Primary study objective:

• To assess the current indications for URS and the treatment outcomes in terms of the stone free rate.

Secondary study objectives:

• To assess the peri-operative morbidity (30 days), including SAE, and translate them in the Clavien score.
• To define risk factors for the development of peri-operative morbidity after URS.

The following variables will be included to correlate in a logistic regression and uni/multivariate analysis:

• The use of antibiotics and incidence of infections
• The type of ureteral access used (balloon dilatation, access sheet) and the possible differences in morbidity.
• Specific medical conditions (age, BMI, DM, anticoagulants, cardiovascular disease) versus outcome and morbidity.
• The success of URS treatment following prior failed SWL.
• Outcomes in complicated cases (mono-kidney, renal congenital anomalies, neurogenic problems).
• To study preferences in intra-operative technique (device for fragmentation, use of ureteral stents, device to avoid intra-operative stone migration).
• To study differences between lower and higher volume sites.