I had a neighbour with a stone when I was a teen - 15mm?
He went to the ER presenting with pain, he was tested for renal infection (uriculture.) Showed nothing. Then they did an ultrasound.
Then, they laid him in a big tub of blood-warm water and got a waterproof ultrasound transducer, and pulverised the stone.
He said the next time he peed, it sounded like a handful of sand being dropped in the bowl... Resolution of pain was damned near immediate when the pulverised the stone, but he said he did feel it pop! at first.