I've had over fourteen since I was 18 and three in the past few weeks. Well I've had them longer but they have become a problem in the past few weeks.
Two on the right side and one on the left side. The big one on the right side was 12 millimeters. The other one on the right side was much smaller.
I had lithotripsy on both sides, two weeks apart. It is under general anesthesia and you won't know anything but you went to sleep. You won't be in a lot of pain or anything.
The bad thing though is they put a stent in on the right side from my kidney to my bladder to keep the passage open and keep the fragments from getting stuck and causing damage.
THAT is very uncomfortable and you can find more information here if your doctor plans one for you.
Ureteric Stent
It SUCKED for the first week and was very uncomfortable. The doctor removed it when they did the left side, again I was completely out and unaware of anything.
You feel it all the time. The second week was better as it seemed to settle in a bit but that first week was horrible.
On the upside they gave me LOTS of Lortabs. Which keep me awake at night so I didnt' really use many of them at all.
Lithotripsy is nothing to be afraid of, it is mainly pain free but you might feel a bit bruised afterwards and you will urinate blood and debris from the stones.
Pray they don't want to give you a stent though!