double-contrast barium enema double-contrast barium enema a double-contrast barium enema is a form of contrast radiography in which x-rays of the colon and rectum are taken using two forms of contrast to make the structures easier to see. a liquid containing barium (that is, a radiocontrast agent) is put into the rectum. barium is a silver-white metallic compound that outlines the colon and rectum on an x-ray and helps show abnormalities. air is also put into the rectum and colon to further enhance the x-ray. double-contrast barium enemahuman intestinal tract, as imaged via double-contrast barium enemapurposeradiography which uses 2 forms of contrast for better image double-contrast barium enemas are less invasive than a colonoscopy and have comparatively fewer issues in a viable large bowel.