Defaecation Health Dictionary

Haemorrhoids, or piles, are varicose (swollen) veins in the lining of the ANUS. They are very common, affecting nearly half of the UK population at some time in their lives, with men having them more often and for a longer time.

Varieties Haemorrhoids are classi?ed into ?rst-, second- and third-degree, depending on how far they prolapse through the anal canal. First-degree ones do not protrude; second-degree piles protrude during defaecation; third-degree ones are trapped outside the anal margin, although they can be pushed back. Most haemorrhoids can be described as internal, since they are covered with glandular mucosa, but some large, long-term ones develop a covering of skin. Piles are usually found at the three, seven and eleven o’clock sites when viewed with the patient on his or her back.

Causes The veins in the anus tend to become distended because they have no valves; because they form the lowest part of the PORTAL SYSTEM and are apt to become over?lled when there is the least interference with the circulation through the portal vein; and partly because the muscular arrangements for keeping the rectum closed interfere with the circulation through the haemorrhoidal veins. An absence of ?bre from western diets is probably the most important cause. The result is that people often strain to defaecate hard stools, thus raising intra-abdominal pressure which slows the rate of venous return and engorges the network of veins in the anal mucosa. Pregnancy is an important contributory factor in women developing haemorrhoids. In some people, haemorrhoids are a symptom of disease higher up in the portal system, causing interference with the circulation. They are common in heart disease, liver complaints such as cirrhosis or congestion, and any disease affecting the bowels.

Symptoms Piles cause itching, pain and often bleeding, which may occur whenever the patient defaecates or only sometimes. The piles may prolapse permanently or intermittently. The patient may complain of aching discomfort which, with the pain, may be worsened.

Treatment Prevention is important; a high-?bre diet will help in this, and is also necessary after piles have developed. Patients should not spend a long time straining on the lavatory. Itching can be lessened if the PERINEUM is properly washed, dried and powdered. Prolapsed piles can be replaced with the ?nger. Local anaesthetic and steroid ointments can help to relieve symptoms when they are relatively mild, but do not remedy the underlying disorder. If conservative measures fail, then surgery may be required. Piles may be injected, stretched or excised according to the patient’s particular circumstances.

Where haemorrhoids are secondary to another disorder, such as cancer of the rectum or colon, the underlying condition must be treated – hence the importance of medical advice if piles persist.... haemorrhoids

A condition in which a person infrequently passes hard FAECES (stools). Patients sometimes complain of straining, a feeling of incomplete evacuation of faeces, and abdominal or perianal discomfort. A healthy individual usually opens his or her bowels once daily but the frequency may vary, perhaps twice daily or once only every two or three days. Constipation is generally de?ned as fewer than three bowel openings a week. Healthy people may have occasional bouts of constipation, usually re?ecting a temporary change in diet or the result of taking drugs – for example, CODEINE – or any serious condition resulting in immobility, especially in elderly people.

Constipation is a chronic condition and must be distinguished from the potentially serious disorder, acute obstruction, which may have several causes (see under INTESTINE, DISEASES OF). There are several possible causes of constipation; those due to gastrointestinal disorders include:

Dietary: lack of ?bre; low ?uid consumption.

Structural: benign strictures (narrowing of gut); carcinoma of the COLON; DIVERTICULAR DISEASE.

Motility: poor bowel training when young; slow transit due to reduced muscle activity in the colon, occurring usually in women; IRRITABLE BOWEL SYNDROME (IBS); HIRSCHSPRUNG’S DISEASE.

•Defaecation: anorectal disease such as ?ssures, HAEMORRHOIDS and CROHN’S DISEASE; impaction of faeces. Non-gastrointestinal disorders causing constipation include:

Drugs: opiates (preparations of OPIUM), iron supplements, ANTACIDS containing aluminium, ANTICHOLINERGIC drugs.

Metabolic and endocrine: DIABETES MELLITUS, pregnancy (see PREGNANCY AND LABOUR), hypothyroidism (see under THYROID GLAND, DISEASES OF).

