This prospective observational study aims to evaluate the association between anesthesia type and surgeon-perceived workload and surgical ergonomics in adult patients undergoing flexible ureteroscopy and retrograde intrarenal surgery (RIRS) for kidney stones. Patients will be classified according to the anesthesia administered during routine clinical care as general anesthesia or spinal anesthesia. The choice of anesthesia will be determined by routine clinical practice and the anesthesiology team and will not be assigned by the study protocol. Surgeon workload will be assessed immediately after surgery using the Surgery Task Load Index (SURG-TLX). Perioperative outcomes, including operative time, procedural characteristics, postoperative pain, complications, and stone-free status, will also be evaluated.