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Radiographs used to examine abnormalities of the digestive system excluding the colon From Wikipedia, the free encyclopedia
An upper gastrointestinal series, also called a barium swallow, barium study, or barium meal, is a series of radiographs used to examine the gastrointestinal tract for abnormalities. A contrast medium, usually a radiocontrast agent such as barium sulfate mixed with water, is ingested or instilled into the gastrointestinal tract, and X-rays are used to create radiographs of the regions of interest. The barium enhances the visibility of the relevant parts of the gastrointestinal tract by coating the inside wall of the tract and appearing white on the film. This in combination with other plain radiographs allows for the imaging of parts of the upper gastrointestinal tract such as the pharynx, larynx, esophagus, stomach, and small intestine such that the inside wall lining, size, shape, contour, and patency are visible to the examiner. With fluoroscopy, it is also possible to visualize the functional movement of examined organs such as swallowing, peristalsis, or sphincter closure. Depending on the organs to be examined, barium radiographs can be classified into "barium swallow", "barium meal", "barium follow-through", and "enteroclysis" ("small bowel enema"). To further enhance the quality of images, air or gas is sometimes introduced into the gastrointestinal tract in addition to barium, and this procedure is called double-contrast imaging. In this case the gas is referred to as the negative contrast medium. Traditionally the images produced with barium contrast are made with plain-film radiography, but computed tomography is also used in combination with barium contrast, in which case the procedure is called "CT enterography".[1]
| Upper gastrointestinal series | |
|---|---|
Normal barium swallow fluoroscopic image, showing the ingested barium sulfate being induced down the oesophagus by peristalsis. | |
| Synonyms | Upper gastrointestinal study, contrast radiography of the upper gastrointestinal tract, barium swallow, barium meal |
| ICD-10-PCS | GroupMajor.minor [dead link] |
Various types of barium X-ray examinations are used to examine different parts of the gastrointestinal tract. These include barium swallow, barium meal, barium follow-through, and barium enema.[2] The barium swallow, barium meal, and barium follow-through are together also called an upper gastrointestinal series (or study), whereas the barium enema is called a lower gastrointestinal series (or study).[3] In upper gastrointestinal series examinations, the barium sulfate is mixed with water and swallowed orally, whereas in the lower gastrointestinal series (barium enema), the barium contrast agent is administered as an enema through a small tube inserted into the rectum.[2]
Barium X-ray examinations are useful tools for the study of appearance and function of the parts of the gastrointestinal tract. They are used to diagnose and monitor esophageal reflux, dysphagia, hiatus hernia, strictures, diverticula, pyloric stenosis, gastritis, enteritis, volvulus, varices, ulcers, tumors, and gastrointestinal dysmotility, as well as to detect foreign bodies.[3][6] Although barium X-ray examinations are increasingly being replaced by more modern techniques, such as computer tomography, magnetic resonance imaging, ultrasound imaging, endoscopy and capsule endoscopy,[7] barium contrast imaging remains in common use because it offers the advantages of greater affordability, wider availability,[1][5] and better resolution in assessing superficial mucosal lesions.[7][8]
Barium sulfate is swallowed and is a radio opaque substance that does not allow the passage of X-rays. As a result, areas coated by barium sulfate will appear white on an X-ray film. The passage of barium sulfate through the gastrointestinal tract is observed by a radiologist using a fluoroscope attached to a TV monitor. The radiologist takes a series of individual X-ray images at timed intervals depending on the areas to be studied. Sometimes medication which produces gas in the gastrointestinal tract is administered together with the Barium sulfate. This gas distends the gastrointestinal lumen, providing better imaging conditions and in this case the procedure is called double-contrast imaging.[9]
Clinical status and relevant medical history are reviewed prior to the studies.[10] Patient consent is required.[3]
A barium swallow study is also known as a barium esophagram and needs little if any preparations for the study of the larynx, pharynx, and esophagus when studied alone.[11][12]
Amongst the uses of barium swallow are: persistent dysphagia and odynophagia despite negative esophagogastroduodenoscopy (OGDS) findings, failed OGDS, esophageal motility disorder, globus pharyngis, assessment of tracheoesophageal fistula, and timed barium swallow to monitor the progress of esophageal achalasia therapy.[13] Barium sulfate suspension such as 100 ml or more of E-Z HD 200 to 250% concentration and Baritop 100% can be used. Water-soluble contrast agent such as Gastrografin (diatrizoate) and Conray (Iotalamic acid) is used instead of barium if oesophageal perforation is suspected. Low osmolar contrast medium with concentration of 300 mg/ml is used instead of gastrografin if there is risk of aspiration or there is tracheoesophageal fistula.[13]
A thick barium mixture is swallowed in supine position and fluoroscopic images of the swallowing process are made. Then several swallows of a thin barium mixture are taken and the passage is recorded by fluoroscopy and standard radiographs. The procedure is repeated several times with the examination table tilted at various angles. A total of 350–450 mL of barium is swallowed during the process.[14][15] Normally, 90% of ingested fluid should have passed into the stomach after 15 seconds.[16]
