Gastrointestinal system

Published on 03/03/2015 by admin

Filed under Internal Medicine

Last modified 03/03/2015

Print this page

This article have been viewed 6168 times

12 Gastrointestinal system

Michael Glynn

Introduction

The human gastrointestinal (GI) tract is a complex system of serially connected organs approximately 8 m in length, extending from the mouth to the anus, which, together with its connected secretory glands, controls the passage, processing, absorption and elimination of food. Symptoms of GI disorders are often non-specific, and signs of abnormality few unless the disease is advanced. The liver, biliary system and pancreas are embryologically part of the GI tract. Symptoms of disease in these organs can also be non-specific but each can give specific clinical features. Finally, from the standpoint of systematic history taking and examination, the kidneys, groins and genitalia are considered in this chapter.

Symptoms of gastrointestinal disease

In normal health there is some awareness of the functioning of the gut, and this can be partly related to the body’s needs. For example, thirst and hunger are common symptoms and the latter may be associated with epigastric discomfort. A dry mouth can suggest the need to drink. Swallowing is normally perceived, and there is temperature sensation in the upper and mid-oesophagus, as well as in the mouth. Vigorous peristaltic contractions in the gut, the movement of gas and fluid in the gut, called borborygmi, and the experience of a sensation of fullness in the colon and rectum prior to defaecation, or during constipation and the call to stool, are all aspects of the normal sensation of gut activity.

It is always sensible to remember that, although it is often convenient for doctors to classify symptoms according to their anatomical site of origin, patients present with single or groups of symptoms that characterize functional or disease processes. Therefore, history taking that follows these likely processes is more likely to lead to a meaningful diagnosis, particularly in the GI tract and abdomen for which many symptoms are not easily referrable to a clear anatomical site.

The common symptoms of GI and abdominal disease are listed in Box 12.1 and are discussed individually below.

Abdominal pain

Abdominal pain is a common symptom which often accompanies serious diagnoses but frequently has no definable cause. As with any pain, it is important to characterize its site, intensity, character, areas of radiation, duration and frequency, together with aggravating and relieving factors and associated features. The particular clinical problem of acute abdmominal pain is discussed on page 237-238. The particular characteristics of pain from certain frequent and important causes are given in Box 12.2. Pain that comes in waves is described as being colicky. These waves are more frequent in pain from the gut, but vary over a longer time period when pain is from the biliary or renal tract. Abdominal pain may be due to causes that are not specifically in the abdomen such as metabolic disorders (porphyria or lead poisoning) or depression.

Box 12.2 Particular characteristics of pain from frequent and important causes (the regions of the abdomen are shown in Fig. 12.5 – the loin is lateral and posterior to the lumbar area)

Peptic ulcer: epigastric, burning or gnawing, radiates through to back, meal related, wakes the patient, relieved by antacid

Gastric cancer: epigastric, severe, partly meal related, not relieved by antacid

Pancreatic: high epigastric, severe, felt front-to-back, immediately after eating, relieved by sitting forward

Midgut: periumbilical, colicky, some relation to meals

Lower gut: periumbilical or suprapubic, colicky, some relief from bowel action

Biliary: right upper quadrant, severe, colicky (but over a long time period), radiates to right shoulder, accompanied by nausea

Renal colic: loin-to-groin, colicky, very severe, accompanied by nausea

Functional: anywhere in the abdomen, colicky, accompanied by bloating, relieved by bowel action

Abdominal distension

Abdominal distension has many causes, which include flatus, fluid (e.g. ascites or ovarian cyst) and pregnancy. Marked enlargement of the major organs is sometimes noted by the patient as is the presence of a large mass lesion.

Weight loss

Weight loss may be due to lack of food intake (anorexia, dysphagia or vomiting), malabsorption of nutrients or a systemic effect of important diseases such as cancer (within or outside the GI tract), inflammatory bowel disease or chronic infections such as tuberculosis (within or outside the GI tract).

Haematemesis

Haematemesis results from bleeding in the upper GI tract (above the duodenojejunal flexure), causing the vomiting of blood. Blood that lies in gastric juice for a while turns black and may be vomited looking like ground coffee. Observed reports of vomiting blood by the patient or bystander may be unreliable, and can be confused with haemoptysis (coughing up blood).

Rectal bleeding

If bright red, separate from the stool or just on the toilet paper, this usually indicates a source in the sigmoid colon, rectum or anal canal, haemorrhoids being the commonest cause. If darker red and mixed with the stool, this usually indicates a source above the rectum, of which carcinoma is the most important cause. Large-volume rectal bleeding in an ill patient can have an upper GI source.

