Eh? You definitely don't need general anesthetic, they tend to offer sedation if you want it and you might well dose off during that but there is no need to have a general anesthetic for a colonoscopy.
If it's just the colonoscopy then it's fine, I had one during lockdown so I didn't really want to have anyone come and collect me given hospitals were hotbeds of covid infections etc.. (you have to have someone collect you with the sedation, it's not just the longer wait) so I opted to go without.
It was fine, super quick procedure, doesn't matter if you're fully conscious vs drowsy, at one point I hadn't taken many breaths of the laughing gas and it was still fine, only a slight bit of pain towards the end.
I'd not advise it if they have to look down your throat too though, you'll probably want some sedation for that as it's quite uncomfortable - you also have some mild pain relief spray for that where they numb your throat a bit.
One thing that got me was they changed the instructions on the laxatives/bowel prep stuff, I wish I'd just followed the printed instructions not the handwritten notes the nurse or someone had added to the packet giving me different times to take them, by the time I got the hopsital in the morning I needed to go again... was still unleashing a nasty mess in the hospital toilets at the last minute before the scope...
But then in the actual room, as I was fully conscious, the guy was complimenting me on my bowel prep! You have very clear bowels there Mr Dowie. Could watch the whole thing on the monitor.