Category Archives: Gastroenterology

The pharynx and oesophagus

STRUCTURE

The oesophagus is a muscular tube, approximately 25 em long, connecting the pharynx to the stomach. The muscle coat has two layers-an outer longitudinal layer and an inner circular layer of fibres. In the upper portion both muscle layers are striated. They gradually change to smooth muscle in the lower oesophagus, where they are continuous with the muscle layer of the stomach. The oesophagus is lined by stratified squamous epithelium, except near the gastro-oesophageal junction where columnar epithelium is found.

FUNCTION

The oesophagus is separated from the pharynx by the upper oesophageal sphincter, which is normally closed by the continuous contraction of cricopharyngeus muscle.

Oesophageal manometric patterns in normal and diseased states. lOS, lower oesophageal sphincter.

Oesophageal manometric patterns in normal and diseased states. lOS, lower oesophageal sphincter.

The lower oesophageal sphincter (LOS) consists of an area of the distal end of the oesophagus that has a high resting tone and is largely responsible for the prevention of reflux. The reduction in tone and relaxation that occurs with swallowing is under the control of nervous (vagal) and hormonal mechanisms.
During swallowing, the bolus of food is moved from the mouth to the pharynx voluntarily. Immediately, the upper sphincter relaxes and food enters the oesophagus. A primary peristaltic wave starts in the pharynx at the onset of swallowing and sweeps down the whole oesophagus . Secondary peristalsis occurs locally in response to direct stimulation (e.g. distension by the bolus) and helps to clear food residue from the oesophagus  Non-peristaltic, non-propulsive tertiary waves are frequent in the elderly. The LOS relaxes when swallowing is initiated, before the arrival of the peristaltic wave.

SYMPTOMS OF OESOPHAGEAL DISORDERS

Major oesophageal symptoms are:
• Dysphagia
• Heartburn
• Painful swallowing

Dysphagia

This is either due to a local lesion or is part of a generalized disease. Patients will complain of something sticking in their throat or chest during swallowing or immediately afterwards. It is always a serious symptom and the cause must be found. The causes are shown in ; benign and malignant oesophageal strictures are the commonest causes seen in hospital practice. Globus hystericus is the name given to apparent dysphagiathe sensation of a ‘lump in the throat’ in patients who do not have true dysphagia and can therefore swallow. It has no organic cause and the treatment is reassurance.

Heartburn

Heartburn is a common symptom of acid reflux. The pain can spread to the neck, across the chest, and can be difficult to distinguish from the pain of ischaemic heart disease. It can also occur at night when the patient lies flat or after bending or stooping. Hot drinks and alcohol often precipitate the pain.

Painful swallowing

Painful swallowing without real difficulty is a symptom of candidiasis and herpes simplex infection. Both these conditions are seen in AIDS patients. Ingestion of tablets such as emepronium and potassium (slow release) will produce local ulceration if they lodge in the gullet when swallowed lying down and without water.

SIGNS OF OESOPHAGEAL DISORDERS

There are very few signs associated with oesophageal disease, the main one being of weight loss as a consequence of dysphagia.

INVESTIGATION OF OESOPHAGEAL DISORDERS

BARIUM SWALLOWAND MEAL
OESOPHAGOSCOPY

Causes of dysphagia.

Causes of dysphagia.

MANOMETRY, which is performed by passing a fluidfilled catheter through the nose into the oesophagus. Changes in pressure are transmitted up the fluid column and recorded. These studies are useful in motility disorders.
BERNSTEIN r ss r-c alternate dilute acid and alkali is infused into the oesophagus via a nasal tube to try to reproduce or relieve oesophageal pain. A positive test suggests oesophagi tis but there are many false negatives. pH MONITORING-24-hour monitoring using a pHsensitive probe positioned in the lower oesophagus is being used increasingly for the identification of reflux episodes (pH <4). Brief episodes can, however, occur in normal subjects.
RADIOISOTOPE STUDIES with technetium sulphur colloid incorporated into food can also be used to study reflux. It is not widely used in the UK.

The salivary glands

Xerostomia

Xerostomia means dryness of the mouth. Causes include:
• Psychogenic-anxiety
• Pyrexia
• Drugs-anticholinergics, antihistamines, and tricyclic and related antidepressants
• Sjogren’s syndrome
• Diabetic ketoacidosis and dehydration The sensation of excess salivation (ptyalism) is chiefly psychogenic. It occurs before vomiting and with lesions of the mouth.

