Holmium laser lithotripsy of urinary calculi: Initial experience with the 200 micron holmium laser fiber

We performed a pilot evaluation of the 200 micron holmium laser fiber to treat a variety of ureteral and renal calculi. The 200 micron laser fiber has the potential advantage of being more malleable and therefore having increased deflectablity compared to larger laser fibers. A total of sixty patients underwent treatment for urinary calculi either primarily or as an adjunct. Thirty-three intrarenal stones and 26 ureteral stones were ureteroscopically treated with the 200 micron holmium laser fiber. Mean stone burden was 12.8 mm for renal stones (range = 3-40 mm) and 7.7 mm for ureteral stones (range 5-15 mm). The ability to treat calculi in dependent calices and energy required to fragment calculi were studied. In addition, a bench top study was performed to determine the effect of the 200 micron fiber on active deflection of various flexible ureteroscopes. The bench studies revealed that the 200 micron fiber limited the flexibility of the ureteroscopes from 9 to 43 degrees depending on the ureteroscope. In spite of the limitation demonstrated in the bench top studies, in vivo we found that using the small diameter laser fiber, we could access and treat calculi located within dependent and lower pole calices. In addition, although the 200 micron fiber did inhibit deflection of flexible ureteroscopes, in all cases we were able to obtain access to the lower pole using this fiber.