Surgical technique
Written informed consent was obtained from all the patients. A retrograde pyelography was performed in all patients to control the entire renal collecting system. A 0.035-inch safety guidewire was placed.
In group 1 (sURS group), a second hydrophilic guidewire was carried out into the ureteral orifice through the sURS’s (8f or 9f Fr, Karl Storz, Rietheim-Weilheim, Germany) working channel. A semirigid ureteroscope was gently passaged between these two guidewires (“railroad” technique) [10]. The optical ureteral dilatation was done with sURS, and the entire ureter was assessed for anatomy, additional pathologies, and calibration of the ureter. Then, a UAS of an appropriate diameter was placed just below the ureteropelvic junction for renal stones and just below the stone for upper ureteral stones under fluoroscopic guidance.
In group 2 (non-sURS group), the UAS was inserted directly by gliding over the working guidewire. First, a 10-12 f or a 11-13 f UAS was tried. If these sizes were unable to pass to the collecting system, or there was stenosis in the ureter during sURS (for group 1), a smaller UAS was tried under fluoroscopic control. If all attempts failed, insertion of a bare flexible URS (fURS) was tried over guidewire. If this attempt was unsuccessful, the procedure was stopped and a JJ stent was placed and the patient was scheduled for reoperation after three or four weeks.
After the UAS was placed, renal stones were fragmented by a holmium:YAG laser. Laser energy and pulse frequency were varied based on stone burden and density. If possible, lower pole stones were repositioned into the upper or middle calyx. Stone fragments over 2-3 mm were extracted by a nitinol basket catheter. A JJ stent was usually left in place according to surgeon preference.
During follow-up, the urinary ultrasound and KUB radiography were done in the follow-up visit after the first month. NCCT was performed in suspicious and necessary cases. Stone-free status was defined as no residual fragments or the presence of residual fragments up to 3 mm. Surgical success was defined as patients’ achievement of stone-free status after a single lithotripsy session without the need for additional sessions or ancillary procedures.