Bacterial and viral infections

These can affect any of the salivary glands, the commonest condition being acute parotitis due to the mumps virus. Acute parotitis due to an ascending infection with staphylococci or streptococci occurs in alcohol-dependent patients and in elderly patients, usually associated with dehydration and poor oral hygiene. Treatment consists of antibiotic and drainage of any abscess that is demonstrated.

Sarcoidosis

This can produce parotid gland enlargement. When combined with lacrimal gland enlargement it is known as Mikulicz syndrome. Salivary duct obstruction due to calculus Obstruction due to calculus usually involves the submandibular gland. There is painful swelling of the gland after eating. The stones can sometimes be felt in the floor of the mouth and their removal is usually followed by complete relief of symptoms.

Tumours

Salivarygland turnours are usually of a mixed type. They may involve any of the salivary glands but usually affect the parotid. The gland becomes swollen but not tender and treatment is by removal, although local recurrences occur.

Common mouth lesions

Ulceration Infective

HERPES SIMPLEX VIRUS type I, or rarely type 2, presents with fever and widespread confluent painful oral ulcers. After spontaneous resolution, the virus remains latent and recurs as herpes labialis (cold sores).
HAND, FOOT AND MOUTH DISEASE due to Coxsackie A virus produces mouth vesicles, usually in children. No treatment is required. Herpes zoster involving the fifth cranial nerve can produce unilateral vesicular lesions .

Non-infective

RECURRENT APHTHOUS ULCERATION of unknown aetiology affects approximately 20% of the population and is characterized by recurrent episodes of painful oral ulcers. There are three main clinical types:
• Minor aphthae are 2-4 mm ulcers which heal in 4-14 days without scarring
• Major aphthae are larger and take longer to heal (2- 10 weeks), sometimes with scarring
• Herpetiform ulcers in which many (10-100) tiny ulcers coalesce to form large ulcers
The term ‘herpetiform’ is purely descriptive and does not imply an infective aetiology. The ulcers are sometimes associated with gastrointestinal disease, notably Crohn’s disease, ulcerative colitis and coeliac disease. Other diseases associated with oral ulcers include Behcet’s disease, Reiter’s disease and systemic lupus erythematosus.
Deficiencies of iron, folic acid and vitamin B12have been noted in some patients, but in most no cause is found. Topical corticosteroids may lessen the duration and severity of an attack. The natural history is for the attacks to occur less frequently as the patient ages. Trauma, sharp teeth or ill-fitting dentures are common causes of all ulcers. Ulcers due to syphilis and tuberculosis are seen in developing countries and rarely in the UK.
SQUAMOUS CELL CARCINOMA. This presents as an indolent ulcer with surrounding induration mainly seen on the tongue and the floor of the mouth. Aetiological factors include tobacco and alcohol, particularly spirits. It used to affect men, mainly in the 50-70 age bracket, but now younger patients or women without obvious risk factors are seen. Biopsy should be undertaken and treatment is with surgery and radiotherapy.

Vesiculo-bullous disorders

Pemphigus, bullous pemphigoid and benign mucous membrane pemphigoid all cause oral bullae. A severe form of erythema multiforme, known as the Stevens- Johnson syndrome, also has bullae affecting the oral mucosa and conjunctiva.
Oral white patches White lesions may be transient or persistent. Transient white patches are either due to Candida infection or are very occasionally seen in systemic lupus erythematosus. Oral candidiasis in adults is seen in seriously ill or immunocompromised patients, or following therapy with broad spectrum antibiotics or inhaled steroids. Local causes include mechanical, irritative or chemical trauma from drugs, e.g. aspirin. Leucoplakia describes white patches for which no local cause can be found. It is associated with alcohol, and particularly smoking, and is regarded as a premalignant condition. A biopsy should alwaysbe undertaken, histology showing alteration in the keratinization and dysplasia of the epithelium. Treatment with isotretinoin reduces disease progression. Oral lichen planus presents as white striae.

