We carried out studies using an ureterorenoscope in 14 cases, including 13 patients suffering from an ureteral stone. The stone was smaller than 1 cm and existed in lower and middle portion. The other patient had a foreign substance, which was a double J-stent catheter that had been passed into the middle portion of the ureter accidentally. Initially, the size and course of ureter, the position of stone and foreign substance were ascertained using a retrograde pyelogram. The patients were placed in a lithotomy position under spinal anesthesia or epidural anesthesia. The ureterorenoscope was inserted into the bladder through urethra and the instrument was further extended through ureteral orifice and ureteral lumen to the position of the calculus or foreign substance while observing the procedure. Once the calculus or foreign substance was observed, a 4F Pfister-Schwartz stone retriever or forceps was inserted through working channel. After coming in contact with the stone or foreign substance, the matter was removed while observing it with the scope. The foreign substance and 77% of the stones observed were removed by this procedure and the usefulness of the ureterorenoscope was successfully demonstrated in the cases. However, on the other hand, of these 14 cases, 2 (14%) experienced ureteral injury. In one case, the ureter was penetrated by the scope; and in another, injury occurred during the biopsy of the ureteral wall. Therefore, it is our opinion that more careful use of the ureterorenoscope is necessary to prevent these types of injuries
