I had a similar concern with sedation and anesthesia. I did have a small mess after an upper GI endoscopy. For bigger procedures I mentioned my concern to the nurse and was reassured by them and didn’t find anything to clean up. I’m guessing that they might have cleaned me up, but I was asleep at the time. I have always emptied my pouch immediately before climbing up on the gurney. Eating a light dinner or skipping it might be helpful, and letting the nurse know of the possibility would also be wise.