I had major ear surgery yesterday at one of the most prestigous hospitals in Boston. I smoked bowls the night before. Went in to the hospital the next morning. When the nurse was checking me in, she asked if I use cocaine or marijuana and I told her, "marijuana

- yes" (it's not good to lie to your doctors). She said, "hmm about how long ago was the last time?" I told her, "Probably about a week", just to be safe from having to get rescheduled. Her response was, "Oh yeah that's fine, as long as it wasn't this morning." I laughed and told her not to worry, that I wasn't high. LOL.
So to me, that means that they don't care if you smoke before the surgery, as long as you're not high DURING the surgery. Personally, it didn't have ANY negative effects towards the anestesia or anything else, for that matter. I also smoked the night I came home, and will continue to as it works much better for healing my pain than the 5mg Percocets they prescribed me.
It really is a miracle drug. Don't start thinking it's going to be any worse for you just because you're seeing a doctor that doesn't "reccomend" it. Unless you're having lung or throat surgery, of course, that would just be silly.