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 support, "auto-intoxication" persists in the public imagination. The practice of colon cleansing has undergone a resurgence in the alternative-medical community, supported by testimonials and anecdotal evidence and promoted by manufacturers of colon-cleansing products. In the United States the Food and Drug Administration (FDA) regulates the production of equipment used in colon hydrotherapy in the USA but does not regulate their use, or the supplements used in oral colon-cleansing regimens and manufacturer claims do not require verification or supporting evidence. The contents of the products are also not verified or tested. The FDA has issued several letters warning manufacturers and suppliers