Extracorporeal shock-wave lithotripsy (ESWL) causes disintegration of renal and biliary stones (see CALCULI) without physical contact, and is therefore an attractive procedure for patients and surgeons alike.

Shock waves generated outside the body can be accurately focused with a reflector whilst the patient is suspended in water, to facilitate transmission of the waves. These are focused on the calculus. The resultant fine fragments are passed spontaneously in the urine with minimal, if any, discomfort. The procedure has been shown to be safe, short and effective, and is most acceptable to patients.