The tongue

The tongue may be ulcerated in association with more general oral mucosal ulceration. A single ulcer may be malignant and this must be considered in any ulcer which persists for more than 3 weeks (see above). Loss of filliform papillae producing a smooth sore tongue (atrophic glossitis) can occur in patients with iron, vitamin B12or vitamin folate deficiency.A painful tongue without any evidence of abnormality is often psychological in nature, although deficiency states must be excluded.
Geographic tongue affects 10% of the population. There are discrete areas of depapillation on the dorsum of the tongue which change over a few days or even hours. Geographic tongue may be asymptomatic or the patient may complain of a sore tongue. The aetiology is unknown and there is no treatment other than reassurance.

The gums

The gum or gingiva is the tissue covering the alveolar process of the mandible and maxilla, and surrounds the necks of the teeth. Bleeding of the gums affects most of the adult population at some time and is due to gingivitis. This is an inflammatory process caused by failure to remove bacteria in the form of plaque from the toothgingival junction. Less commonly, bleeding may be associated with a general bleeding disorder. Patients with acute leukaemia, as well as immunocompromised patients often have severe gingivitis with bleeding. Acute ulcerative gingivitis (Vincent’s infection) occurs in the malnourished patient with poor dentition and in the immunosuppressed. It is characterized by ulceration and is usually restricted to the gingiva, particularly the interdental papillae. Smears of affected areas show a mixed infection of fusobacteria and spirochaetes. Treatment is with oral metronidazole, 200 mg three times daily, for 1 week with accompanying good mouth and oral hygiene. Failure to treat this condition properly may predispose to a more widespread infection, particularly in the immunosuppressed, termed cancrum oris. Ulceration of the gums may occur in association with more generalized oral ulceration as described above. Generalized gum swellingis a feature of chronic gingivitisand may be a side-effect of pregnancy, various systemic diseases and some drugs, e.g. cyclosporin, phenytoin and nifedipine.

AIDS and the mouth

Oral lesions are frequently seen in patients with AIDS. Some of these lesions, e.g. Candida, aphthous ulceration and acute ulcerative gingivitis, simply reflect immunosuppression and are not specific for AIDS. The other lesions described are more specificfor AIDS. Kaposi’s sarcoma presents as red/blue or purple patches which may be perioral or in the mouth usually on the palate at the junction of the hard and soft palate. Hairy leucoplakia is characterized by white patches which cannot be removed, usually affecting the lateral surface of the tongue. There is intense epithelial hyperplasia giving rise to a hairy appearance. Hairy leucoplakia is an indicator of a poor prognosis in these patients.

The mouth

Mastication of the food takes place in the mouth. The nfood then passes into the pharynx. Problems in the mouth are extremely common and although they may be trivial they can produce severe symptoms. Poor dental hygiene is often a factor. A bad taste in the mouth and offensive breath (halitosis), particularly if only noticed by the patient, are psychogenic symptoms. Patients with gastric outflow obstruction rarely have halitosis. Stomatitis is inflammation in the mouth from any cause, such as ill-fitting dentures. Angular stomatitis is inflammation of the corners of the mouth.

Investigation

Radiology and endoscopy are the principal investigations. These are usually preceded by routine haematology and biochemistry.

Plain X-rays

Plain X-rays of the abdomen are chiefly used in the investigation of acute abdomen (see p. 233). Areas of calcification can be seen in chronic pancreatitis. Routine abdominal X-rays are of little use in the management of most gastrointestinal disease. Barium contrast studies.

Barium swallow

The oesophagus is visualized as barium is swallowed in the upright and prone positions. Motility abnormalities as well as anatomical lesions can then be observed. Reflux of barium from the stomach into the oesophagus is demonstrated with the patient tipped head down, but minimal reflux under these conditions may well have no clinical significance.
Swallowing bread with the barium (to add bulk) is sometimes useful in a difficult case of dysphagia.

Barium contrast studies-useful facts.

Barium contrast studies-useful facts.

Barium meal

This is performed to examine the stomach and duodenum. A small amount of barium is given together with effervescent granules or tablets to produce carbon dioxide so that a double contrast between air and barium is obtained. This technique has a high accuracy rate when performed carefully. Single-contrast studies are not recommended. Small bowel follow-through This is used to examine the small bowel and ideally should be performed separately from a barium meal as a different technique is employed. Barium is swallowed and allowed to pass into the small intestine through the jejunum and into the ileum. This technique is the only way of demonstrating the gross anatomy of the small intestine. Views of the terminal ileum should be obtained with the use of a compression pad.Small bowel enema (enteroclysis) A tube is passed through the duodenum and a large volume of dilute barium is introduced. This technique is useful for visualizing suspicious areas seen on the followthrough  particularly strictures.

