Is there a role for prophylactic shock wave lithotripsy for asymptomatic calyceal stones?

PURPOSE OF REVIEW: The tolerability of extracorporeal shock wave lithotripsy has led to an increase in the treatment of small, asymptomatic renal calculi, yet we know very little about the natural history of such stones or about the long-term effects of this treatment. The efficacy of extracorporeal shock wave lithotripsy has been called into question, especially for lower pole stones. Several recent clinical studies have addressed these issues as well as the natural history of residual stone fragments following extracorporeal shock wave lithotripsy.

RECENT FINDINGS: Preliminary results of a randomized controlled trial show that prophylactic extracorporeal shock wave lithotripsy for small, asymptomatic renal calyceal stones does not appear to offer any advantage to patients in terms of stone-free rates, quality of life, renal function, symptoms, or hospital admissions, nor does it appear to affect blood pressure. However, a policy of observation is associated with a greater risk of requiring more invasive procedures. Reports regarding the incidence of hypertension following extracorporeal shock wave lithotripsy are conflicting, as are reports regarding anatomical factors affecting the clearance of lower pole stones. Percutaneous removal appears to be superior to extracorporeal shock wave lithotripsy for the treatment of lower pole stones.

SUMMARY: Extracorporeal shock wave lithotripsy does not appear to improve the clinical outcome of patients with small, asymptomatic calyceal calculi. Longer follow-up is required to assess the validity of the preliminary findings and may shed light on the long-term effects of this technique on blood pressure and stone growth/recurrence. Anatomical factors affecting the clearance of lower pole stones require standardization and further study. Further in-vitro studies are required to study the kinetics of stone growth and the effects of urine composition, flow rate, and macromolecular components.