Volume 14, Supplement 1
Original Article / Published: April 2026
DOI: https://www.doi.org/10.57045/jemis/1410426.pp22-23
K. Petkova, K. Hristov, O. Gatsev, V. Todorova, I. Saltirov
Department of Urology and Nephrology, Military Medical Academy, Sofia, Bulgaria
Abstract
Introduction and Objective: Recently, retrograde intrarenal surgery (RIRS) with flexible and navigable ureteral access sheath (FANS) is expanding the limits of retrograde stone treatment. The introduction of small calibre flexible ureteroscopes has been shown to provide effective management of renal and ureteral stones with the potential of reduced complication rate from instrument miniaturization. The objective of this study is to compare the efficacy and safety of RIRS with FANS performed with 6.3 and 7.5 Fr flexible ureteroscopes.
Matherials and methods: A total of 49 RIRS with FANS procedures performed between June 2025 and December 2025 were analyzed. 20 procedures were performed with 7.5 Fr flexible ureteroscope and 10/12 Fr FANS and 29 procedures – with 6.3 Fr flexible ureteroscope and 9.5/11 Fr FANS. Stone-free rates (SFR) and complication rates were compared between groups.
Results: Patients’ preoperative characteristics did not differ significantly between groups. Preoperative stent was placed in 25% of patients treated with 7.5 Fr endoscope and 31% of those treated with 6.3 Fr endoscope (p=0.754), with the main reason for preoperative stenting being emergency stenting in the majority of the cases and failed access in 1 patient, treated with 7.5 Fr endoscope. Mean renal stone size was 10±7.6 mm vs 8.2±7.2 mm (p=0.534) for 7.5 and 6.3 Fr endoscope groups, respectively. Mean ureteral stone size was 8.4±4.3 mm vs 7.8±5.5 mm (p=0.763), respectively. SFR, defined as no residual fragments larger than 2 mm, was 75% and 82.8% for 7.5 and 6.3 Fr endoscope groups, respectively (p=0.508). There were no intraoperative and postoperative complications in both groups. Flexible endoscope was able to access all parts of the kidney in all cases. FANS was able to access all parts of the kidney in 78.9% and 62.1%(p=0.181) for 7.5 and 6.3 Fr endoscope groups, respectively, with the main reason of failed access being tight ureter in 10% and 23.9%, respectively (p=0.338).
Conclusion: Both 7.5 Fr and 6.3 Fr flexible endoscopes combined with 10/12 Fr and 9.5/11 Fr FANS are effective and safe treatment options for renal and ureteral stones. The smaller calibre instrument and FANS may offer an advantage in tight ureters and ureteral strictures, enhancing kidney access and precluding the need to abort the procedure and consider second-look in cases with non-compliant ureter.
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How to cite this article:
K. Petkova, K. Hristov, O. Gatsev, V. Todorova, I. Saltirov. Comparative analysis of the efficacy and safety of 6.3 Fr ureteroscope versus 7.5Fr flexible ureteroscope for retrograde intrarenal surgery (RIRS) with flexible and navigable access sheath (FANS). Journal of Endourology and Minimally Invasive Surgery (Bulgaria), 2026; 14(1): 22-23
Corresponding author:
Assoc. prof. Kremena Petkova MD, PhD
Clinic of Urology
Military Medical Academy of Sofia
Department of Urology and Nephrology, Clinic of Urology
3 “Georgi Sofiiski” blvd., Sofia 1606
Email: dr.k.petkova@gmail.com
Phone: +359 88 762 6583