lubricating mucus, which may be absent later. Sufferers should be strongly encouraged to avoid straining and to spend minimal time defaecating. A prolonged ritual often leads to further straining at the end of defaecation, when a mild prolapse can be experienced as incomplete evacuation of faeces. In many patients, these simple measures are enough to relieve symptoms. Note that repetitive straining occasionally leads to the formation of a ‘ solitary ulcer ’ on the anterior wall of the proximal anal canal, which may be clinically indistinguishable from a malignant ulcer. With third degree haemorrhoids, symptoms can often be relieved by the patient replacing the prolapsing haemorrhoids digitally after defaecation.

Creams, suppositories and other topical preparations available with or without prescription are very widely used. Some contain local anaesthetic agents or steroids. They are useful for temporary symptomatic relief but do nothing to treat the underlying condition. Overuse may cause allergic reactions, maceration of the perianal skin and secondary infections.

Surgical Treatments for Haemorrhoids

Injection of Sclerosants or Banding

First-degree haemorrhoids, which do not regress with dietary change and avoiding straining, and most second-degree haemorrhoids, can be treated on an outpatient basis by sclerosant injections or banding.

In sclerotherapy , with the aid of a proctoscope, 1 to 3 ml of a mildly irritant solution of 5% phenol in oil is injected submucosally around the pedicles of the three major haemorrhoids in the insensitive upper anal canal. This provokes a fibrotic reaction, effectively obliterating the haemorrhoidal vessels and causing atrophy of the haemorrhoids ( Fig. 30.4 ). Injections are painless if the needle is placed correctly; direct injection into the haemorrhoid would be extremely painful. Sclerotherapy is usually repeated on two to three occasions at intervals of 4 to 6 weeks. Note: sclerotherapy is not suitable for patients with nut allergies because of the nut origin of the carrier oil, and should ideally be avoided in males because of the risk of prostatitis and impotence.

An alternative and much more commonly used treatment is banding . A cone of mucosa just above the haemorrhoidal neck is drawn into a banding instrument, often by suction, and tight elastic bands released around the base of the cone, constricting the haemorrhoidal vessels ( Fig. 30.5 ). Importantly, the bands are not placed around the stalks of prolapsing haemorrhoids; this would be unbearably painful because of the somatic innervation of anal skin. The result of banding is that the haemorrhoid gradually shrinks. The bands separate with time and are passed. Of note, both sclerotherapy and banding techniques can and may need to be repeated.