Melaena

Melaena describes altered blood that has passed through a significant length of the small bowel and looks jet-black, tarry and with a characteristic smell. It should indicate bleeding above the ileocaecal valve but occasionally may originate in the right colon.

Jaundice

Jaundice implies disease of the liver or the biliary tract although it may also occur from excessive haemolysis. It causes yellowness of the skin and conjunctiva, and may be associated with other cutaneous and systemic features of liver disease, often with dark urine (see below).

Nutritional assessment

The simplest nutritional assessment is to ask about weight loss and what the patient’s weight was before the illness. Patients at risk of weight loss and malnutrition may have GI disease preventing eating, reducing appetite or preventing absorption of nutrients, or non-GI disease causing reduced appetite (especially malignancy). Increased energy consumption is also important in some cancer patients and those with severe sepsis, thyrotoxicosis or burns.

A full dietary history is best undertaken by a dietitian, but a full medical clerking in a patient who has lost weight needs to include a simple assessment of the quantity and variety of foods eaten, as well as any restrictions on eating (e.g. poor dentition, social and financial circumstance), or special diets followed for medical reasons (e.g. a gluten-free diet in coeliac disease).

A full examination will include most signs of general and nutrient-specific malnutrition. Some detail of the latter is given in Table 12.1. Body weight is a key part of general examination as is height. These two can be related together and to a standard range by calculating the body mass index (BMI or Quetelet index). This is defined by the body weight (in kilograms), divided by the height (in metres) squared. The World Health Organization (WHO) classification of this index is given in Table 12.2. In the UK, the range 20-25 is often regarded as desirable, but the lower level of 18.5 is more applicable internationally. Patients with an index of more than 30 should undergo weight loss. In malnourished children, retardation of height lags behind that of weight and the relation between weight and height should always be compared with age using appropriate charts.

Table 12.1 Principal symptoms and signs due to vitamin and mineral deficiencies

Nutrients	Deficiency syndrome	Principal symptoms/signs
Vitamin A, retinol (carotenoids)		Night blindness, keratomalacia
Vitamin B₁, thiamine	Wernicke/Korsakoff, beriberi	Nystagmus, sixth cranial nerve palsy, ataxia, acidosis, dementia, paraesthesiae, neuropathy and cardiac failure
Vitamin B₂, riboflavin	Ariboflavinosis	Angular stomatitis, glossitis, magenta tongue
Niacin, nicotinic acid	Pellagra	Dermatitis of sun-exposed areas, dementia, poor appetite, difficulty sleeping, confusion, sore mouth
Vitamin B₆, pyridoxine		Poor appetite, lassitude, oxaluria
Pantothenic acid		Nausea, abdominal pain, paraesthesiae, burning feet
Biotin		Dermatitis, depression, lassitude, muscle pains, electrocardiogram abnormalities, blepharitis
Folic acid		Macrocytic anaemia, thrombocytopenia and megaloblastic bone marrow
Vitamin B₁₂		Subacute combined degeneration, macrocytic anaemia
Vitamin C, ascorbic acid	Scurvy	Poor wound healing, fatigue, limb pain, shortness of breath, difficulty sleeping, gingivitis, perifollicular purpura, hyperkeratosis
Vitamin D, ergo-/cholecalciferol	Rickets/osteomalacia	Bone pain, proximal myopathy
Vitamin E, tocopherol		Haemolysis, posterior column signs, ataxia, muscle wasting, retinitis pigmentosa-like changes, night blindness
Vitamin K, phylloquinone and other menaquinones		Bruising, purpura, nose and GI bleeds
Trace elements
Iron		Koilonychia, smooth tongue, anaemia, oesophageal web
Zinc	Acrodermatitis enteropathica	Peristomal/perinasal/perineal erythema, thin hair, diarrhoea, apathy, anorexia, growth failure, hypoglycaemia
Copper		Microcytic hypochromic anaemia, neutropenia, scurvy-like bone lesions, osteoporosis
Chromium		Peripheral neuropathy, hyperglycaemia
Selenium		Cardiomyopathy
Iodine		Goitre

Table 12.2 World Health Organization classification of body weight

Category	BMI/Quetelet index
Underweight	<18.5
Healthy weight	18.5-24.9
Overweight	25-29.9
Moderately obese	30-34.9
Severely obese	35-39.9
Morbidly obese	>40

If height cannot be measured, there are nomograms which relate the length of the forearm (ulna) or knee height (knee to heel) to the true height. In addition, the state of nourishment can be assessed by the more specialized measurements of mid-upper arm circumference (MUAC), skin-fold thickness and waist and waist/hip ratio. All UK hospital inpatients are now assessed for the risk of malnutrition by nursing staff using the Malnutrition Universal Screening Tool (MUST). This involves estimating BMI, and then adding on a score for the degree that any weight loss was unexpected and a score for the degree of acute illness. The final score is used to trigger full dietary assessment and treatment in those who need it.

