Is 10/12 Fr Ureteral Access Sheath more Suitable for Flexible Ureteroscopic Lithotripsy?

Purpose: To choose the ideal UAS size for an unstented ureter in flexible ureteroscopic lithotripsy. Materials and Methods: A retrospective case-control study was conducted with patients treated with flexible ureteroscopic lithotripsy for renal calculi from 2005 to 2020. The patients were divided into two groups: smaller (10/12 Fr) vs. larger (12/14 Fr) calibre UAS. The outcome was the insertion success rate, systemic inflammatory response syndrome (SIRS) complication rate after the operation, ureteral wall injury, operative time, and stone-free rate. Results: Of the 1573 patients enrolled, 10/12 Fr UAS was used in 957 (Group A); 12/14 Fr UAS was used in the remaining patients (Group B). The insertion success rate was significantly better in Group A (91.2% vs. 86.9%, P = .006), with no significant difference between the groups regarding the stone-free rate, postoperative pain, operative time and hospital stay. The severity of ureteral visible lesions with 10/12 Fr UAS was significantly lower than that with larger UASs (80.1% vs 85.2%, P = .000). Despite no significant difference in the incidence of SIRS between the two groups, the incidence of SIRS in the 10/12 Fr group showed a sharp increase with stones >2 cm (17.0% vs. 8.5%, P = 0.037). Conclusion: The use of 10/12 Fr UAS had an advantage for the insertion success rate, avoiding ureteral wall injury and not increasing postoperative infectious complications in flexible ureteroscopic lithotripsy. We recommend the use of smaller calibre (10/12 Fr) UAS in patients with renal calculi < 2 cm.