Purpose: To evaluate the effectiveness and safety of combining 7.5Fr flexible ureteroscope with 10Fr ureteral access sheath performed in patients with renal calculi under 2cm. Materials and methods: We prospectively involved 10 patients with renal calculi < 2cm who underwent holmium laser lithotripsy using the combination of 7.5Fr flexible ureteroscope and a 10Fr ureteral access sheath without double-J stents pre-reserved. The patients' profiles, including preoperative, operative information,

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... d postoperative complications, were recorded. Results: The success rate of sheath placement was 100% with the operation time of 55.0 ± 20.0 min, while the lithotripsy time of 150.4 ± 199.0 s. Due to the grade-1 injury of ureter, the double-J stent was retained in two cases for a month. Moreover, the duration of stent-keeping was 18.3 ± 20.13 hours, the hospitalization duration after operation was 45.6 ± 15.5 h, and the pain score after 24 hours postoperatively was 4.3 ± 3.5, respectively. Hemoglobin decreased by 5.0 ± 9.2 g/L and creatinine increased by 1.9 ± 6.6 μmol/L postoperatively, and none of the patients suffered from fever or hemorrhage. The SFR was 90.0% in a month after surgery. In terms of the symptom score of stents, overactive bladder symptom score was 1.7 ± 1.5, international prostate symptom score of 3.3 ± 2.8, and quality of life of 1.3 ± 1.7. Conclusion: Combining 7.5Fr flexible ureteroscope with 10Fr ureteral access sheath is recommended as a safe option for treating renal calculi < 2cm with high rate of sheath placement and lower rate of complication.