Factors affecting use of flexible ureteroscope in large renal stones; stone size or stone composition

Introduction: After advances in flexible ureteroscopes' design, accessories, and lithotripters, flexible ureteroscope has been used widely for the treatment of large renal calculi >2 cm. Objectives: The objective was to evaluate the role of flexible ureteroscopy with laser lithotripsy in the treatment of large renal calculi >2 cm and find out which factor can affect the results. Patients and Methods: Prospectively, we have studied 47 patients who have passed through flexible ureteroscopy with laser lithotripsy for renal calculi >2 cm. Preoperative, operative, and postoperative data were recorded. Results and complications were recorded, too. Results: In 47 patients, the mean stone size is 26.2 ± 4.1 cm and the total stone-free rate (SFR) is 89.4%, while in stone size ≤3 cm, the SFR is 90.7%, and for stone size >3 cm, the SFR is 75%. Overall stone density is 1020 ± 286 HU. The SFR is 95.5% in stones ≤1000 HU and 84% in stones >1000 HU. The mean operative time is 99.2 ± 29.3 min. The intraoperative complications are 17%, while postoperative complications are 36% and all complications are mild. Conclusion: Flexible ureterorenoscopy (FURS) is safe and effective for the treatment of large renal calculi >2 cm. Stones >3 cm may have lower results even after staged therapy.