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 crushed by an ultrasound probe or evaporated by a laser probe or grabbed by small forceps, etc.
The advantages of RIRS over open surgery include a quicker solution of the problem, the elimination of prolonged pain after surgery, and much faster recovery.