I too have actually been examined in that position for a real exam, several times in fact. Both times were because I was getting scoped. We tired it on my side first both times, but because of all the tight curves and twists in my lower colon, a ridged scope being passed when I am in a ball on my side was pretty painful. Being in knee/chest position allowed my innards to straiten out more so the scope could be passed as far as he needed to to go so he could see what he needed to see.
I know it seems funny maybe, but depending on the patients anatomy, sometimes having a patient in knee/chest position really is whats best for the patients pain and comfort level during the procedure, not necessarily for the total over all comfort level, meaning their embarrassment aspect of it. lol.
Well, you gotta do what you gotta do I guess, no?