Oh horsepuckies! Yes, the prep is the worse part of the procedure. Especially if you've got some gastro who insists on overdoing the prep. If you do the prep correctly, which means drinking LOTS of FLUIDS, not just the prep yech itself, that is sufficient unless perhaps you are one who is constipated a lot. Once you are running clear, no sand, no bits and pieces, just clear, maybe slightly yellow liquid you are squeaky clean. The other key besides the LOTS of liquids is the timing. A prep timed for EARLY morning scope, isn't QUITE as effective if the scope isn't until LATE morning or noon.
And horsepuckies to air being the principal cause of pain. The primary cause of pain during colonoscopy is the scopist. It takes TIME to do a pain free scope. That flexible scope shaft often loops back on itself (try running a thick string or cord thru a horizontal straw from end to end). The looped scope shaft stretches the colon width-wise and that causes the pain. Too much insuflated air is the second most common cause of pain during the scope and again it is the stretching width-wise of the colon and both are due to the scopist not taking enough TIME. The "wider" the colon due to the air insuflation the easier and faster the scope can be passed thru. The faster one tries to advance the scope the more likely the looping of the shaft and the more looping that occurs before the scopest stops to pull the scope back a bit and proceeds again. Real time imaging during a colonoscopy has proven this.
Colonoscopy does tend to be more uncomfortable in women, NOT because of the "extra organs" but because they tend to have a slightly longer and more flexible transverse colon. That baby can drop down almost to or to the pubic area!!!!
I've posted the URLs several times thru the years to two med journal abstracts from which I gained this information (and my own experience bears it out). I'm female, have most of my scopes done w/o sedation, just a little Demeral, and the ONLY area of discomfort my gastro and I have encountered is my transverse colon and my ICV area where I have narrowing and some malformation (not due to surgery, my resection was of the mid-ileum and the ICV is still intact). The ICV is a difficult area to penetrate w/the scope and there is a percentage of scopes in perfectly healthy individuals where the ICV can't be penetrated by the scope.
Some people are like Slinkies... Not really good for anything, but they still bring a smile to your face when you push them down a flight of stairs.