Will the surgeon knock me out to drain my seroma from my hernia repair?

We don't usually use general anesthesia to drain a seroma. Having said that, it depends on how big the seroma is, where it is, and how the surgeon plans on draining it. Most seromas are drained with a needle with or without drain placement. We may use some local anesthetic, but not usually general anesthesia.

most providers do not sedate a patient for a seroma drainage that is done thru the skin; usually a needle is used to access and remove the fluid. most providers would use local anesthetic, like lidocaine or similar medication. however if a patient is particularly anxious, then sometimes some sedation can be provided; but again thats not the common approach otherwise.