The only time I have ever been totally naked in a medical setting was at the age of fourteen when I was being admitted to the hospital. As I understand it, it's basic procedure in most hospitals that patients are always made to strip completely upon admission, and are given a brief glance-over by the attending nurse. That's how it was for me. Fortunately, the nurse in charge of my admittance was very understanding, and made it as easy an experience as possible.
I was brought into a room that had an examination table that was surrounded by a privacy curtain. The nurse told me to remove all of my clothing, and said she'd be back with a gown for me wear. She then left, pulling the privacy curtain closed. I got completely undressed, and sat up on the examination table. After a few minutes, the nurse returned with a gown for me. Her attitude the whole time was very matter-of-fact and supportive.