Holmium laser is the current gold standard for lithotripsy on urinary lithiasis, while Thulium is brand new. The latter has been released in July 2020 in Europe, and only in-vitro studies have been published.

The aim of this study is to compare the stone free rate in ureteroscopy, for all consecutive patients treated with laser fragmentation, between both Holmium and Thulium lasers.

The costs and complications will also be studied.

Inclusion Criteria:

• renal ou ureteral stone confirmed by an abdominal and pelvic computed tomography
• treatment with rigid or flexible ureteroscopy
• laser lithotripsy during the procedure
• bacteriological examination of urine (sterile, bacterial colonization or treated by antibiotics)

Exclusion Criteria:

• non-use of laser for stone lithotripsy
• pregnant women
• under 18 years old
• refusal to give informed consent
• urinary malformation

Patients who are scheduled for ureteroscopy on renal or ureteral stones, which have been previously confirmed by tomography