Your surgical team maintains a sterile field during your surgical procedure. They will wear a mask over their mouth and nose, some may wear a full hood that covers their head, many will wear a sterile gown and sterile gloves. Disposable supplies are sterilized by the manufacturer while reusable instruments are sterilized before each use.
If any sterile item comes in contact with an item that is not sterilized and anyone in your surgical team notices this, they will inform the others immediately; it is called surgical conscience. That item is then removed from the sterile field, re-sterilized or replaced, if needed.