Barium enema

Barium and air are insufflated into the rectum via a retained catheter. A double-contrast view is then obtained of the whole colon, often with views of the terminal ileum as well. The patient must be prepared well with laxatives and wash-outs so that the colon is empty. Rectal examination and sigmoidoscopy usually precede this examination.

Gastroscopyand colonoscopy

Gastroscopyand colonoscopy

Abdominal ultrasound. computed tomography (cr) and magnetic resonance imaging (MRI) These techniques are being increasingly used for detecting thickened bowel, masses, abscesses and fistulas in, for example, Crohn’s disease or tuberculosis. CT, endoscopic ultrasound and MRI are also being used for evaluating tumour size and spread.

Endoscopy

Video endoscopes producing images of high quality are now available. This technical advance allows easy data collection.
OESOPHAGOGASTRODUODENOSCOPY (OGD) is often used as the investigation of choice for upper gastrointestinal disorders by gastroenterologists because of easy access, the possibility of interventional therapy and obtaining mucosal biopsies.
COLONOSCOPY allows good visualization of the whole colon and terminal ileum. Biopsies can be obtained and polyps removed. The success rate for reaching the terminal ileum is approximately 80% and the mortality is 1 : 100000. The major complication is perforation. Barium studies and endoscopy are frequently complementary and the technique chosen often depends on local expertise and work-load. Radiology is better than endoscopy for assessing motility disorders, extrinsic lesions and gastro-oesophageal reflux. Endoscopy is preferable in gastric ulcer disease (as biopsies can be obtained) and in the detection of oesophagitis. Colonoscopy is used in the sick immobile patient, in inflammatory bowel disease, for polyp follow-up and in the investigation of rectal bleeding. Barium enema is usually performed for the investigation of change in bowel habit.

Radionuclide imaging

Radionuclides are used to a varying degree depending on local enthusiasm and expertise. Indications are:
• To demonstrate oesophageal reflux using [99mTc]sul_ phur colloid
• To determine the rate of gastric emptying using [99mTc]-sulphur colloid
• To demonstrate a Meckel’s diverticulum using [99mTc] pertechnetate which has an affinity for gastric mucosa
• To show inflammation and an inflammatory mass in inflammatory bowel disease using IIIIn-labelied white cells
• Isotopic techniques can also be used to assess gastrointestinal loss of red cells, albumin and bile acids, and the retention of vitamin B12.

Clinical examination

A general examination is performed, with particular emphasis on the examination of all lymph nodes and noting the presence of anaemia or jaundice. Detailed examination of the gastrointestinal tract starts with the mouth and tongue before examining the abdomen. Examination of the abdomen (Acute abdomen, Liver disease,)

Inspection

The organs found in a normal abdomen are shown in  a normal CT scan.

Organs sometimes palpable (%) in thin subjects.

Organs sometimes palpable (%) in thin subjects.

CT scan of the normal abdomen at the level of the liver. 1, aorta; 2, spine; 3, top of right kidney; 4, liver; 5, gall bladder; 6, stomach; 7, pancreas; 8, spleen.

CT scan of the normal abdomen at the level of the liver.
1, aorta; 2, spine; 3, top of right kidney; 4, liver; 5, gall bladder;
6, stomach; 7, pancreas; 8, spleen.

Abdominal distension, whether due to flatus, fat, fetus, fluid or faeces, must be looked for. Lordosis may give the appearance of a distended abdomen; it is a common feature of the ‘abdominal distension’ seen in functional bowel disease.

Palpation

The abdominal organs may be felt in some normal subjects  but this is not common and such organs are usually only just palpable. Any palpable mass is carefully felt to decide which organs are involved and also to evaluate its size, shape and consistency and whether it moves with respiration. The hernial orifices should be examined if intestinal obstruction is suspected.
A succussion splash suggests gastric outlet obstruction if the patient has not drunk for 2-3 hours; the splash of fluid in the stomach can be heard with a stethoscope laid on the abdomen when the patient is moved.