Right anterior oblique (RAO) view is to see the oesophagus clearly, away from overlapping spine.[13] AP (anterior-posterior) view is also done to visualise the gastroesophageal junction.[13] AP and lateral views are also done to visualise the hypopharynx during swallowing at a frame rate of 3–4 per second. Left posterior oblique (LPO) position is used to identify hernias, mucosal rings, and varices.[13]
Intravenous injection of Buscopan (Hyoscine butylbromide) 20 mg or glucagon 0.3 mg is used to distend the stomach and slow down the emptying of the contrast into the duodenum.[13]
Right anterior oblique (RAO) view is used to demonstrate antrum and greater curve of stomach. Supine position is to demonstrate antrum and body of stomach. Left anterior oblique (LAO) view is used to see the lesser curve of stomach en face. This position is also used to check for gastroesophageal reflux when patient is asked to cough or swallow (water siphon test). Left lateral tilted with head up 45 degrees is used to demonstrate the fundus of the stomach.[13] To demonstrate the duodenal loop, the subject can lie down in prone position on a compression pad to prevent excessive barium flowing into the duodenal loop. Anterior view of duodenal loop can be seen at RAO position.[13] Duodenal cap can be visualised by taking images when subject lie down in prone position, RAO, supine, and then LAO positions or it can be seen on erect position with RAO and steep LAO views.[13] Total mucosal coating of the stomach is done by asking the subject to roll to the right side into a complete circle until RAO position. Arae gastriae in the antrum (fine reticular network of grooves) is visible if good coating is achieved.[13]
Indications to do this procedure are: unexplained chronic abdominal pain with weight loss, unexplained diarrhea, anemia which is caused by gastrointestinal bleeding or dependent on blood transfusion where the cause cannot be explained despite OGDS or colonoscopy investigations, partial obstruction of bowel/small bowel adhesive obstruction suspected, and unexplained malabsorption of nutrients.[13] For barium follow-through examinations, a 6-hour period of fasting is observed prior to the study.[10]
Barium is administered orally, sometimes mixed with diatrizoic acid (gastrografin) to reduce transit time in the bowel. Intravenous metoclopramide is sometimes also added to the mixture to enhance gastric emptying.[17] 600 ml of 0.5% methylcellulose can be given orally, after barium meal is given, to improve the images of small bowel follow-through by reducing the time taken for barium to pass through the small intestines, and increase the transparency of the contrast-filled small bowels.[18] Other methods to reduce transit time are to add ice cold normal saline after the administration of barium saline mixture[19] or to give a dry meal.[20]
X-ray images are then taken in a supine position at intervals of 20–30 minutes. Real-time fluoroscopy is used to assess bowel motility. The radiologist may press or palpate the abdomen during images to separate intestinal loops. The total time necessary for the test depends on the speed of bowel motility or transit time and may vary between 1 and 3 hours.[17]
Enteroclysis is also known as small bowel enema.[21] It has been largely replaced by magnetic resonance enterography/enteroclysis[13] and computed tomography enterography/enteroclysis.[22]
In addition to fasting for 8 hours prior to examination, a laxative may also be necessary for bowel preparation and cleansing.[12] The main aim of this study is to distend the proximal bowel through infusion of large amount of barium suspension. Otherwise, the distension of distal small bowel is generally similar with small bowel follow-through. Therefore, there is a need to pass a tube through the nose into the jejunum (nasojejunal tube) to administer large amount of contrast. This can be unpleasant to the subject, requires more staff, longer procedural time, and higher radiation dose when compared to small bowel follow-through. The indications for enteroclysis are generally similar to small bowel follow-through. Barium suspensions such as diluted E-Z Paque 70% and Baritop 100% can be used. After that, 600 ml of 0.5% methylcellulose is administered after 500 ml of 70% barium suspension is given. Bilbao-Dotter tube and Silk tube can be used to administer barium suspension. The subject should be fasted overnight, any antispasmodic drugs should be stopped one day before the examination, and Tetracaine lozenges can be used 30 minutes before the procedure to numb the throat for nasojejunal tube insertion.[13]
The filling of the small intestines can be viewed continuously using fluoroscopy, or viewed as standard radiographs taken at frequent intervals. The technique is a double-contrast procedure that allows detailed imaging of the entire small intestine. However, the procedure may take 6 hours or longer to complete and is quite uncomfortable to undergo.[23]
Complete gastrointestinal obstruction is a contraindication for barium studies.[17]
Barium sulfate as a contrast medium was evolved from the prior use of bismuth preparations which were too toxic. The use of bismuth preparations had been described as early as 1898. Barium sulfate as a contrast medium in medical practice was introduced largely as a result of the works of Krause a director of the Bonn Polyclinic, now the medical faculty of the University of Bonn and his colleagues Bachem and Gunther. In a paper read in 1910 at the radiological congress they advocated for the use of barium sulfate as an opaque contrast medium in medicine.[36]
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