I have never had a colonoscopy, nor will I. The VA tried one when I turned 50, and gave me laxatives to use at home for 3 days, plus I couldn't eat solid food. I did as I was told, though I was miserable.
The day for the procedure came, and as soon as they began, they said I wasn't "clean" enough and stopped. After all the prep I had been through. I vowed never to do that again, nor have I in the 12 years since.
I did consent to a prostate biopsy, though, the doctor sticking this device up my ass that extracted 12 tissue samples right out of my prostate. That's how they discovered my cancer. And afterwards I had an implant of 65 radioactive seeds up my ass into my prostate.
But I still haven't had a colonoscopy, and I'm not ever gonna. And BTW, when I again refused to have one here at the Miami VA hospital a few years ago, it later turned out that veterans who had them at that exact same time were infected with HIV because of unsanitary procedures. My refusal likely saved me from getting HIV, and maybe saved my life.
So no colonoscopy for me, ever.