It’s normal to be concerned before a surgery and getting blood can understandably add to anxiety about the procedure.  Fortunately, the risk of getting HIV from a blood transfusion, at least in the United States, is extremely low.  There is a rigorous self-selection and then testing process for all donations that make it almost 100% safe.  To put it in context, you will be at much, much greater risk of having an accident on the way to the surgery then getting HIV from the surgery. Good luck!