Percussion

This is performed in the usual way to detect the area of dullness caused by the liver and spleen, and possibly bladder enlargement. The presence of fluid in the peritoneal cavity, i.e. ascites, is detected by shifting dullness. The percussion note changes from resonance to dullness when the patient is moved from one side to the other. It is a
good physical sign if performed carefully but 1-2 litres of fluid must be present to elicit it. A fluid ‘thrill’ can be elicited, but is not always helpful. A large ovarian cyst can sometimes produce an enlarged abdomen, but the dullness is more centrally placed than in ascites. Auscultation Auscultation is not of great value in gastrointestinal disease, apart from in the evaluation of the acute abdomen. Abdominal bruits are often present in normal subjects, but these are not clinically significant. Intestinal sounds
do not help in diagnosis.

Examination of the rectum and sigmoid

Digital examination of the rectum should be performed in most patients with gastrointestinal symptoms and in all patients with a change in bowel habit. The anus should be inspected for anal tags, external haemorrhoids, fissures or fistulas. In males, the prostate projects into the rectum anteriorly and its size and consistency should be noted. In women the cervix or uterus may be felt anteriorly.
SIGMOIDOSCOPY (Practical box 4.1). should, in hospital, be part of the routine examination in all cases of diarrhoea and in patients with lower abdominal symptoms such as a change in bowel habit or bleeding.
PROCTOSCOPY (Practical box 4.1) is performed in all patients with a history of bright red blood per rectum; the narrow sigmoidoscope does not distend the lumen and haemorrhoids can be missed.

Flexible-fibre sigmoidoscopy

The rigid sigmoidoscope allows inspection of only the lower 2G-25 ern of the bowel, but a 70 cm flexible fibreoptic sigmoidoscope allows much more bowel to be visualized. It also can be readily used in the outpatient department after minimal bowel preparation (a disposable enema). Seventy per cent of colonic neoplasms occur within the range of the flexible sigmoidoscope.

Stool examination

This .can be occasionally useful to confirm the patient’s symptoms, e.g. passing of blood or steatorrhoea. The shape and size may be helpful, e.g. rabbity stools in the irritable bowel syndrome. Stool charts for recording frequency and volume of defecation are useful in inpatients to follow the progress of diarrhoea.

Sigmoidoscopy and proctoscopy.

Sigmoidoscopy and proctoscopy.

Steatorrhoea

Steatorrhoea is the passage of pale, bulky stools that contain fat, sometimes float in the lavatory pan and are difficult to flush away. These stools float because of the increased air content. Normally people with steatorrhoea complain of diarrhoea, but occasionally they may pass only one motion per day.

Abdominal pain

Pain is stimulated mainly by the stretching of smooth muscle or organ capsules. Severe acute abdominal pain can .be due to a large number of gastrointestinal conditions, and normally presents as an emergency. An ‘acuteabdomen’ can occasionally be due to referred pain from  the chest, as in pneumonia, or to metabolic causes, such as diabetic ketoacidosis. In patients with abdominal pain the following should be ascertained:
• The site, intensity, character, duration and frequency of the pain
• The aggravating and relieving factors
• Associated symptoms, including non-gastrointestinal symptoms Localized abdominal pain with tenderness can very rarely arise from the abdominal wall itself. The cause is unknown, but may possibly be due to nerve entrapment; a local anaesthetic injection may help.

Upper abdominal pain

PIGASTRIC PAIN. This is very common, often a dull ache, but can be sharp and severe. Its relationship to food intake should be ascertained. It is a common feature of peptic ulcer disease, but it can be caused by a variety of upper gastrointestinal diseases.
RIGHT HYPOCHONDRIAL PAIN is usually from the gallbladder or biliary tract (see p. 281). Hepatic congestion, e.g. in hepatitis, and sometimes peptic ulcer can present with pain in the right hypochondrium. Chronic, often persistent, pain in the right hypochondrium is a frequent symptom in healthy females suffering from functional bowel disease. This chronic pain is not due to gallbladder disease.

Lower abdominal pain Pain in the left iliac fossa is usually colonic in origin. It is most commonly associated with functional bowel disease. In females, lower abdominal pain occurs in a number of gynaecological disorders and the differentiation from gastrointestinal disease is often difficult.
Persistent pain in the right iliac fossa over a long period is not due to chronic appendicitis.

PROCTALGIA. Proctalgia is a severe pain deep in the rectum that comes on suddenly but lasts only for a short time. It is not due to organic disease.

Abdominal distension

Abdominal distension or bloating is a common complaint often erroneously attributed to wind. In the absence of physical signs, the symptom is due to functional bowel disease.

