A mate of mine had kidney stones 5 years ago and had to go through a Ureteroscopic Stone Removal procedure.
"Stones located lower in the collecting system (closer to the bladder) may be removed by a basket extraction technique. A probe is inserted through the urethra and bladder into the ureter. Using direct visualization of a fiberoptic scope, the stone is grabbed and surrounded by a clasp or expandable cage (basket) and manipulated through the probe. The entire probe is removed dragging the stone out with the probe. Recovery is usually within several days. As with the ESWL, a stent is sometimes left in place in the ureter for several days to allow healing. Not all stones are located in areas where this technique is practical."