TESTS OF STRUCTURE: IMAGING - Гастроэнтерология (анг,рус) - Конспект лекций
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Гастроэнтерология (анг,рус)

TESTS OF STRUCTURE: IMAGING

Plain radiographs of the abdomen show the distribution of gas within the small and large intestines and are useful in the diagnosis of intestinal obstruction or paralytic ileus where dilated loops of bowel and (in the erect position) fluid levels are seen. The outlines of soft tissues such as liver, spleen and kidneys may be visible, and calcification of these organs as well as pancreas, blood vessels, lymph nodes and calculi may be detected. A chest radiograph shows the diaphragm, and erect films may detect subdiaphragmatic free air in cases of perforation. Unexpected pulmonary problems such as pleural effusions will also be revealed.

Contrast studies

Barium sulphate is inert and provides good mucosal coating and excellent opacification. Water-soluble contrast is used to opacify bowel prior to abdominal computed tomography and in cases of suspected perforation but is less radio-opaque and is also irritant if aspirated into the lungs. Contrast studies are carried out under fluoroscopic control, which allows assessment of motility and correct patient positioning. The double contrast technique improves mucosal visualisation by using gas to distend the barium-coated intestinal surface.

Barium studies are useful for detecting filling defects, which may be intraluminal (e.g. food or faeces), intramural (e.g. carcinoma) or extramural (e.g. lymph nodes). Strictures, erosions, ulcers and motility disorders can all be detected.

Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI)

These are increasingly used in the evaluation of intra-abdominal disease. They are non-invasive and offer detailed images of the abdominal contents.

 

 

 

 

Table 1. Ultrasound scanning, CT and MRI in gastroenterology.

Endoscopy

In recent years video endoscopy has replaced fibreoptic endoscopes. Images are displayed on a colour monitor. An increasing array of instruments can be passed down the endoscope to allow both diagnostic and therapeutic procedures.

 

Upper gastrointestinal endoscopy

After the patient has fasted for at least 4 hours, this is performed under light intravenous benzodiazepine sedation, or using only local anaesthetic throat spray. With the patient in the left lateral position the entire oesophagus (excluding pharynx), stomach and first two parts of duodenum can be seen. Indications, contraindications and complications are given in Table 2.

Table 2.                                                    Table 3.

 

Enteroscopy

Using a longer endoscope (enteroscope) it is possible to visualise a large portion of the small intestine. Enteroscopy is of special value in the assessment of obscure, recurrent gastrointestinal bleeding.

Sigmoidoscopy can be carried out either in the outpatient clinic using a 20 cm rigid plastic sigmoidoscope or in the endoscopy suite using a 60 cm flexible instrument following a disposable enema for bowel preparation. When sigmoidoscopy is combined with proctoscopy, accurate detection of haemorrhoids, ulcerative colitis and distal colorectal neoplasia is possible. After full bowel cleansing it is possible to examine the entire colon and often the terminal ileum using a longer colonoscope. Indications, contraindications and complications of colonoscopy are listed in Table 3.

Endoscopic retrograde cholangiopancreatography (ERCP)

Using a side-viewing duodenoscope, it is possible to cannulate the main pancreatic duct and common bile duct. The procedure is valuable in defining the ampulla of Vater, biliary tree and pancreas. Its main uses include investigation of obstructive jaundice, biliary pain and suspected pancreatic disease, such as chronic pancreatitis and pancreatic cancer. Obstruction of the common bile duct by stones can be treated by stone extraction after sphincterotomy, and strictures may be stented. The procedure is technically demanding and carries a significant risk of pancreatitis (3-5%), haemorrhage (4% after sphincterotomy) and perforation (1%).

 

TESTS OF INFECTION

Bacterial cultures

Stool cultures are essential in the investigation of diarrhoea, especially when it is acute or bloody, to identify pathogenic organisms.

Serology

Detection of antibodies plays a limited role in the diagnosis of gastrointestinal infection caused by organisms such as Helicobacter pylori, Salmonella species and Entamoeba histolytica.

Breath tests

Non-invasive breath tests for H. pylori infection (detection of the radioisotope in expired air).

