Surgical technique
All patients provided written informed consent before the surgery. As a standard procedure, pre-surgical urine cultures were obtained and positive cultures were treated according to antibiogram. Second-generation cephalosporins were utilized for preoperative antibiotic prophylaxis. All of the surgeries were performed under general anaesthesia. After the cystoscopic evaluation of the bladder, a retrograde pyelography was performed to evaluate the upper urinary system. A 0.035-inch safety guidewire (Sensor®, Boston Scientific, Marlborough, MA, USA) was routinely placed. Then, the ureteral access sheath (UAS; 10-12 Fr. Bi-Flex™, Rocamed, Monaco or 11/13 Fr. Boston Scientific, Marlborough, MA, USA) was inserted over the working guidewire and placed just below the proximal ureter stone under fluoroscopic guidance. The flexible ureteroscope (MARKA) was inserted through the UAS, and a holmium: YAG laser with a 272 μm laser fibre was used to fragment the stones. The laser energy and pulse frequency were varied based on the stone burden, stone density and the surgeon’s preference. Stone fragments >2 mm were extracted using a nitinol basket catheter (Dakota®, Boston Scientific, Marlborough, MA, USA). A 4.7 Fr. double J stent was inserted into the urinary system and left in place for 1 to 4 weeks according to the surgeon’s preference. During follow-up, all patients were evaluated using kidney-ureter-bladder radiography at the postoperative first day and low-dose CT in the postoperative first month.