National High Blood Pressure Education Program (NHBPEP) review paper on complications of shock wave lithotripsy for urinary calculi

Advances have been rapid in developing new techniques for removing urinary calculi (stones in the urinary tract); most stones can now be removed in a noninvasive or less invasive manner than open surgery. Many of these approaches use extracorporeal shock wave lithotripsy (ESWL), a method in which shock waves are focused on the stone while the patient is immersed in water. This article reviews results from studies of the effects from ESWL, including those that report adverse effects. ESWL, like open surgery, should only be used for stones that are causing symptoms, blocking or threatening to block the flow of urine, or that are a source of infection. The best results are obtained for stones two centimeters in size or smaller, located in the upper or middle segment of the ureter. Treating both kidneys at once may cause permanent impairment of kidney function; more studies of this issue are needed. Stones will form again in most patients unless the conditions that cause them are treated, and some problems, such as infection, elevated blood calcium or uric acid levels, or poor renal function, should be investigated at the time of ESWL. Patients with recurrent stones should undergo metabolic evaluation. Some kinds of stone (calcium oxalate monohydrate) are more resistant to ESWL than others (calcium oxalate dihydrate, uric acid). Acute complications of the procedure are mainly the result of the passage of stone fragments or of a large piece that will not pass. Although early evidence indicated no negative effects of shock waves, it now appears that cellular destruction can be caused by the high-energy waves. Results from animal studies are described. Acute (pooling of blood or fluid, enlargement of the kidney) and chronic (slightly impaired renal function, pancreatic inflammation) effects have been noted after ESWL, including an increased incidence of hypertension. Mortality for ESWL is approximately the same as that associated with the anesthetic used for the procedure. (Consumer Summary produced by Reliance Medical Information, Inc.)