ESWL or Extracorporeal Shock wave Lithotripsy is a surgical procedure used in the treatment of kidney stones. Kidney stones are calcifications that form in the kidney (generally caused by an insufficient consumption of water or other dietary or metabolic factors). When stones attempt to move this can become very painful. If a stone becomes lodged in the kidney or ureter one way it can be treated is through a technique where the stone is broken up in to smaller pieces by sound waves to help you pass the stone more easily. This procedure does not require any incisions, but a machine is placed against your side sending hundreds of sound waves against the stone to fragment it.