Years ago I had a couple of "sigmoidoscopies" (lower regions only). All seemed fine. Then got under a good health plan (KaiserPermanente) and did the standard "send in your sample" bit a couple of times. Finally, several years ago, they called me to schedule a full colonoscopy.... 2 days of drinking stuff to clean me out "from the top down" rather than "from the bottom up", then to their team for the procedure.
It was explained that "it would be pretty uncomfortable during the procedure, but that I wouldn't remember it afterwards.(some sort of new drug).... It was also explained that IF they see anything suspicious, they would take small 'snips' for biopsy.
Well, the memory thing worked fine... I had no memory of the actual procedure. They did snip several 'interesting' spots for examination, and gave me actual pictures of the offending spots.... which turned out to be only 'possible future concerns'. I thought I was home free........ then next day, near bedtime, I used the toilet and found blood! Off the the emergency room in the middle of the night!
"Hmmmm... they said," We'd better monitor this. You will probably need to be admitted." and thus began the longest night I ever spent, lying on a gurney in the emergency room, hooked up to an IV drip and needing to pass a buildup now & then.....except that it was a quiet night in the E.R., and they mostly didn't check on me....except for early on, one young man, probably practicing writing a paper on "degrees of pain", who decided to "do a rectal" to see IF I actually had a problem. He put on a glove, and I'm sure no lubricant, inserted his finger in a manner which left me gasping with discomfort. "Yes," he said definitively, "there's blood there, all right." After him, they just ignored me until morning. Turned out they couldn't find a room for me until shift change when the day staff could do it!
   So.... I was taken up to a room, where I was given a bedpan and passed enough blood clot to pique their interest. I was then sent to a specialist in some deep basement labyrinth where they had me drink radioactive stuff and lie VERY still for an hour while a huge machine hummed and took pictures of my nether regions from every possible angle. (the technician actually played classical music.. a string quartet... to pass the time)
   Back to my room, I was given a sleeping pill for my 2nd night, but was waked twice for blood transfusions! Yes, there HAD been "blood there all right"
    Finally, late afternoon on the 2nd day, they decided I had stopped bleeding and was allowed to go home.... but after calling my wife to come get me, I waited for the required wheelchair person to take me to the lobby... and waited... and waited... Finally, I wandered down the hall till I found a nurse who put in a call to 'patient services', and I got out of there!
    When first scheduled for the colonoscopy, they said the if there were NO problems, I'd not have to do it again, but if they found 'items of concern', I'd be asked to repeat it "in a few years".
    IF they call, I'll say, "Sorry, I can't afford it." They will say, "There's no charge for the procedure... it's covered in your health plan." I will reply, "You cost me 2 days of prep, 2½ days in the hospital, 2 days to get back to semi-normal, all of which meant loss of work time... and a $250 bill for the hospital stay!"

   I **think** that if they want to do this again (soon now, I'd suppose) I will ask for a written promise to NOT do any snipping and merely inform me if there are any 'areas of interest'... and we will discuss my options!