Effective treatment of lower pole (LP) renal calculi has been a challenging issue for endourologists. However, the emergence of retrograde intrarenal surgery (RIRS) coupling with flexible suction ureteral access sheath (S-UAS) has changed the landscape of stone management as the treatment modality improves stone free rate at all sites. The aim of the study is to investigate the efficacy and safety of RIRS with S-UAS in treating single LP calculi based on a single center experience.

We conducted a retrospective cohort study on 55 patients who underwent unilateral RIRS using S-UAS due to single LPrenal calculi. Primary outcome was stone free rate (SFR), and the stone free status was assessed with kidney-ureter-bladder X-ray plain film immediately after operation. Moreover, secondary outcomes included perioperative outcomes (i.e. operative time, length of hospital stay) and perioperative complications classified according to the Dindo-modified Clavien System.

A total of 50 patients (comprising 28 females and 22 males) with a mean age of 58.16 years were included in this study. The mean stone size was 15.44 mm, and the mean duration of the surgical procedure was 30.16 minutes. The overall stone-free rate (SFR) was 83%. Within the subgroup of patients with smaller stones (< 10 mm), the SFR was 85.71%, while for those with larger stones (≥ 10 mm), the SFR was slightly lower at 82.86%. The mean length of hospital stay after operation was 1.03 days. Perioperative complication rate was 4% and consisted of only grade I cases.

Retrograde intrarenal surgery (RIRS) with innovative S-UAS demonstrated a great efficacy in treating LP renal calculi while maintaining a reasonable rate of complications. Our results suggest that this innovative approach could improve renal stone management by addressing the challenges posed by complex lower pelvicalyceal anatomy.