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
Sigmoid colon Sigmoid colon The sigmoid colon (pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 35–40 cm (13.78-15.75 in) in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus "sigma" + "-oid"). This part of the colon normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity. The sigmoid colon begins at the superior aperture of the lesser pelvis, where it is continuous with the