Key study team members working on the study are leaving the institution.

The purpose of this research study is to compare how well two treatments work for removing kidney stones. The two study groups include ureteroscopy with long/short pulse lithotripsy to remove kidney stones. Both of these options are considered standard of care and are used currently in surgery.

This study will compare two types of laser lithotripsy to see the pulse duration to determine which settings are more effective. This is a randomized control trial with subjects randomized to either long pulse or a short pulse group. Those subjects with a single kidney/ureter stone measuring up to 20 mm will be eligible for the study. The procedures will be performed using the standard of care instruments and techniques but the pulse type setting in surgery will be constant. Some Holmium laser devices provide the option to modulate the pulse duration. A longer laser pulse duration (700 μs or 1500 μs) as compared to a traditional pulse duration (300 μs or 350 μs) has been demonstrated in vitro studies to provide effective stone disintegration while reducing laser fiber tip degradation and stone retropulsion. Both the long and the short setting can dust the stone and currently we alternate in each procedure from one setting to the other and it is unclear which setting is more effective. No changes to operative technique will be performed for subjects in the study vs regular patients undergoing the same procedure. All subjects will be seen one week to one month after surgery for stent removal and follow up.

Inclusion Criteria:

• Kidney/ureter single stone between up to 2 cm
• Age over 18 years
• Two kidneys

Exclusion Criteria:

• Solitary Kidney
• Age under 18
• Pregnancy