A Novel Needle Puncture Technique to the Renal Calyx using Laser-Assisted Ultrasound Scanning (LAUS) Method just before Percutaneous Nephrolithotomy: Preliminary Report

Abstract

Percutaneous entry is the initial and most important part of percutaneous nephrolithotomy (PNL). Needle puncture directly into the fornix of a calyx is the safest route of percutaneous entry into the renal collecting system. When the pelvicalyceal system is not dilated, localization and puncture of the specific calyx may require special expertise. Ho:YAG laser lithotripsy was performed to carve a channel to allow the ureteroscope to be passed into the desired calyx occupied with stone. At this point, percutaneous antegrade access to the calyx of interest was obtained using a 21-gauge nephrostomy needle under ultrasonic guidance with a biopsy attachment. Vapor bubbles and fragmented calculi were visualized as hyperechoic moving particles like powder snow in the aimed calyx on the B-mode gray-scale ultrasound monitor during laser firing. The needle was safely inserted into the desired calyx. This novel technique of needle puncture to the renal calyx using laser-assisted ultrasound scanning (LAUS) method is safe and effective, even when the pelvicalyceal system is not dilated. Greater experience and comparison to standard technique are required to determine if this method will be a useful technique in the future.