Neurological: cerebrovascular accidents (STROKE), MULTIPLE SCLEROSIS (MS), PARKINSONISM, lesions in the SPINAL CORD. Persistent constipation for which there is no

obvious cause merits thorough investigation, and people who experience a change in bowel habits – for example, alternating constipation and diarrhoea – should also seek expert advice.

Treatment Most people with constipation will respond to a dietary supplement of ?bre, coupled, when appropriate, with an increase in ?uid intake. If this fails to work, judicious use of LAXATIVES for, say, a month is justi?ed. Should constipation persist, investigations on the advice of a general practitioner will probably be needed; any further treatment will depend on the outcome of the investigations in which a specialist will usually be involved. Successful treatment of the cause should then return the patient’s bowel habits to normal.... constipation

Constipation due to retention of FAECES in the rectum. This retention is the outcome of irregular habits, which damp down the normal re?ex causing defaecation.... dyschezia

Faeces, or stools, consist of the remainder of the food after it has passed through the alimentary canal and been subjected to the action of the digestive juices, and after the nutritious parts have been absorbed by the intestinal mucous membrane. The stools also contain various other matters, such as pigment derived from the BILE, and large quantities of bacteria which are the main component of human stools. The stools are passed once daily by most people, but infants have several evacuations of the bowels in 24 hours and some adults may defaecate only two or three times weekly. Sudden changes in bowel habit, persistent diarrhoea or a change from the normal dark brown (caused by the bile pigment, stercobilin) to very pale or very dark stools are reasons for seeking medical advice. Blood in the stools may be due to HAEMORRHOIDS or something more serious, and anyone with such symptoms should see a doctor.

Incontinence of the bowels, or inability to retain the stools, is found in certain diseases in which the sphincter muscles – those muscles that naturally keep the bowel closed – relax. It is also a symptom of disease in, or injury to, the SPINAL CORD.

Pain on defaecation is a characteristic symptom of a FISSURE at the ANUS or of in?amed haemorrhoids, and is usually sharp. Pain of a duller character associated with the movements of the bowels may be caused by in?ammation in the other pelvic organs.

CONSTIPATION and DIARRHOEA are considered under separate headings.... faeces

A disorder of the intestinal tract that affects its motility and causes abdominal distension and irregular defaecation. Traditional, but now discarded, names have been spastic or irritable colon. The disease affects around 20 per cent of the general population but in most it is no more than a minor nuisance. The causes are not fully understood, but it is generally believed that symptoms develop in response to psychological factors, changed gastrointestinal motility, or altered visceral sensation. About 50 per cent of patients meet criteria for a psychiatric diagnosis. Anxiety, depression, neurosis, panic attacks, acute disease are among possible triggering factors. Some patients have diarrhoea, others are constipated, and some alternate between the two. Many have increased sensitivity to distension of the intestine. Dietary factors such as intolerance to dairy products and wheat are apparent in certain patients.

Common features of IBS include:

abdominal distension.

altered bowel habit.

colicky lower abdominal pain, eased by defaecation.

mucous discharge from rectum.

feelings of incomplete defaecation.

Investigations usually produce normal results. Positive diagnosis in people under 40 is usually straightforward. In older patients, however, barium ENEMA, X-rays and COLONOSCOPY should be done to exclude colorectal cancer.

Reassurance is the initial and often e?ective treatment. If this fails, treatment should be directed at the major symptoms. Several months of the antidepressant amitriptyline (see ANTIDEPRESSANT DRUGS) may bene?t patients with intractable symptoms, given at a dose lower than that used to treat depression. The majority of patients follow a relapsing/remitting course, with episodes provoked by stressful events in their daily lives. (See also INTESTINE, DISEASES OF.)... irritable bowel syndrome (ibs)

Drugs or other substances used to treat CONSTIPATION. Also called aperients or purgatives, laxatives are classi?ed according to their mode of action. The four main groups are bulk, stimulant, faecal softeners and osmotics. In addition, bowel-cleansing solutions are used before surgery, ENDOSCOPY, or radiological examination of the COLON, to ensure that the bowel is clear of solid matter. However, these are not procedures for treating constipation.

