I had my second colonoscopy done about a year ago, as well as an upper endoscopy after a few episodes of trouble swallowing food. My biggest issue with a colonoscopy is the prep, that stuff that they make you drink is vomitable.
The first time I didn't drink enough of it to "do the job" properly, so we had to reschedule the procedure. The second time I managed to gag it down, and the procedure went fine. They removed some polups, but they were all benign. This was about 6 years ago.
When my doctor said I was due for another colonoscopy, he said he'd check me out "top to bottom" at the same time. Great.
I asked him if there was any other way to prep for the test other than that liquid, and believe it or not, they now have one where you take a dozen pills with a quart of water the day before, and the morning of the procedure. This was a piece of cake compared to that other vile liquid.
Ask your doctor for this prep method from now on.