Upper gastrointestinal series 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. 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
Colon cleansing tubes to inject water, sometimes mixed with herbs or with other liquids, into the colon via the rectum using special equipment. Oral cleaning regimens use dietary fiber, herbs, dietary supplements, or laxatives. People who practice colon cleansing believe that accumulations of putrefied feces line the walls of the large intestine and that these accumulations harbor parasites or pathogenic gut flora, causing nonspecific symptoms and general ill-health. This "auto-intoxication" hypothesis is based on medical beliefs of the Ancient Egyptians and Greeks and was discredited in the early 20th century. There is no scientific evidence for the alleged benefits of colon cleansing.