Extracorporeal Shockwave Lithotripsy

Excerpt

Renal stones pose a significant burden on the health care system. The prevalence of renal stones has increased from 3.8% in 1970 to 8.8% in 2010 in the United States, with annual healthcare costs of USD 3.8 billion. It is estimated that more than half a million people a year visit the emergency room for kidney stone problems. The most common presenting symptoms include hematuria, pain in the flank, groin, or abdomen.

There are many treatment modalities available for managing renal stones. They range from completely non-invasive outpatient procedures to invasive procedures requiring hospital admission and increased risks of complications. Extracorporeal shockwave lithotripsy (ESWL) is a truly non-invasive procedure as opposed to other surgical treatments used, such as retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL). The efficacy of ESWL lies in its ability to pulverize calculi in vivo into smaller segments, which are them expelled spontaneously by the boy. Shockwaves are generated and are then focused on a point within the body.

The shockwaves propagate through the body with minimal dissipation of energy (and therefore damage) due to minimal difference in density of the soft tissues. At the stone fluid interface, a relatively significant difference in density, combined with a large concentration of multiple shockwaves in a small area, produces a significant dissipation of energy. Through the different mechanisms, this energy can overcome the tensile strength of the stone resulting in fragmentation. Repetition of this process leads to the pulverization of the stone into small fragments that the body then can pass painlessly and spontaneously.