Physical examination of the GI tract and abdomen

General signs

Systemic features of GI disease may be evident on general examination. Peripheral signs of chronic liver disease are listed in Box 12.3. Of these, the most common and useful are spider naevi (Fig. 12.1) (the presence of up to five small ones can be normal) and palmar erythema (Fig. 12.2) (the blotchy appearance often being more important than the overall redness). Inflammatory bowel disease may give rise to clubbing of the hands, arthritis, uveitis and skin changes including erythema nodosum (tender raised red lumps on the extensor surface of the limbs) and the much rarer pyoderma gangrenosum. Anaemia accompanies many GI diseases, as does oedema, and lymphadenopathy can be secondary to GI malignancy.

Figure 12.1 A typical spider naevus, with a central arteriole and fine radiating vessels.

Figure 12.2 Palmar erythema in chronic liver disease (sparing the centre of the palms).

It is helpful when examining the patient, recording in notes or communicating information to colleagues to remember the surface anatomy of the structures related to the GI tract and abdomen (Figs 12.3 and 12.4) and to think of the abdomen as divided into regions (Fig. 12.5). The two lateral vertical planes pass from the femoral artery below to cross the costal margin close to the tip of the ninth costal cartilage. The two horizontal planes, the subcostal and interiliac, pass across the abdomen to connect the lowest points on the costal margin and the tubercles of the iliac crests, respectively.

Figure 12.3 Anterior view of the external relations of the abdominal and thoracic organs.

Figure 12.4 Posterior view of the external relations of the abdominal and thoracic organs. The liver is not shown.

Figure 12.5 Regions of the abdomen. 1 and 3, right and left hypochondrium; 2, epigastrium; 4 and 6, right and left lumbar; 5, umbilical; 7 and 9, right and left iliac; 8, hypogastrium or suprapubic.

Remember that the area of each region will depend on the width of the subcostal angle and the proximity of costal margin to iliac crest, in addition to other features of bodily habitus which vary greatly from one patient to the next.

Inspection

The patient should be lying supine with arms loosely at the sides, the head and neck supported by up to two pillows, sufficient for comfort (Fig. 12.6). A sagging mattress makes examination difficult, particularly palpation. Make sure there is a good light, that the room is warm and that the hands are warm. A shivering patient cannot relax and vital signs, especially on palpation, may be missed.

Figure 12.6 Position of the patient and exposure for abdominal examination. Note that the genitalia should only be exposed when necessary.

Stand on the patient’s right side and expose the abdomen by turning down all the bed clothes except the upper sheet. The clothing should then be drawn up to just above the xiphisternum and the sheet folded down to the level of the symphysis pubis. Traditional teaching was to expose the patient ‘from nipples to knees’, but in the modern era when patient dignity is of paramount importance, this approach is not acceptable. However, inspection of the groins and genitalia must not be neglected and needs to be carried out with discretion, with full explanation as to the reasons, and leaving these areas exposed for the minimum time. It is not unusual for a patient to present with intestinal obstruction due to a strangulated femoral or inguinal hernia where the diagnosis has been missed initially due to lack of proper inspection of the groins in an effort to save embarrassment. Inspection is an important and neglected part of abdominal examination. Initially, it is well worthwhile spending 30 seconds observing the abdomen from different positions to note the following features:

Shape

Is the abdomen of normal contour and fullness, or distended? Is it scaphoid (sunken)?

Generalized fullness or distension may be due to fat, fluid, flatus, faeces or fetus.

Localized distension may be symmetrical and centred around the umbilicus as in the case of small bowel obstruction, or asymmetrical as in gross enlargement of the spleen, liver or ovary.

Make a mental note of the site of any such swelling or distension; think of the anatomical structures in that region and note if there is any movement of the swelling, either with or independent of respiration.

Remember that chronic urinary retention may cause palpable enlargement in the lower abdomen.

A scaphoid abdomen is seen in advanced stages of starvation and malignant disease.

The umbilicus

Normally the umbilicus is slightly retracted and inverted. If it is everted, then an umbilical hernia may be present and this can be confirmed by feeling an expansile impulse on palpation of the swelling when the patient coughs. The hernial sac may contain omentum, bowel or fluid. A common finding in the umbilicus of elderly obese people is a concentration of inspissated desquamated epithelium and other debris (omphalolith).

