Electronmicroscopic Evaluation of Urinary Stones Following Laser Stone Disintegration in Patients

Abstract

Intracorporeal laser-induced Shockwave lithotripsy(LISL)with a high-intensity Nd-YAG laser has proved to be an effective and secure procedure for the treatment of ureteral calculi.Especially bigger,obstructing stones can be completely fragmented into very tiny particles or stone powder.The fragments are flushed out through the endoscope during laser treatment, so that the patient is free of stones immediately following the operation.A high intensity Nd-YAG laser with nanosecond pulses can generate a Shockwave in a liquid suurounding a stone. Shock waves reaching an area withdif ferent sound wave impedance-e. g. urinary calculi-are partly reflected.At the front of the calculus compressive and at the rear tensile pressure is generated with consecutive disintegration of the stone.The laser beam is coupled into small,highly flexible quartz fibres(0.2,0.4 and 0.6mm core diameter). The laser energy is focussed at the fibre tip by a specially shaped end. During laser application,the laser-induced breakdown(LIB) can be seen as a light cone beginning at the fibre tip.Stone disintegration can be done within the LIB.Optimal fragmentation can be heard as a series of slight clicking sounds. (1,2).