Me I was told that the contrast fluids have an evacuation agent in them to help clear the barium out of your system. When you arrive for the scan ask them if one contrast fluid is better for folks who have constipation.I didn't have any constipation issues either when I drank it.. but I'm a D-Type. So that doesn't mean much. So don't be shy.. ask!And I agree.. the CT Scan was a snap and quick too.All the best.BQ