I'm a nurse and work in a high dependency for post surgery. We are used to everything, periods are natural and have patients come on their period quite often from the stress of surgery. Do not worry you are not disgusting and noone would even think that. However I would check with them when you arrive because they may not want you to wear a tampon due to how close it all is. Try not to worry.
@Nikki thank you this is very reassuring. I am actually a nurse too but not in surgery so wasn't sure what would be okay. Xx
You wear a pad and knickers for surgery, and then naked under your gown. I had a surgery, years ago and was given this advice from the hospital. You can double check with them, as it could've changed since then