flexible ureteroscopy is used to removed the stone. If a double-J stent was inserted pre-operatively, it was removed at the beginning of surgery. Rigid ureteroscopy was routinely used for ureteral dilatation before fURS. A 0.035 mm guidewire was advanced through the urethral and ureteral meatuses to the renal pelvis under direct rigid ureteroscope vision. A 14-Fr ureteral access sheath (Cook Medical, Bloomington, IN) was then passed over the wire to the ureteropelvic junction, and 7.5-Fr fURS (Flex-X2, Karl Storz, Germany) was performed through the sheath. Intrarenal pressure was stabilized by a pressure-sensitive pump (Shenda Medical, China). Holmium: yttrium-aluminum-garnet laser was used to fragment the stones. After lithotripsy, 6-Fr double-J stent was routinely inserted in all cases for 2-4 weeks.

sepsis is defined as the concurrence of infection and at least 2 of the following 4 criteria: (1) body temperature >38°C, (2) heart rate >90/minute, (3) respiratory rate >20/minute, and (4) leukocyte count <4,000 cells/μL or >12,000 cells/μL