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 or a "colonic", is a treatment which is used "to wash out the contents of the large bowel by means of copious enemas using water or other medication." During an enema, the water is retained in the colon for approximately 15 minutes. During a colonic, water is introduced into the colon and then it is flushed out and this is repeated until the entire colon is cleared. Colonic irrigation has been described as an "unwise" procedure as it carries the risk of serious harm and has no proven benefit. The consumer advocacy news program Marketplace conducted a consumer trial with