Patients were performed under general anesthesia in the oblique supine lithotomy position. Initially, preliminary ureteroscopy was performed with a semirigid 8/9.8 Fr ureteroscope guided by zebra guide wire. Next, the patented tip flexible pressure-controlling ureteral access sheath (UAS,12/14 Fr) was inserted along the guidewire without the fluoroscopic guidance. The fully automatic mode was chosen to operate the platform.The pressure sensory and suctioning channels of UAS were connected to the irrigation and suctioning platform. After water injection, zero calibration was performed at platform. Perfusion flow rate was then set at 100-150 ml/min, the renal pelvic pressure (RPP) control value was set at -15~5 mmHg, the RPP warning value was set at 20 mmHg, and the RPP maximum value was set at 30 mmHg. Intraoperatively, a holmium laser was used to crush the stone at 1.5-2.0 J/pulse with a frequency of 20-30 pulses/s ( (CHUNHUI, CHINA, 276µm).

Patients were performed under general anesthesia. The patient was first placed in a lithotomy position. A 5 Fr ureteral catheter was then inserted retrogradely into the renal pelvis through cystoscopy or ureteroscopy , and saline was continuously infused to produce artificial hydronephrosis. The patient was then placed in the prone position. Ultrasound-guided percutaneous punctures were made with an 18-gauge coaxial needle into the targeted calix. The puncture point was in the 12th rib infracostal margin, between the posterior axillary line and scapula line. A Zebra guidewire was inserted and fixed. The puncture needle was then removed. After a 0.5-0.7 cm skin incision was made, the percutaneous tract was dilated serially over the guidewire with a fascial dilator to 18Fr. Holmium laser lithotripsy at 1.5-2.0 J/pulse with a frequency of 20-30 pulses/s (CHUNHUI, CHINA, 550µm) was performed with a 18 Fr peel-away sheath.

RIRS with tip flexible pressure-controlling ureteral access sheath versus mini PCNL for the treatment of 2-3-cm kidney stones

No residual stone or stone fragments less than 2 mm on low-dose CT scan at postoperative day 1-7 are defined as stone free.

No residual stone or stone fragments less than 2 mm on kidney, ureter, and bladder at 1 months are defined as stone free.

The operation time of RIRS and mini PCNL was defined as the time from the insertion of the suction sheath and renal puncture to the end of the operation