Factors associated with digital flexible ureteroscopy management in kidney stone treatment: a prospective study

Background Digital flexible ureteroscopy (FURS) has become a standard minimally invasive approach for treating renal calculi, yet evidence from Vietnam remains limited. This study evaluated treatment outcomes and identified predictors of stone-free rate (SFR) following digital FURS. Methods A prospective observational study was conducted on 123 adults undergoing digital FURS for renal stones at Bach Mai Hospital (May 2023–July 2025). Preoperative CT was used to assess stone burden and lower pole anatomy. SFR was defined functionally as the absence of residual fragments >4 mm on ultrasound assessment. Univariate and multivariate logistic regression analyses were performed. Results Perioperative and 1-month postoperative SFR were both 75.6%. Multivariate analysis identified two independent associations with stone-free rate, including stone area ≤110 mm² (immediate OR = 5.61; 95% CI: 1.85–17.00; one-month OR = 6.20; 95% CI: 1.30–29.67) and absence of lower pole stones (perioperative OR = 3.65; one-month postoperative OR = 13.16). Conclusion Digital FURS demonstrates high efficacy and safety in renal stone management, with stone burden and lower pole anatomy emerging as the most important determinants of treatment outcomes.