Movements of the abdominal wall

Normally there is a gentle rise in the abdominal wall during inspiration and a fall during expiration; the movement should be free and equal on both sides. In generalized peritonitis, this movement is absent or markedly diminished (the ‘still, silent abdomen’). To aid the recognition of intra-abdominal movements, shine a light across the patient’s abdomen. Even small movements of the intestine may then be detected by alterations in the pattern of shadows cast over the abdomen.

Visible pulsation of the abdominal aorta may be noticed in the epigastrium and is a frequent finding in nervous, thin patients. It must be distinguished from an aneurysm of the abdominal aorta, where pulsation is more obvious and a widened aorta is felt on palpation.

Visible peristalsis of the stomach or small intestine may be observed in three situations:

1 Obstruction at the pylorus. Visible peristalsis may occur where there is obstruction at the pylorus produced either by fibrosis following chronic duodenal ulceration or, less commonly, by carcinoma of the stomach in the pyloric antrum. In pyloric obstruction, a diffuse swelling may be seen in the left upper abdomen but, where obstruction is longstanding with severe gastric distension, this swelling may occupy the left mid and lower quadrants. Such a stomach may contain a large amount of fluid and, on shaking the abdomen, a splashing noise is usually heard (’succussion splash’). This splash is frequently heard in healthy patients for up to 3 hours after a meal, so enquire when the patient last ate or drank. In congenital pyloric stenosis of infancy, not only may visible peristalsis be apparent but also the grossly hypertrophied circular muscle of the antrum and pylorus may be felt as a ‘tumour’ to the right of the midline in the epigastrium. Both these signs may be elicited more easily after the infant has been given a feed. Standing behind the child’s mother with the child held on her lap may allow the child’s abdominal musculature to relax sufficiently to feel the walnut-sized swelling.

2 Obstruction in the distal small bowel. Peristalsis may be seen where there is intestinal obstruction in the distal small bowel or coexisting large and small bowel hold-up produced by distal colonic obstruction, with an incompetent ileocaecal valve allowing reflux of gas and liquid faeces into the ileum. Not only is the abdomen distended and tympanitic (hyper-resonant) but the distended coils of small bowel may be visible in a thin patient and tend to stand out in the centre of the abdomen in a ‘ladder pattern’.

3 As a normal finding in very thin, elderly patients with lax abdominal muscles or large, wide-necked incisional herniae seen through an abdominal scar.

Skin and surface of the abdomen

In marked abdominal distension, the skin is smooth and shiny. Striae atrophica or gravidarum are white or pink wrinkled linear marks on the abdominal skin. They are produced by gross stretching of the skin with rupture of the elastic fibres and indicate a recent change in size of the abdomen, such as is found in pregnancy, ascites, wasting diseases and severe dieting. Wide purple striae are characteristic of Cushing’s syndrome and excessive steroid treatment.

Note any scars present, their site, whether they are old (white) or recent (red or pink), linear or stretched (and therefore likely to be weak and contain an incisional hernia). Common examples are given in Fig. 12.7.

Figure 12.7 Some commonly used abdominal incisions. The midline and oblique incisions avoid damage to the innervation of the abdominal musculature and the later development of incisional hernia.

Look for prominent superficial veins, which may be apparent in three situations (Fig. 12.8): thin veins over the costal margin, usually of no significance; occlusion of the inferior vena cava; and venous anastomoses in portal hypertension. Inferior vena caval obstruction not only causes oedema of the limbs, buttocks and groins but, in time, distended veins on the abdominal wall and chest wall appear. These represent dilated anastomotic channels between the superficial epigastric and circumflex iliac veins below, and the lateral thoracic veins above, conveying the diverted blood from the long saphenous vein to the axillary vein; the direction of flow is therefore upwards. If the veins are prominent enough, try to detect the direction in which the blood is flowing by occluding a vein, emptying it by massage and then looking for the direction of refill. Distended veins around the umbilicus (caput medusae) are uncommon but signify portal hypertension, other signs of which may include splenomegaly and ascites. These distended veins represent the opening up of anastomoses between portal and systemic veins and occur in other sites, such as oesophageal and rectal varices.

Figure 12.8 Prominent veins of the abdominal wall.

Pigmentation of the abdominal wall may be seen in the midline below the umbilicus, where it forms the linea nigra and is a sign of pregnancy. Erythema ab igne is a brown mottled pigmentation produced by constant application of heat, usually a hot water bottle or heat pad, on the skin of the abdominal wall. It is a sign that the patient is experiencing severe ongoing pain such as from chronic pancreatitis.

