have you ever considered a CT colonography? the accuracy of detection is similar, the test is less risky, and it is less unpleasant. there is the radiation component, but if you only get radiated every few years and otherwise live a well-balanced life, it's worth it. there is, of course, a question of whether colon screening is necessary at all.

this is only one article of many, via quick search; i myself wud go for CT colonography if i am still inclined to follow the traditional medical screening recommendation by that age. i also think that the rate of complications after colonoscopy in the community is severely underestimated and depends on the operator of the scope. procedures bill higher than prescriptions and recommendations, so scope operators are incentivized to do more and inevitably do them even if tired or angry. additionally, there is a constant debate on how big a polyp shud be before cutting it out... note, just like with colonoscopy, it is best to go to a center that does a lot of CT colonographies and have readers that interpret the results every day. (btw, barium enema is not the same, and worthless for polyp screening)

Just refuse to do it! They cannot make you do it, and, it appears that once you start, they like to bend you over many more times. Just say “NO!” Why do you need to take the risks involved, unless you already have a large problem.