Abdominal x-ray as a scout film for other procedures such as barium enemas. An upper gastrointestinal series is where a contrast medium, usually a radiocontrast agent such as barium sulfate barium salt 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. A lower gastrointestinal series is where radiographs are taken while barium sulfate, a radiocontrast agent, fills the colon via an
Lower gastrointestinal series colon to distend it and provide better images (often called a "double-contrast" exam). If air is used, the enema tube will be reinserted if it had been removed and a small amount of air will be introduced into the colon, and more X-ray pictures are taken. The patient is usually asked to move to different positions and the table is slightly tipped to get different views. If there is a suspected bowel perforation, a water-soluble contrast agent is used instead of barium. The procedure is otherwise very similar, although the images will be of poorer quality. If a perforation exists,