They will always ask you if you are on any medications before you have surgery and it's up to you if you want to lie. Not like test, winny, etc will matter but they will still ask you.
If they are putting you under, they should definitely draw blood.
Anesthesia's can cause reactions to the body if you have certain chems in your blood.
They will probably only test for standard things and might see if your liver is off.
That's what happened to the person I know. The doctor didn't find test, deca and dbol. He found that his liver was all out of sync.