Weight loss

This is due to anorexia (loss of appetite) and is a frequent accompaniment of all gastrointestinal disease. Anorexia is also common in systemic disease and may be seen in psychiatric disorders, particularly anorexia nervosa. Anorexia often accompanies carcinoma but it is a late symptom and not of diagnostic help. Weight loss with a normal or increased dietary intake occurs with hyperthyroidism. Malabsorption is never so severe as to cause weight loss without anorexia. Weight loss should be assessed objectively as patients often ‘think’ they have lost weight. For a discussion of appetite. Rectal bleeding Bright red blood on the toilet paper on wiping the anus is a common symptom of piles. There are many other causes.

Common symptoms

Dysphagia

Dysphagia is difficulty in swallowing

Incidence (approximate) of cancers at various sites of the gastrointestinal tract.

Incidence (approximate) of cancers at various sites of the gastrointestinal tract.

Heartburn

Heartburn is a retrosternal or epigastric burning sensation that spreads upwards to the throat.

Dyspepsia and indigestion

These are terms often used by lay people to describe any symptom, e.g. nausea, heartburn, acidity, pain or distension, that occurs as a result of eating or drinking. They may also be used to describe an inability to digest food. Careful questioning is required to elicit the exact nature of the patient’s complaint. ‘Indigestion’ is common; 80% of the general population will have had indigestion at some time.

Flatulence

Flatulence is the term used to describe excessive wind. It indicates belching, abdominal distension (see below) or the passage of flatus per rectum. Excessive belching is not usually associated with organic disease and is a common functional disorder. It is due to air swallowing (aerophagy), which many people do subconsciously. Some of the swallowed air is passed into the intestines, where most is absorbed. Intestinal bacterial breakdown of food, particularly high-fibre legumes, also produces a small amount of gas. Flatus consists of nitrogen, carbon dioxide, hydrogen and methane. On average, flatus is passed 10-20 times per day.

Hiccups

Hiccups are due to involuntary diaphragmatic contractions with closure of the glottis and are extremely common. Rarely they become continuous, when treatment with chlorpromazine 50 mg three times a day or diazepam 5 mg three times daily may be effective.

Vomiting

The vomiting centres are located in the lateral reticular formation of the medulla and are stimulated by the chemoreceptor trigger zones (CTZ) in the floor of the fourth ventricle, and also by vagal afferents from the gut. The CTZ are directly stimulated by drugs, motion sickness and metabolic causes. There are three stages:
• Nausea-a feeling of wanting to vomit often associated with autonomic effects including hypersalivation, pallor and sweating
• Retching-a strong involuntary effort to vomit
• Vomiting-the expulsion of gastric contents through the mouth Many gastrointestinal conditions are associated with vomiting, but nausea and vomiting without pain is frequently non-gastrointestinal in origin.
CHRONIC NAUSEA AND VOMITING with no other abdominal symptoms are usually due to psychological causes. Early morning vomiting is seen in pregnancy, alcohol dependence and some metabolic disorders, e.g. uraemia.

Constipation

Constipation is difficult to define in terms of frequency of bowel action because there is considerable individual and geographical variation. Patients usually consider themselves constipated if their bowels are not opened on most days. The difficult passage of hard stools is also regarded as constipation, irrespective of stool frequency. Normal daily stool weight in the UK is only 50-300 g, whereas in developing countries with a high fibre intake stool weight is 500 g or more with bowel actions two to three times per day.

Diarrhoea

Diarrhoea is extremely common; a single episode is usually due to dietary indiscretion. True diarrhoea implies the passing of increased amounts (>300 g per 24 hours) of loose stool and is different from the frequent passage of small amounts of stool, which is commonly seen in functional bowel disease. The consistency of the stools is important; watery stools of large volume are always due to an organic cause. Bloody diarrhoea usually implies colonic disease. Diarrhoea can be either acute or chronic. If it is acute, infective causes must be looked for.

Causes of vomiting.

Causes of vomiting.

Introduction

Gastrointestinal disease is a major cause of ill-health worldwide. In developing countries infection and malnutrition are common. For example, over a billion people are infested with roundworms and hookworms, and amoebiasis affects over 10% of the world’s population. Poor hygiene and malnutrition allows the spread of infective organisms and many infections could be prevented by improved sanitation and education.
In developed countries, much of the work-load is due to non-organic disorders, which are also becoming a worldwide problem. Nevertheless approximately 20% of all cancers occur in the gastrointestinal tract.