THE EFFECT OF FAT AND NON-FAT COMPONENTS OF THE SKIN-TO-STONE DISTANCE ON SHOCKWAVE LITHOTRIPSY SUCCESS

Abstract

It is the nature of endoscopy to begin with diagnostic applications and then to progress with improvements in technology to therapeutic applications. Retrograde upper urinary tract endoscopy has similar origins. In regard to ureteroscopy, it began with Victor Marshall24 who first described in 1964 the use of a flexible fiberscope placed in the ureter to visualize an obstructing calculus. The therapeutic ureteroscopy of today is based on treating the stone burden by converting it to small passable fragments.4, 23 This progression in technology has continued with the development of new endoscopes and various forms of energy that can be used not only for lithotripsy but also to treat upper tract tumors and ureteral stricture disease.9, 21Current treatment of upper tract calculi is based on focusing shock waves onto a stone and fragmenting it into more easily passable pieces (i.e., Extracorporeal Shockwave Lithotripsy [ESWL]) or on direct endoscopic inspection and conversion of the stone burden into fine dust and small fragments with intracorporeal lithotripsy. Shock wave lithotriptors also have evolved, requiring less anesthesia, in part, because of smaller focal zones and lower delivered energy. With these changes, the indications for treatment have narrowed. Large stones, those associated with high-grade ureteral obstruction, and those for which fluoroscopic localization is difficult, are best treated endoscopically.6 If there is poor fragmentation noted with shock wave lithotripsy, conversion to endoscopic techniques also has a significantly higher success rate with minimal morbidity.19 There has been recent debate on whether most upper tract stones would be treated better in a retrograde endoscopic way, in which there is more certainty of proper fragmentation and clearance.The current treatment algorithm used for those patients with moderately sized, uncomplicated upper urinary tract calculi is based on ESWL monotherapy performed under intravenous sedation. All other stones would represent more complex presentations and should be treated endoscopically.18 If there is a greater anesthetic requirement than intravenous sedation for the shock wave treatment or if placement of a ureteral catheter is required to drain a completely obstructed upper urinary tract, the more definitive endoscopic treatment can be considered rather than pursuing shock wave lithotripsy.The techniques and instrumentation currently used for retrograde ureteroscopic lithotripsy are presented in this article. A large series of ureteroscopic treatments performed with current small-diameter endoscopes also are reviewed. A large, prospectively accrued database of upper urinary calculi treated ureteroscopically with the Holmium laser also is presented to highlight the techniques.