Lithotripsy ESWL, or Extracorporeal Shockwave Lithotripsy, is the most common procedure used to treat kidney stones. It can be used for stones Â located in the kidney or upper ureters. The patient is positioned on a special table, given anesthesia, and then shockwaves from the machine are focused on the stone inside the kidney or ureters. The shock waves break the stones into small fragments that are then passed out through the urinary tract. Original versions of these machines had the patient placed in a bath of water to transmit the shockwaves. We use the newer versions of the machines where the bath has been downsized to a small water balloon placed against the patients back. The treatments usually take about an hour and are done as an outpatient.