I've had two of them, the last a couple of weeks ago. I wore undershorts as insurance against leakage, but they weren't necessary. The prep stuff pretty much cleaned me out of anything that might leak.
I suggest that you read Dave Barry's column on colonoscopies. It's hilarious and accurate:
https://www.miamiherald.com/living/liv-columns-blogs/dave-barry/article1928847.html
Well, maybe not entirely accurate, although it rings true, like this passage:
"And then, when you figure you must be totally empty, you have to drink another liter of MoviPrep, at which point, as far as I can tell, your bowels travel into the future and start eliminating food that you have not even eaten yet."
I have one every other year due to being at risk. Had 4 now and have not had any leakage. As everyone has mentioned.. The worse part is the prep.
Luxury. After 20 years in the risk zone I now get one every year. I think I've had 15 so far. They really aren't that big of a deal. Even the prep has gotten easier once I learned to mix the "powdered fun" with yellow Gatorade instead of water. C will be getting her first this year, but she's gotten to witness most of my preps.
My experience is pretty much the same as others here - the prep is just awful but the actual procedure and is over before you know it and you can't wait to eat something and start drinking coffee again!
I cant wait to drink Margaritas again, but have to wait until the next day.