Comparison of flexible ureteroscopic suction techniques: efficacy and safety of flexible and navigable access sheath (FANS) vs. direct in-scope suction (DISS) in the management of 2-3 cm lower pole renal stones

Abstract

This study compares the efficacy and safety of two techniques for flexible ureteroscopy (FURS) in managing 2-3 cm lower pole renal stones: the use of flexible and navigable access sheath (FANS) versus direct in-scope suction (DISS) without an access sheath. A retrospective analysis of 60 patients undergoing FURS for lower pole renal stones was conducted between March 2023 and January 2025. Group 1 (n = 32) underwent FANS-assisted procedures, while Group 2 (n = 28) underwent sheathless FURS with DISS. Stone-free rates (SFR) were assessed with non-contrast computed tomography (NCCT) after four weeks. Operative time, peri- and postoperative complications, and hospitalization duration were also compared. The mean operative time was significantly shorter in the FANS group (71.8 ± 11.5 min) compared to the DISS group (79.1 ± 11.7 min, p = 0.026). The difference between the SFRs obtained in the FANS group (62.5%) and the DISS group (46.4%) after the first session was not statistically significant (p = 0.162). After the second session, SFRs were also comparable (87.5% vs. 82.1%, p = 0.412) (Residual stones < 4 mm were considered stone-free). Completely stone-free rates (CSFR), defined as the absence of residual fragments after the first session were 43.7% in the FANS group and 32.1% in the DISS group (p = 0.256), while after the second session, these rates increased to 84.3% and 75%, respectively (p = 0.280). Postoperative fever rates (9.3% vs. 10.7%, p = 0.598) and hospitalization duration (2.5 ± 1.3 vs. 2.6 ± 1.4 days, p = 0.819) were similar. Both techniques achieved high overall SFRs for large lower pole stones in a staged manner. However, FANS was associated with a shorter operative time. While DISS eliminates the need for an access sheath, its longer operative time may be a limitation. Larger studies are needed to further evaluate these techniques.

Keywords: Access sheath; Direct in scope; Flexible; Lower pole; Navigable; Suction.

Fig. 1

Flexible and navigable access sheath that pushed into the lower renal calyceal position under the guidance of the flexible ureterorenoscope

Fig. 2

Direct in-scope suction system that introduced over the placed guidewire and navigated into the renal pelvis without the use of an access sheath