One thing you could try and do is turn it around. If you spent all day long checking men for hernias (the turn your head and cough routine), do you imagine that would change the way that you would look at a lover? I suspect it wouldn't. And that doesn't mean the allure of the mere object won't diminish. If he were to see you nude I wouldn't expect his eyes to pop out of his head. At least not by the mere object. It doesn't mean he won't be excited by being shown, or be excited by what, as lovers, you are about to do.
Plus, it isn't like we are ever, in most cases, entering into an intimacy with someone who has never seen bodies before. There can always be some anxiety about measuring up. And I would imagine that former partners' bodies are always going to be at the top of the list compared to bodies that are seen in a clinical, medical setting, so ultimately you are probably measuring up to the same favorite-bodies-he-has-ever-seen regardless of him being a gynecologist or not.
And for the most part, current lovers tell each other they are the most beautiful they've ever seen. It may not, in a pure object sense, always be true, but it usually is true because bodies aren't just beautiful for what they are, they are beautiful for what they do, and how we feel about them.
The one thing I can say with some certainty is that it is generally a bad idea to proceed, or not proceed, in a relationship based upon what you imagine is taking place, or not taking place, in someone's head. Why not just talk to him about it, or put it to the test. Invite him over and do a Sharon Stone Basic Instinct scene for him and see if he gulps.