If the term is used to refer to the submucosal swellings or vascular cushions that lie in the submucosal surface of the anus, then all healthy individuals have haemorrhoids.
The three vascular cushions are not, as traditionally taught, varicosities but are complex vascular structures. They are primarily composed of a plexus of arterio-venous communications suspended in a complex network of connective tissue and smooth muscle. This allows the cushions to change in size to maintain fine continence during health. The three cushions are positioned in the left lateral, right anterior and posterior areas of the anal canal.
The junctions will form a Mercedes Benz sign rotated a quarter turn clockwise.
The anal canal itself lies at the terminal end of the large intestine and is around 4cm long. The upper border is marked by the dentate line, which marks the change from the rectal columnar epithelium to the squamous epithelium of the anus. The lower border is marked by the anal verge, which marks the line demarcating hairy skin of the perineum and the non-hairy epithelium of the anus.
In disease it is now believed that fragmentation of the connective tissue matrix occurs, which causes the vascular cushion to descend. This occurs with age, hard stools, straining and diminished venous flow during pregnancy or portal hypertension. The prolapsed cushion has impaired venous return and coupled with straining causes venous engorgement and swelling.
Erosion of the epithelium leads to inflammation and bleeding, which is mainly arteriolar, accounting for the fresh red blood classically described.
The previous theory of venous varicosities has been superseded.
Prevalence is uncertain, ranging from 4 per cent in the US to 36 per cent in the UK and probably reflects unclear labelling of many anal lesions.
The lifetime incidence is 50 per cent, with men suffering from longer exacerbations than women.
Haemorrhoids can originate from tissue above or below the dentate line, making them internal or external haemorrhoids.
They can be further subclassified by the degree of prolapse. First-degree haemorrhoids bleed but do not prolapse. Second-degree haemorrhoids prolapse but reduce spontaneously. Third-degree haemorrhoids prolapse and require manual reduction. Fourth-degree haemorrhoids prolapse and are incarcerated.
Clinically, presentation reflects the degree of prolapse and secondary problems. The haemorrhoids become symptomatic when enlarged, infected, bleeding, thrombosed or prolapsed. Bleeding is bright red, reflecting its arteriolar nature and not mixed in with stools. Thrombosis is acute and painful and lasts seven to 14 days. Continence may also be affected either due to the presence of a mucus discharge or a decrease in the physiological function of the continence mechanism.
Pruritus ani reflects dermatitis secondary to mucus and microscopic faecal matter. Haemorrhoids themselves are not generally intrinsically pruritic.
Differentials include perianal haematoma, which are covered by skin, unlike haemorrhoids. Anal fissures can also cause bright red bleeding on passage of stools.
Other differentials include anal polyps, rectal prolapse, inflammatory bowel disease and rectal carcinoma.
A full abdominal examination including a digital rectal examination will help diagnose third-degree piles and help look for other differentials.
Proctoscopy is required to diagnose first-degree and second-degree piles because these empty on digital rectal examination due to the pressure of the examining finger.
The presence of red flag symptoms (old age, darker bleeding, change in bowel habit, systemic symptoms) should alert the practitioner to possible serious pathology and referral for further investigation would be indicated.
Treatment should not be undertaken in the asymptomatic. Initial treatment and prevention is helped by increased fibre and bulk of stools. Decreased defecation time is also thought to help as prolonged sitting decreases venous flow.
Where dietary fibre cannot be increased, pharmacological agents such as isphagula husk are useful for long-term control. Increased dietary fluid is essential to prevent bulk-laxatives becoming constipatory and these are contraindicated in bowel obstruction or faecal impaction.
The various ointments for topical application may provide short-term relief but there is a lack of evidence for their efficacy. They do not alter the underlying pathological changes and continuous application can be counterproductive.
Outpatient clinic options are designed to cause local necrosis of haemorrhoids, either through banding or sclerosis.
Complications requiring admission of banding are few (2.5 per cent) but potentially serious and include urinary retention, bleeding and local sepsis. Banding is the most effective outpatient procedure (79 per cent cure).
Re-banding is required for the remaining and only 2.1 per cent fail to respond in the long run. Long-term outcomes are improved with fibre supplementation.
Sclerotherapy by the injection of phenol is an alternative but success rates are poor (28 per cent) and equivalent to dietary fibre supplementation at six months.
Surgical intervention is reserved for those who suffer with severe piles.
Less than 10 per cent of referred patients require surgery.
Haemorrhoidectomy is limited to symptomatic tissue. This minimises complications such as incontinence, postoperative pain and anal stenosis. Day surgery is possible in selected patient groups with community nursing support, but is not widely undertaken. Complications include anal stenosis or incontinence, especially in the elderly.
Other procedures include stapled haemorrhoidopexy; this is not considered as effective though less painful.
Acutely thrombosed haemorrhoids are extremely painful. Emergency enucleation of the thrombosis offers rapid pain relief. Excision of the underlying vein reduces the risk of recurrence.
If presentation is late then a conservative approach may be indicated, as spontaneous resolution occurs at 10 to 14 days, though recurrence can be as high as 50 per cent.
Dr Hashmi is a GP and part-time tutor at St George's Hospital, south London
- Haemorrhoids occur with age, hard stools, straining and diminished venous flow during pregnancy or portal hypertension.
- Haemorrhoids become symptomatic when enlarged, infected, bleeding, thrombosed or prolapsed.
- Differential diagnoses include perianal haematoma, anal fissures, anal polyps, rectal prolapse, inflammatory bowel disease and rectal carcinoma.
- Initial treatment and prevention is helped by increased fibre and bulk of stools.
- Banding is the most effective outpatient procedure, while surgical intervention is reserved for those with severe piles.
- References Nisar P J, Scholefield J H. Managing haemorrhoids. BMJ 2003; 327:
- Thornton S C. Hemorrhoids. www.emedicine.com/med/topic2821.htm