That person clearly has no idea about operations, the clinical team in them all wear hospital scrubs that are fresh sterile and clean when they enter the OR on top of that they then have a second layer that has been cleaned sterilised and sealed in a sterile pack that doesn't get opened untill it's needed. Some people need to stop watching staged hospital programs on TV and believing that's how real ones work!
There is good reason why patients are naked except for the sterile drapes and that is to cut the risks of infections from bacteria that could be on there clothing!
How can't you give consent for emergency catheterization when your under anesthesia?
I'd ask the doctor or the place the surgery will be done because the decision to prohibit underwear or panties could be more of the institution's policy than a hard-fast rule.
Sure there can be exceptions if the female is menstruating. No reputable person will say, "you have to use a tampon because it's your time of the month."
Being naked on operating room table, while unconscious, with all sorts of people walking in and out with no regard to you as a human being, that annoys me. It’s as though you are a nothing. Leaving you exposed without a care in the world, regarding how long or who sees. Even the janitor can come in to get the trash. How is he sterile? Give me a break,