Flexible ureteroscopes, also called flexible ureterorenoscopes, are used not only to diagnose diseases within the kidney and ureter, but also for the treatment of certain diseases within the kidney and ureter. The soft ureterorenoscope is slim and soft with a diameter of 2mm, which is extremely easy to pass through the ureter via the urethra and reach the kidney directly. The head end of the mirror can be bent up/down 270 degrees under the operator’s control, which can observe and deal with the renal pelvis and calyces that cannot be reached by the ureteral rigidoscope, and at the same time, it can solve the shortcoming that the traditional ureteral rigidoscope can only look forward and cannot see the renal calyces that are not directly in front of the kidney. Therefore, with ureteral flexible scope, it is possible to see all corners of the kidney more comprehensively, and at the same time, in combination with Holmium laser, it is possible to perform lithotripsy of the kidney and the high ureteral superior segment. Some patients do not understand, isn’t the upper ureter straight? Why do we need a soft ureteroscope too? The reason is that during lithotripsy, it is difficult to avoid small fragments being washed into the kidney, so if the stone removal rate is to be guaranteed, it is more effective to use a flexible ureteroscope. Of course, ureteroscopy also has its limitations. In fact, there are limitations to any procedure, including ureteroscopy. The limitations of ureteroscopy: 1. The ureteroscope can be bent at will only at the head end, so for those patients whose ureter is excessively bent or even looped, the ureteroscope may not be put in smoothly. 2, the ureteroscope itself is thin and easily damaged, so the laser power equipped cannot be too large, so the efficiency of lithotripsy is naturally limited. Therefore, the most suitable size of stones for ureteroscope is about 2cm in diameter or patients who have failed extracorporeal shock wave lithotripsy although the stones are not large. For patients with large stones, the procedure can take too long and be dangerous, and the stone fragments can easily cause “stone streets” during stone removal. For larger kidney stones, the most suitable method is percutaneous nephrolithotomy, but percutaneous nephrolithotomy makes a hole in the kidney and patients need to risk hemorrhage (1-3% probability). Of course, if the patient’s financial situation is good, although the stones are relatively large, as long as the patient is willing to spend more money, he can also remove the stones through multiple ureteral flexible surgery, after all, the ureteral flexible microscopy avoids the risk of bleeding.