Introduction

Anal and perianal disorders make up about 20% of general surgical outpatient referrals. These conditions can be distressing or embarrassing and patients often tolerate symptoms for a long time before seeking medical advice. The common anal symptoms are summarised in Box 30.1 and interpretation is discussed in Chapter 18.

The range of anal and perianal disorders is illustrated in Figure 30.1. Haemorrhoids and other common benign conditions must be distinguished from rectal carcinoma and the rare anal carcinoma. Most anal and perianal conditions can be treated on an outpatient basis, although abscesses, and haemorrhoids that have become strangulated or thrombosed may present as surgical emergencies.

• The lowest or distal zone lies between the squamous–mucocutaneous junction and the level of the anal valves at the dentate (pectinate) line. This is lined by non-keratinising squamous epithelium without skin appendages or glands; the epithelium contains some melanocytes. This area is exquisitely sensitive, for example to injection

• The anal transitional zone (ATZ). This lies between the zone of squamous epithelium below and the columnar mucosal zone above, and extends a distance varying between 0.3 and 2 cm. It consists of transitional epithelium resembling urothelium, 4–9 cell layers thick. Anal glands are present in the submucosa but there is minimal mucin production. A unique type of anal carcinoma develops from it with a viral aetiology

• The upper part of the anal canal is lined by rectal mucosa. On proctoscopic inspection, it is a dark reddish-blue where it overlies the submucosal venous plexus, becoming the typical pink of colorectal mucosa more proximally. This area of mucosa is relatively insensitive

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 intra-abdominal 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 fetus 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 ‘intero-external’ 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:

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. Sigmoidoscopy, 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. 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