Being old, I recently went in for my second colonoscopy (the recommended interval for those not of high risk is every 10 years, starting at age 50). The first time, I just went in without doing a lot of research, and got knocked out by whatever anesthetic they used, and came to later, woozy and sick, not remembering anything.
This time I asked for a sedation-free procedure. Everyone in the GI department at Somerville Hospital was accomodating--they clearly didn't think it was the best idea, but no one tried to pressure me out of it. In fact, everything about my experience belied the stereotype of overly busy health facilities without time for patients. The physician doing the procedure sat down, introduced herself, and talked through the procedure. The nursing staff was cheery and solicitous. They did talk a bit too much about food (this was right before Thanksgiving), and I had been on a fast for a day and a half by that point.
The procedure did hurt a couple of times. You have to pump air in (actually carbon dioxide in this case, which gets absorbed, and avoids some post-procedure pain) to get the colonoscope around bends in the colon, and that's what hurts. It feels like an extremely bad cramp. I would relax and breathe deeply until she was around the bend. The whole thing took maybe fifteen minutes, and I could get up and leave. Plus I got to watch the ride through my smooth, pink insides ("that's the entrance to your appendix!") on the big screen.
A couple of points. The physician pointed out that some people, particularly women, have twistier colons (she knotted up her stethoscope to demonstrate). More bends=more pain. While my plots are twisty, clearly my colon is a Roman road. If you try your colonoscopy without sedation based on this account, be aware that you may feel more pain than I did, depending on your anatomy.
But the second point is more complex. How much pain do various people feel? And how does it affect them emotionally? Various staff members made remarks about how tough I was being. Everyone was genuinely concerned that I would be in pain, that I would suffer because of what they were doing.
I could have tolerated a fair amount more--a couple more bends, with a bit more pressure. How to judge when it would have been more than I wished to endure? No one knows, the reason they were reluctant to accept that I would be fine. They did put a line in so they could give me some sedation if it grew to be too much.
Now, I regularly do things like hike, gasping, up mountains with a pack on my back, in a certain amount of pain for much of a day. And I do this for fun. That it hurts is, weirdly, part of that fun. In my younger days I often hiked with horrendous blisters. Definitely not part of the fun, but something I just took for granted. I've gotten a bit smarter since then, so that is a pain I avoid now. I do avoid pain when I can. Really.
I think it is also conditioned by your expectations. I expected a few moments of fairly severe pain, and it was a bit less severe than I expected, so it was fine. Plus, all the pain came at the beginning, as the colonoscope went in, with no pain at all in the latter part, the actual examination, as it came back out. I don't know if that's what it's always been like, but that's the perfect way to structure the experience so you remember it...well, not fondly, but with equanimity.
So, should you try it? It does hurt, no question, but really not that much, and it's really quite an interesting experience. Thought I'm certainly willing to wait another decade to have it again.