Extracorporeal shock wave lithotripsy (ESWL) has had a dramatic effect on the management of urinary stones. Which of the following statement(s) are true concerning shock wave lithotripsy of urinary stones?

a. The basic principle of lithotripsy involves the generation of shock waves which are focused fluoroscopically on the calculus and are delivered to the patient who is submersed in a water bath

b. The most common complication after lithotripsy is ureteral obstruction secondary to stone fragments

c. ESWL can be associated with stone-free rates ranging between 60%-95% at six months for renal and proximal ureteral stones

d. The combination of ESWL with percutaneous nephrolithotripsy improves the results for stone clearance in patients with large or branched stones such as staghorn calculi 

The introduction of ESWL has virtually eliminated open surgery for renal and ureteral lithiasis. The basic principles of all lithotriptors include shock wave generation, focusing of the sound wave, and imaging of the stone. All lithotriptors produce shock waves by a spark gap electrode or by a piezoelectric or electromagnetic element. The wave is then focused towards the stone which is localized either employing fluoroscopy or ultrasonography. The patients are either submersed in a water bath or “coupled” by a water cushion. The acoustic density of water and body tissues is essentially the same. Therefore, there is little or no impedance of the shock wave at the water-body interface. Upon striking the stone, which is of different acoustical density, the shock wave undergoes reflection and refraction, resulting in compressive and tensile forces which fragment the stone.

Complications of ESWL are rare. The most common complication after ESWL is ureteral obstruction secondary to stone fragments requiring either additional ESWL, urethroscopic stone retrieval or stent placement. ESWL is the treatment choice for the vast majority of renal and proximal ureteral stones with stone-free rates ranging from 60%–95% at six months. Stones larger than 3 cm and branch stones such as staghorn calculi are best treated with percutaneous nephrolithotripsy alone or in combination with ESWL. The combination of extracorporeal and percutaneous techniques can result in average dome clearance rates in excess of 80%.