In my life, I've rectal/prostate exams from real doctors or nurses in 3 different positions.
First, on my side on the table with my leg pulled up. Hated it. If a doctor or nurse wants to use that position, I always suggest something else.
Second, standing and bent over the exam table. This is probably the most frequently used position in my experience. Even with this though, there are some variations. You might be told to just bend over the side of the table, or bend over the end of the table, and rest your elbows on the table. Or, you might be told to rest your head and chest on the table, making the upper half of your body a little lower. Or, I've also been told to stand on the pull-out step at the end of the exam table, and then lean over the table. In this position, your ass is up higher than the front of your body. Usually they don't say anything about the position of your feet. But sometimes, they say to spread your legs apart slightly. Or some say to keep them closer together, and turn your feet inward slightly -- that I think spreads your cheeks apart better, or something like that.
Finally, I've been on the table on my hands and knees. My favorite position, simply because it's comfortable for me, and you feel totally exposed and more vulnerable. 😃 That has a couple of variations too that I've experienced. Sometimes it's literally on hands and knees, where you're supporting yourself with your hands. Other times, it's knees and lower the upper part of your body and support yourself on your elbows, rather than hands. And other times, it's on your knees, and lower your head and chest so they are resting on the table. That final position is the most exciting to me, because your ass, and only your ass, is up off the table and is ready to be examined.