Lower gastrointestinal series Lower gastrointestinal series A lower gastrointestinal series is a medical procedure used to examine and diagnose problems with the human colon (large intestine). Radiographs (X-ray pictures) are taken while barium sulfate, a radiocontrast agent, fills the colon via an enema through the rectum. The term barium enema usually refers to a lower gastrointestinal series, although enteroclysis (an upper gastrointestinal series) is often called a small bowel barium enema. This test may be done in a hospital or clinic. The patient lies on the X-ray table and a preliminary X-ray is taken. The patient is then asked to lie on the
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,