Just been though the painful process of having a stone diagnosed in one of the kidneys.
The painful part is the stone telling you its there. CT scan showed a 8mm x 6mm stone "trying" to pass through the
Had a stent inserted into the ureter to open it to 5 mm and the urologist hope that with a magic pill which may dissolve the stone to allow it to pass through the stent.
He said that they work on the thesis of multiples of ten.
If you have a stone that is 2mm take that number away from 10 (2 from 10=8) you have an 80% chance of passing it naturally.
An 8mm stone gives you a 20% chance of passing it which he halved again for some reason I forget he said in my case.
He's giving it a month and then may blast with laser or ultrasound, the stent being there to help pass the fragments.
He said that 40% of stones if left a month will be passed without the patient knowing it,may be lucky to hear a ping in the toilet bowl.
My chances look slim though.