Colonoscopies, for whatever reason, you have to have someone physically present at all times. Normally, they make you wait in the waiting room, and even if you need to step out to use the restroom across the hall, you have to let the staff know where you're going. No leaving for lunch, no "I'll be back in 30 minutes," none of that.Why aren't you allowed to drive off and come back?
I suppose if things go bad in a hurry, they want someone there on the spot. I don't really know.