I had MAC anesthesia too. As Paul says it's basically like general anesthesia without the tubes. An anesthesiologist monitors you the entire time and adjusts your level of sedation as needed, but for all intents and purposes, you're out ice cold from propofol :)
As for what I wish I'd known before surgery, I'd say the following off the top of my head:
1. That I needed to do an enema just before the procedure. I wish I'd known this for mental preparation purposes :) Sucks to spend all your time worrying about things that you know will happen, and then minutes before showtime, to get presented with a long plastic tube that you're supposed to stick up your butt so you can forcibly evacuate your bowels. That one caught me by surprise for sure.
2. That ummm "brown things" could slip out of my numb butt immediately after surgery. Found this one out the hard way with a "splat" when exiting the car upon arrival at home afterward. On the plus side it did create a very memorable moment for my wife and I to share well in the future though
So yeah, wear black pants to the hospital or surgery center if you can!
3. That there would be a frat party in my butt for the days/weeks after surgery. I felt all kinds of weird sensations, ranging from the expected post-operative pain to simply random stinging sensations that just came and went. Not all were painful (although some were), they were just unforeseen more than anything else.
4. That the recovery timeline varies A LOT. Some people are back on their feet and largely okay in less days than you can count on one hand. Other people, like me, get stuck being rather useless for a month or more. It's hard to say what your case will be ahead of time, but just don't be surprised if you recover much quicker or much slower than expected.
5. That keeping the area clean is of
utmost importance. If the surgeon tells you to take four 20-minute soaks a day after surgery, DO IT! Don't skimp here. I developed an infection after LIS which required a second surgery to cut open and drain. Not fun. This is a relatively rare complication, and in some cases it frankly can't be avoided, but in most cases, thorough cleansing will keep it from happening.
6. That painkillers are your friend. Everyone with butt problems is afraid of being constipated from opiate painkillers. And some people don't even need opiate painkillers after LIS. But if you do need them, take them. Don't be shy. A good stool softener should overcome any constipation they cause, and either way it's better than suffering through any post-operative pain.
I think that's all the blabbing I can think of for now. Personally I think the fact that recovery timelines vary a lot is the main one to keep in kind. I took forever to recover and kept wondering what the heck was going on. After being on this board for a while, though, I can say that recovery differs so wildly between individuals that I'd be hard pressed to pin down an exact estimate other than saying it's "a few weeks" in most cases.