Most often when you have a kidney stone that can be zapped with lithotripsy, the stone is usually turned into sand so you do not feel it when you pass all the tiny particles. Now even though that is the norm, there are some people like myself whose pieces do not break up into sand, but they do break up into smaller pieces. Depending on the size of the original stone this can be uncomfortable. Mine do not break up well so if I am having Lithotripsy, I am usually admitted for the next few days as I pass the pieces so my pain can be managed. I unfortunately get tons of stones and I have a huge one now that is going to need either litho or surgery. You have to be careful if you have a lot of lithotripsies as they can hurt your kidney, but that is after having a lot of them. My last bout I had 14 stones between the two kidneys.
But for most people it's an outpatient procedure you wake up with no pain and a tiny bruise where they zapped you. It's no longer done in a tub of water but on a table. So you should not worry too much.