Prospective Multi-center Study Comparing Pulsed Tm:YAG Laser to Pulse Modulated Holmium Laser in the Treatment of Nephrolithiasis With FANS Access Sheaths

Inclusion Criteria: * Solitary renal stone 7 to 20 mm in size or in the case of multiple stones the conglomerate diameter (additive maximal diameter of all stones on axial imaging of computed tomography) of 7-20 mm is required * Must be a suitable operative candidate for flexible ureteroscopy per American Urological Association guidelines * Must be 18 years or older * Must be able to give consent * Bilateral ureteroscopy will be permitted , but only the side(s) where the FANS access sheath was used (per surgeon discretion) will be included in the study, however can include both sides as separate units. Subjects will be enrolled only once in the study. No subject will be enrolled more than a single time. For patients undergoing bilateral ureteroscopy, each kidney will be considered a separate unit for stone-related assessments. Peri-patient measures, such as operative time, will be recorded at the patient level. Bilateral cases will be clearly identified and handled consistently to ensure accurate and appropriate interpretation of study outcomes. * Must be a patient of one of the surgeons participating in this study. Exclusion Criteria: * Concomitant stones in the ureter * Prior radiotherapy to the abdomen or pelvis * Neurogenic bladder or spinal cord injury * Pregnancy * Untreated urinary tract infection (UTI) * Anatomical abnormalities (including, but not limited to, bifid system, pelvic kidney, horseshoe kidney) * Prior ipsilateral upper urinary tract reconstructive procedures or history of ipsilateral ureteral stricture