Are you talking about the IV? I just had surgery done two days ago and while the IV hurts a little, it wasn't awful. I have an extremely low pain tolerance, and if I can handle it, I'm sure you can, too!
My first operation was to undergo brain surgery. They ran one of these up to my brain to inject beads to block off a vein that was not supposed to be there. (AVM) You will be sedated but you may feel a little pressure. You'll be fine.