EXTRA-CORPOREAL SHOCK WAVE LITHOTRIPSY (ESWL)

Introduction: The advent of lithotripsy began a new era in therapy for urinary calculus disease. Shock waves are characterized by a high pressure front consisting of multiple, nonlinear low frequency waves that have a rapid initial rise and a gradual decay. When the shock wave encounters the stone, part of the energy is reflected back at the source, part is absorbed, and rest is transmitted through the stone. A resulting compressive force is created on the front surface of the stone. Other forces that destruct the stones are called spalling and cavitation. Lithotriptors are characterized by type of shock wave generator, method of shock wave focusing, shock wave coupling and imaging techniques. Lithotriptors have undergone quite an evolution since 1984. The original unmodified HM3 is classified as the first generation lithotriptor. The second generation lithotriptors are characterized by the use of electromagnetic and piezoelectric sources. Third generation lithotriptors have the advantages of being smaller and mobile. Today, ESWL has a firm hold as the primary therapy for stones in the upper ureter, renal pelvis, upper and middle calyces of the kidney. In the climate of managed care, the cost effectiveness of the elected treatment is very important.