People should be aware that normal bowel habits vary greatly, from twice a day to once every two or even three days. Any change from normal frequency to irregular or infrequent defaecation may signal constipation. Furthermore, before laxatives are prescribed, it is essential to ensure that the constipation is not the result of an underlying condition producing ‘secondary’ constipation. Individuals should not use laxatives too often or indiscriminately; persistent constipation is a reason to seek medical advice.

Bulk laxatives include bran and most high-?bre foods, such as fruit, vegetables and wholemeal foods. These leave a large indigestible residue that holds water in the gut and produces a large soft stool. Isphaghula husk, methyl cellulose and stercula are helpful when bran is ine?ective. Inorganic salts such as magnesium sulphate (Epsom Salts) have a similar e?ect.

Stimulant laxatives – for example, bisacodyl, senna and docusate sodium – stimulate PERISTALSIS, although the action may be accompanied by colicky pains.

Faecal softeners (emollients) There are two groups: surface active agents such as dioctyl sodium and sulphosuccinate which retain water in the stools and are often combined with a stimulant purgative; and liquid para?n which is chemically inert and is said to act by lubrication.

Osmotic laxatives These substances act by holding ?uid in the bowel by OSMOSIS, or by altering the manner in which water is distributed in the FAECES. Magnesium salts are used to produce rapid bowel evacuation, although one of them, magnesium hydroxide, should be used only occasionally. Phosphate or sodium citrate enemas (see ENEMA) can be used for constipation, while the former is used to ensure bowel evacuation before abdominal radiological procedures, endoscopy and surgery.... laxatives

Painful but ineffectual attempts at defaecation.... tenesmus

A common anal disorder caused by an elongated ulcer or tear that extends upwards into the anal canal from the anal sphincter. A fissure may be caused by the passage of hard, dry faeces. There is usually pain during defaecation and the muscles of the anus may go into spasm. There may be a small amount of bright red blood on faeces or toilet paper.

The tear often heals naturally over a few days. Treatment of recurrent or persistent fissures is by anal dilatation and a high-fibre diet, which helps soften the faeces. Surgery to remove the fissure is occasionally necessary.... anal fissure

A tightness of the anus, sometimes referred to as anal stricture.

Anal stenosis prevents the normal passage of faeces, causing constipation and pain during defaecation.

The condition may be present from birth, or may be caused by a number of conditions in which scarring has occurred, such as anal fissure, colitis, or cancer of the anus.

Anal stenosis sometimes occurs after surgery on the anus (for example, to treat haemorrhoids).

The condition is treated by anal dilatation.... anal stenosis

The end of the alimentary tract through which faeces are expelled from the body. The orifice at the end of the anal canal is open only during defaecation; at other times it is kept closed by the muscles of the anal sphincter. (See also digestive system.)... anus

Gas, commonly known as “wind”, which is passed through the anus.

Gas is formed in the large intestine by the action of bacteria on carbohydrates and amino acids in food.

Large amounts of gas may cause abdominal discomfort (see flatulence), which may be relieved by the passage of wind or by defaecation.... flatus

A solid medical preparation, of cone or bullet shape, designed to be placed in the rectum to dissolve.

Suppositories are used to treat rectal disorders such as haemorrhoids or proctitis.

They may also be used to soften faeces and stimulate defaecation.

In addition, suppositories may be used to administer drugs into the general circulation, via blood vessels in the rectum, if vomiting is likely to prevent absorption after oral administration or if the drug would cause irritation of the stomach.... suppository

This extensive, complex and ?nely tuned network of billions of specialised cells called neurones (see NEURON(E)) is responsible for maintaining the body’s contacts with and responses to the outside world. The network also provides internal communication links – in concert with HORMONES, the body’s chemical messengers – between the body’s diverse organs and tissues, and, importantly, the BRAIN stores relevant information as memory. Each neurone has a ?lamentous process of varying length called an AXON along which passes messages in the form of electrochemically generated impulses. Axons are bundled together to form nerves (see NERVE).

