Two versus four weeks ureteral stenting prior to flexible ureteroscopy after failed primary ureteral access sheath insertion: a randomized trial

BACKGROUND: During Flexible ureteroscopy; Failed primary placement of the ureteral access sheath (UAS) or backloading of flexible ureteroscopy occurred in up to 22% of patients who required ureteric stent insertion for some time. This study was conducted to compare the outcomes of two versus four weeks of preoperative ureteral stenting in patients with failed primary ureteral access undergoing flexible ureteroscopy (FURS). PATIENTS AND METHODS: This single-blind, randomized controlled trial included 60 patients with upper and/or renal stones < 20 mm who had failed primary access during FURS between April 2024 and October 2025. Patients were randomized into 2 groups to insert a ureteral double-J stent for either 2 weeks (n = 30) or 4 weeks (n = 30) before the definite FURS. The primary endpoint was successful insertion of a 10/12 Fr ureteral access sheath (UAS). Secondary outcomes included stone-free rate (SFR) (assessed by a postoperative 4-week CTUT), operative time, complications, and stent-related symptoms (assessed by the Ureteral Stent Symptom Questionnaire (USSQ)). RESULTS: Baseline demographic and clinical characteristics were comparable between groups. Successful UAS insertion was achieved in 90% of the 2-week group and 93.3% of the 4-week group with no difference between groups (p = 0.64). No significant differences were found between groups regarding postoperative 4-week NCCT SFR (80.0% vs. 73.3%, p = 0.54), operative time (55 vs. 48.5 min, p = 0.44), or complication rates. Ureteric injuries were minor (6.7% in each group). Stent-related symptoms measured by USSQ did not significantly differ (p = 0.24). CONCLUSION: In this randomized trial, no statistically significant differences were observed between 2-week and 4-week preoperative stenting regarding UAS insertion success, stone-free rate, operative time, or complication rates. These findings suggest that prolonging stent dwell time beyond 2 weeks may not provide a substantial additional benefit in this patient population. TRIAL REGISTRATION: The trial was retrospectively registered in 12/2024 on clinicaltrials.gov under the number: NCT06761378.