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An upper gastrointestinal series, also called an upper gastrointestinal study or contrast radiography of the upper gastrointestinal tract, 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. 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.〔 == Types of barium-contrast imaging== 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. 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). 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.〔 *Barium swallow X-ray examinations are used to study the pharynx and esophagus.〔 *Barium meal examinations are used to study the lower esophagus, stomach and duodenum.〔 *Barium follow through examinations are used to study the small intestine.〔 *Enteroclysis also called small bowel enema is a Barium X-ray examination used to display individual loops of the small intestine by intubating the jejunum with a small tube and administering Barium sulfate followed by methylcellulose or air.〔 *Barium enema examinations are used to study the large intestine and rectum and are classified as Lower gastrointestinal series.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「upper gastrointestinal series」の詳細全文を読む スポンサード リンク
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