Comparison of Two Versus Four Weeks of Ureteral Stenting Prior to Ureteroscopy After Failed Primary Ureteral Access

This study proposes a non-randomized controlled trial comparing 2 weeks versus 4 weeks of DJ ureteral stenting in patients whose primary ureteral access failed during an initial attempt at FURS. The purpose is to determine whether a longer stenting period improves subsequent ureteral access. Participants: Adults aged 18-65 years with renal/upper ureteric stones ≤20 mm and failed primary access. Sample size: 198 patients - 99 in each group. Group A: Repeat FURS after 2 weeks of DJ stenting. Group B: Repeat FURS after 4 weeks of DJ stenting. Primary outcome: Successful placement of a 10/12-Fr ureteral access sheath during repeat FURS without additional dilation. Secondary outcomes: Stone-free rate and USSQ score. Stone-free definition: No residual stone fragment ≥4 mm on NCCT at 4 weeks after FURS. Analysis: t-test/Mann-Whitney U for numerical variables and Chi-square/Fisher's exact test for categorical variables, with p \< 0.05 considered significant.