RIRS stands for Retrograde IntraRenal Surgery. It's a minimally invasive procedure used to treat kidney stones and other conditions of the urinary system. During RIRS, a small scope is inserted through the urethra and guided up into the kidney. This allows the surgeon to visualize the kidney and surrounding structures, and then remove or break up kidney stones using specialized instruments. RIRS is preferred for smaller kidney stones or stones located in the kidney's inner regions, as it typically offers quicker recovery times and fewer complications compared to traditional surgery.