Retrograde intrarenal surgery (RIRS) is a procedure for doing surgery within the kidney using a viewing tube called a fiberoptic endoscope. In RIRS the scope is placed through the urethra (the urinary opening) into the bladder and then through the ureter into the urine-collecting part of the kidney. The scope thus is moved retrograde (up the urinary tract system) to within the kidney (intrarenal). RIRS may be done to remove a stone. The stone is seen through the scope and can then be manipulated or evaporated by a laser probe or grabbed by small forceps.