The nervous system can be likened to a computer. The central processing unit – which receives, processes and stores information and initiates instructions for bodily activities – is called the central nervous system: this is made up of the brain and SPINAL CORD. The peripheral nervous system – synonymous with the cables that transmit information to and from a computer’s processing unit – has two parts: sensory and motor. The former collects information from the body’s many sense organs. These respond to touch, temperature, pain, position, smells, sounds and visual images and the information is signalled to the brain via the sensory nerves. When information has been processed centrally, the brain and spinal cord send instructions for action via motor nerves to the ‘voluntary’ muscles controlling movements and speech, to the ‘involuntary’ muscles that operate the internal organs such as the heart and intestines, and to the various glands, including the sweat glands in the skin. (Details of the 12 pairs of cranial nerves and the 31 pairs of nerves emanating from the spinal cord are given in respective texts on brain and spinal cord.)

Functional divisions of nervous system As well as the nervous system’s anatomical divisions, the system is divided functionally, into autonomic and somatic parts. The autonomic nervous system, which is split into sympathetic and parasympathetic divisions, deals with the automatic or unconscious control of internal bodily activities such as heartbeat, muscular status of blood vessels, digestion and glandular functions. The somatic system is responsible for the skeletal (voluntary) muscles (see MUSCLE) which carry out intended movements initiated by the brain – for example, the activation of limbs, tongue, vocal cords (speech), anal muscles (defaecation), urethral sphincters (urination) or vaginal muscles (childbirth). In addition, many survival responses – the most powerfully instinctive animal drives, which range from avoiding danger and pain to shivering when cold or sweating when hot – are initiated unconsciously and automatically by the nervous system using the appropriate neural pathways to achieve the particular survival reaction required.

The complex functions of the nervous system include the ability to experience emotions, such as excitement and pleasure, anxiety and frustration, and to undertake intellectual activities. For these experiences an individual can utilise many built-in neurological programmes and he or she can enhance performance through learning – a vital human function that depends on MEMORY, a three stage-process in the brain of registration, storage and recall. The various anatomical and functional divisions of the nervous system that have been unravelled as science has strived to explain how it works may seem confusing. In practical terms, the nervous system works mainly by using automatic or relex reactions (see REFLEX ACTION) to various stimuli (described above), supplemented by voluntary actions triggered by the activity of the conscious (higher) areas of the brain. Some higher functions crucial to human activity – for example, visual perception, thought, memory and speech – are complex and subtle, and the mechanisms are not yet fully understood. But all these complex activities rest on the foundation of relatively simple electrochemical transmissions of impulses through the massive network of billions of specialised cells, the neurones.... nervous system

A condition in which fragments of the endometrium are located in other parts of the body, usually in the pelvic cavity.

Endometriosis is most common in

women aged 25–40 and may cause

infertility. The cause of endometriosis is unclear. In some cases, it is thought to occur because fragments of the endometrium shed during menstruation do not leave the body but instead travel up the fallopian tubes and into the pelvic cavity, where they adhere to and grow on any pelvic organ. These displaced patches of endometrium continue to respond to hormones produced in the menstrual cycle and bleed each month. This blood cannot, however, escape and

causes the formation of cysts, which may be painful and can grow to a size as large as a grapefruit.

The symptoms of endometriosis vary greatly, with abnormal or heavy menstrual bleeding being most common. There may be severe abdominal pain and/or lower back pain during menstruation. Other possible symptoms include dyspareunia (see intercourse, painful), diarrhoea, constipation, and pain during defaecation; in rare cases, there is bleeding from the rectum. Sometimes, endometriosis causes no symptoms.