Finally, uncover and inspect both groins, and the penis and scrotum of a male, for any swellings and to ensure that both testes are in their normal position. Then bring the sheet back up to the level of the symphysis pubis.

Palpation

Palpation forms the most important part of the abdominal examination. Tell the patient to relax as best he can and to breathe quietly, and assure him that you will be as gentle as possible. Enquire about the site of any pain and come to this region last. These points, together with unhurried palpation with a warm hand, will give the patient confidence and allow the maximum amount of information to be obtained.

When palpating, the wrist and forearm should be in the same horizontal plane where possible, even if this means bending down or kneeling by the patient’s side. The best palpation technique involves moulding the relaxed right hand to the abdominal wall, not to hold it rigid (Fig. 12.9). The best movement is gentle but with firm pressure, with the fingers held almost straight but with slight flexion at the metacarpophalangeal joints and certainly avoiding sudden poking with the fingertips (Fig. 12.10).

Figure 12.9 Correct method of palpation. The hand is held flat and relaxed and ‘moulded’ to the abdominal wall.

Figure 12.10 Incorrect method of palpation. The hand is held rigid and mostly not in contact with the abdominal wall.

Palpation of intra-abdominal structures is an imperfect process in which the great sensitivity of the sense of touch and pressure is heavily masked by the abdominal wall tissue. It is unusual for structures to be very easily palpable and so it is necessary to concentrate fully on the task and to try and visualize the normal anatomical structures and what might be palpable beneath the examining hand. It may be necessary to repeat the palpation more slowly and deeply. Putting the left hand on top of the right allows increased pressure to be exerted (Fig. 12.11), such as with an obese or very muscular patient.

Figure 12.11 Method of deep palpation in an obese, muscular or poorly relaxed patient.

A small proportion of patients find it impossible to relax their abdominal muscles when being examined. In such cases, it may help to ask them to breathe deeply, to bend their knees up or to distract their attention in other ways. No matter how experienced the examiner, little will be gained from palpation of a poorly relaxed abdomen.

It is helpful to have a logical sequence to follow and, if this is done as a matter of routine, then no important point will be omitted. The following scheme is suggested, which may need to be varied according to the site of any pain:

All the organs in the upper abdomen (liver, spleen, kidneys, stomach, pancreas, gallbladder) move downward with inspiration (with the spleen moving more downwards and medially). Thus, asking the patient to take a deep breath while examining makes detection of these organs easier since something that is moving is easier to detect than something stationary. However, to avoid confusing one’s sensation, when the patient breathes the examining hand should be still so that the organ in question ‘comes onto the examining hand’, or ‘slips by underneath it’.

Left kidney

The right hand is placed anteriorly in the left lumbar region while the left hand is placed posteriorly in the left loin (Fig. 12.12). Ask the patient to take a deep breath in, press the left hand forward and the right hand backward, upward and inward. The left kidney is not usually palpable unless either low in position or enlarged. Its lower pole, when palpable, is felt as a rounded firm swelling between both right and left hands (i.e. bimanually palpable) and it can be pushed from one hand to the other, in an action which is called ‘ballotting’.

Figure 12.12 Palpation of the left kidney.

Spleen

Like the left kidney, the spleen is not normally palpable. It has to be enlarged to two or three times its usual size before it becomes palpable, and then is felt beneath the left subcostal margin. Enlargement takes place in a superior and posterior direction before it becomes palpable subcostally. Once the spleen has become palpable, the direction of further enlargement is downwards and towards the right iliac fossa (Fig. 12.13). Place the flat of the left hand over the lower-most rib cage posterolaterally, thus restricting the expansion of the left lower ribs on inspiration and concentrating more of the inspiratory movement into moving the spleeen downwards. The right hand is placed beneath the costal margin well out to the left. Press in deeply with the fingers of the right hand beneath the costal margin, at the same time exerting considerable pressure medially and downwards with the left hand (Fig. 12.14), and then ask the patient to breathe in deeply. Repeat this manoeuvre with the right hand being moved more medially beneath the costal margin on each occasion (Fig. 12.15). If enlargement of the spleen is suspected from the history and it is still not palpable, turn the patient half on to the right side, ask him to relax back onto your left hand, which is now supporting the lower ribs, and repeat the examination as above. Alternatively the spleen may be very large and the lower edge may be much lower than at first suspected. It may help to ask the patient to place the left hand on your right shoulder while palpating for the spleen.