Intrarenal lithotripsy with endoscopic retrograde ("retrograde intrarenal surgery", RIRS for Anglo-Saxon authors) is the last frontier in the treatment of kidney stones. Thanks to the progressive improvement of the endourologic instruments with the advances of digital technology, flexible endoscopes were developed that are able to offer a great quality of endoscopic vision. 


With the help of ureterorenoscopy, the flexible bladder is reached through the urethra, where the mouth of the ureter is located, which leads to the kidney. The kidney cavity is explored to identify the calculation that is pulverized using a Holmium laser. Some residual fragments may remain; however, the larger fragments will be removed with appropriate baskets, while the smaller ones will be expelled spontaneously. 


This procedure has several advantages: the absence of bleeding complications related to percutaneous lithotripsy, the absence of scarring and postoperative pain and a significant reduction of length of hospital stay as well as quick recovery and return to normal activities. By contrast, for calculations of dimensions greater than 2 cm, this method involves a lower percentage of successful treatment than the percutaneous lithotripsy. To get similar results to percutaneous treatment, in about 30% of the cases it is likely that a second procedure will be performed. 


The difficulties associated with reduced visibility of the operating field due to the smaller diameter, the flexible instruments, and the need to crush the calculation into very small fragments compatible with a spontaneous expulsion (1-2mm), impose a strict restriction to the indications of the RIRS calculations of a size not greater than 4 cm. Even this project involves general anaesthesia and a hospital stay (in uncomplicated cases, one night). In all cases it is necessary to place a double J ureteral stent (said second diction English "stents") for one week to protect the upper tract.