Laparoscopy confirms the diagnosis.

Drugs (including danazol, progestogen drugs, gonadorelin analogues, or the combined oral contraceptive pill) may be given to prevent menstruation.

In some cases, local ablation of the endometrial deposit, using either laser or electrocautery during laparoscopy, may be needed.

If the woman is not infertile, pregnancy often results in significant improvement of the condition.

A hysterectomy may be suggested if the woman does not want children.... endometriosis

The following are described under their separate dictionary entries: FAECES; HAEMORRHOIDS; FISTULA; DIARRHOEA; CONSTIPATION.

Imperforate anus, or absence of the anus, may occur in newly born children, and the condition is relieved by operation.

Itching at the anal opening is common and can be troublesome. It may be due to slight abrasions, to piles, to the presence of threadworms (see ENTEROBIASIS), and/or to anal sex. The anal area should be bathed once or twice a day; clothing should be loose and smooth. Local application of soothing preparations containing mild astringents (bismuth subgallate, zinc oxide and hamamelis) and CORTICOSTEROIDS may provide symptomatic relief. Proprietary preparations contain lubricants, VASOCONSTRICTORS and mild ANTISEPTICS.

Pain on defaecation is commonly caused by a small ulcer or ?ssure, or by an engorged haemorrhoid (pile). Haemorrhoids may also cause an aching pain in the rectum. (See also PROCTALGIA.)

Abscess in the cellular tissue at the side of the rectum – known from its position as an ischio-rectal abscess – is fairly common and may produce a ?stula. Treatment is by ANTIBIOTICS and, if necessary, surgery to drain the abscess.

Prolapse or protrusion of the rectum is sometimes found in children, usually between the ages of six months and two years. This is generally a temporary disorder. Straining at defaecation by adults can cause the lining of the rectum to protrude outside the anus, resulting in discomfort, discharge and bleeding. Treatment of the underlying constipation is essential as well as local symptomatic measures (see above). Haemorrhoids sometimes prolapse. If a return to normal bowel habits with the production of soft faeces fails to restore the rectum to normal, surgery to remove the haemorrhoids may be necessary. If prolapse of the rectum recurs, despite a return to normal bowel habits, surgery may be required to rectify it.

Tumours of small size situated on the skin near the opening of the bowel, and consisting of nodules, tags of skin, or cauli?ower-like excrescences, are common, and may give rise to pain, itching and watery discharges. These are easily removed if necessary. Polypi (see POLYPUS) occasionally develop within the rectum, and may give rise to no pain, although they may cause frequent discharges of blood. Like polypi elsewhere, they may often be removed by a minor operation. (See also POLYPOSIS.)

Cancer of the rectum and colon is the commonest malignancy in the gastrointestinal tract: around 17,000 people a year die from these conditions in the United Kingdom. Rectal cancer is more common in men than in women; colonic cancer is more common in women. Rectal cancer is a disease of later life, seldom affecting young people, and its appearance is generally insidious. The tumour begins commonly in the mucous membrane, its structure resembling that of the glands with which the membrane is furnished, and it quickly in?ltrates the other coats of the intestine and then invades neighbouring organs. Secondary growths in most cases occur soon in the lymphatic glands within the abdomen and in the liver. The symptoms appear gradually and consist of diarrhoea, alternating with attacks of constipation, and, later on, discharges of blood or blood-stained ?uid from the bowels, together with weight loss and weakness. A growth can be well advanced before it causes much disturbance. Treatment is surgical and usually this consists of removal of the whole of the rectum and the distal two-thirds of the sigmoid colon, and the establishment of a COLOSTOMY. Depending upon the extent of the tumour, approximately 50 per cent of the patients who have this operation are alive and well after ?ve years. In some cases in which the growth occurs in the upper part of the rectum, it is now possible to remove the growth and preserve the anus so that the patient is saved the discomfort of having a colostomy. RADIOTHERAPY and CHEMOTHERAPY may also be necessary.... rectum, diseases of