"Doppelkontrast" könnte das sein;

"double contrast barium enema" habe ich in diesem Zusammenhang auch gefunden.


https://pubs.rsna.org/doi/10.1148/54.4.541
Since the description of the technic for double-contrast examination of the colon by Fischer (1) in 1923, barium sulfate, with or without the addition of various other agents, has been the chief medium used in such studies.
https://pubs.rsna.org/doi/10.1148/54.4.541

There are many procedures that can identify abnormalities in the colon. A double contrast barium enema uses a silver-white compound called barium to outline the colon and rectum on an x-ray. Normally, soft tissues x-ray very poorly, but the barium coating reveals a clear outline of the colon. While the double contrast barium enema is not as comprehensive as the colonoscopy, it is a very useful tool to help diagnose many colorectal issues.Barium enemas are low risk procedures, which are less invasive and often more affordable than a colonoscopy.