Comparison of Suction and Conventional Ureteral Access Sheaths in Kidney Stone Surgery

The goal of this observational study is to compare conventional and suction (aspiration) ureteral access sheaths used during retrograde intrarenal surgery (RIRS) in adults with kidney stones. The main questions it aims to answer are: * Does the use of a suction ureteral access sheath increase the stone-free rate compared with a conventional sheath? * Does the use of a suction sheath reduce operative time and complications such as postoperative fever and infection? Researchers will compare patients treated with a conventional ureteral access sheath with patients treated with a suction ureteral access sheath during routine RIRS. Participants will: * Undergo RIRS for kidney stones as part of their routine clinical care * Have their surgical data recorded, including operative time and any complications * Attend routine follow-up visits, including imaging to assess whether stones remain