 

TESTS OF FUNCTION

A number of dynamic tests can be used to investigate aspects of gut function, including digestion, absorption, inflammation and epithelial permeability. In the assessment of suspected malabsorption, blood tests (full blood count, erythrocyte sedimentation rate (ESR), folate, B12, iron status, albumin, calcium and phosphate) are essential.

Gastrointestinal motility

A range of diverse radiological, manometric and radioisotopic tests exist for investigation of gut motility but many are research tests of limited value in daily clinical practice.

Oesophageal motility

A careful barium swallow can give useful information about oesophageal motility. Oesophageal manometry, often in conjunction with 24-hour pH measurements, is of value in diagnosing cases of refractory gastro-oesophageal reflux, achalasia and non-cardiac chest pain.

Gastric emptying

Delayed gastric emptying (gastroparesis) may be responsible for some cases of persistent nausea, vomiting, bloating or early satiety. Endoscopy and barium studies are often normal.

 

The most common complaints of gastrointestinal diseases are:

·         Dysphagia

·         Heartburn

·         Regurgitation, cructio

·         Indigestion

·         Flatulence

·         Nausea

·         Vomiting

·         Anorexia

·         Abdominal pain

·         Diarrhea

·         Constipation

·         Gain and loss in weight

·         Gastrointestinal bleeding

 

Dysphagia is defined as difficulty in swallowing.

It should be distinguished from both globus sensation (in which anxious people feel a lump in the throat without organic cause) and odynophagia (which refers to pain with swallowing, usually resulting from oesophagitis due to gastrooesophageal reflux or candidiasis).

Dysphagia can be classified into oropharyngeal and oesophageal causes.

Oropharyngeal dysphagia: Difficulty in transferring food from the mouth to the esophagus, often associated with symptoms of nasopharyngeal regurgitation and pulmonary aspiration. It is typically caused by neuromuscular or structural disorders involving the oropharynx and proximal esophagus.

Esophageal dysphagia: The sensation of difficulty in passage of food down the                                           esophagus.   Oesophageal causes include structural disease (benign or malignant strictures) and dysmotility of the oesophagus.

 

Fig. 1. Investigation of dysphagia.

Heartburn is a specific burning sensation behind of sternum associated with regurgitation of gastric contents into the inferior portion of the esophagus.

Occasional heartburn is common in normal person, but frequent and severe heartburn is generally a manifestation of esophageal dysfunction.

Heartburn is most often associated with gastroesophageal reflux. It arises also in various diseases of the alimentary tract with hyperacidity – gastritis, peptic ulcer disease, cholecystitis, hiatus hernia, and in pregnancy.

Regurgitation is return of the part of swallowed food into the mouth due to backward movement of esophagus with open cardia without contraction of diaphragm and abdominal muscles.

1.      By air (eructation): during the fast meals (aerophagy), heard at a distance, odorless.

2.      By food or by gas (regurgitation): due to motor dysfunction of the stomach with increased formation of gas due to abnormal:

·         Fermentation: odorless or smell of sour, or bitter oil; usually associated with hypersecretion of gastric juice and occurs during pain attacks in ulcer; can also occur in normal or insufficient secretion of the stomach in failure of the cardia, when the stomach contents are regurgitated into the esophagus.

·         Putrefaction:  odor of rotten eggs, that indicates intensive degradation of proteins; it can be due to pylorus stenosis with great distension of the somach and significant congestion in it.

Indigestion (dyspepsia) is a symptom that includes epigastric pain, heartburn, distension, nausea or 'an acid feeling' occurring after eating or drinking. The symptom is subjective and frequent. In many patients there is no demonstrable cause, but it may be associated with Helicobacter infection, peptic ulceration, acid reflux, and occasionally upper gastrointestinal malignancy.

Flatulence describes excessive wind. It is associated with belching, abdominal distension and the passage of flatus per rectum. It is only infrequently associated with organic disease of the gastrointestinal tract, but usually represents a functional disturbance, some of which is due to excessive swallowed air. In some patients it is clearly related to certain foods, such as vegetables.

 

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