This is a prospective randomized controlled trial designed to assess the efficacy and safety of Lumenis® Pulse™ P120H holmium laser system with the Moses technology (holmium laser with pulse modulation) versus the Soltive™ SuperPulsed Laser System with the thulium fiber laser (thulium fiber laser), in dusting of renal stones during ureteroscopy with laser lithotripsy. 310 participants will be enrolled across 5 research sites.

This study will be a randomized clinical trial comparing ureteroscopy with laser lithotripsy with the Lumenis® Pulse™ P120H holmium laser system with the Moses technology (holmium laser with pulse modulation) versus the Soltive™ SuperPulsed Laser System with the thulium fiber laser technology (thulium fiber laser).

The primary objective is to compare the stone free rate as determined by computed tomography (CT) scan at two months (6-10 weeks) post operatively. A single urologist will evaluate all CT scans for residual stones and will be blinded to which laser was used during ureteroscopy.

The following information will be collected for research purposes as secondary outcomes: (1) stone treatment time (time from the start of lasing to the end of lasing; minutes); (2) total operative time (minutes); (3) lasing time (minutes, time the laser was in use, not including pedal pauses); (4) total energy used (kilojoules, kJ); (5) laser efficiency (mm per minute); (6) number of times the laser pedals are pressed (left, right, and total pedal presses); (7) laser fiber size; (8) stone analysis; (9) complications, and (10) patients' quality of life.

The results from the pre- and post-operative quality of life survey (WISQOL short form) will be obtained from the patient's medical record. A total of 3 clinic visits (i.e., the pre-operative visit and the stone surgery, one post-operative visit after 2 months of the surgery) will be needed for this study.

All visits are standard of care. Stone parameters (i.e. size, location, Hounsfield units, presence of hydronephrosis, stone volume, and composition), demographic information, co-morbidities, and post-operative parameters will be collected from the medical record in HealthLink.

The Thulium laser company is not involved in this research.

Inclusion Criteria:

• Patients with renal stones who require endoscopic laser treatment in the outpatient operating room. Patients may have an ureteropelvic junction (UPJ) stone if the treatment of the stone is completed in the kidney.
• Patients' stone size in a single renal unit of greater than or equal to 5 millimeters (mm) and less than or equal to 20 mm. Stone size is defined as the largest diameter of a single stone on pre-operative CT as assessed by the urologist. Patients with multiple stones will be included as long as their largest stone size falls within the above parameters.

Exclusion Criteria:

• Pregnant patients
• Patients with transplant kidneys or other anatomic variations: horseshoe kidney, pelvic kidney, ptotic kidney, urinary diversion or ureteral stricture
• Patients with irreversible coagulopathy
• Patients with known ureteral stricture disease
• Patient who do not have a pre-operative CT
• Non-English speaking patients and patients in other vulnerable groups such as lacking of decision-making capability, prisoner, or adult unable to consent
• Uric acid composition greater than 50 percent on pre operative stone analysis. Patients will be excluded post operatively if stone analysis from the time of surgery is greater than 50 percent uric acid.
• Prior ureteroscopy within 6 weeks of current surgery
• Urothelial tumor(s), direct extraction of the stone(s) without needing laser lithotripsy, and failure to reach the stone in the upper urinary tract with the ureteroscope
• Patients with only ureteral stones (ureteropelvic junction stones may be included as long as treated in the kidney)
• Patients with renal tubular acidosis or medullary sponge kidney

A single urologist will evaluate all CT scans for residual stones and will be blinded to which laser was used during ureteroscopy.