Flexible ureteroscopic management of calyceal diverticular stones: outcomes and validation of the novel L.E.N.S.O. radiological complexity score

Objective To evaluate the clinical outcomes of flexible ureteroscopic management of calyceal diverticular stones and to validate the novel L.E.N.S.O. Radiological Complexity Score as a predictor of procedural difficulty and stone-free outcomes. Methods This retrospective observational study included 52 consecutive symptomatic patients with calyceal diverticular stones who underwent retrograde intrarenal surgery (RIRS) with laser infundibulotomy between January 2020 and January 2026. Preoperative radiological parameters including diverticulum location (L), excretion (E), neck visibility (N), stone size (S), and orientation (O) were scored to calculate the L.E.N.S.O. score (range 5–10). Patients were categorized as low (score ≤ 6), moderate (score 7–8), or high complexity (score ≥ 9). Primary outcomes included stone-free rate (SFR) and technical success. Secondary outcomes included operative time, complications, hospital stay, and need for auxiliary procedures. Results The overall stone-free rate at 3 months was 69.2%. The L.E.N.S.O. score demonstrated significant correlation with SFR at 1 month ( p < 0.001) and 3 months ( p < 0.001), operative time ( p = 0.002), and need for auxiliary procedures ( p < 0.001). Low-complexity patients ( n = 19, 36.5%) had SFR of 94.7% at 3 months with no auxiliary procedures, while high-complexity patients ( n = 8, 15.4%) had SFR of 25.0% and 75.0% required auxiliary procedures. Multivariate analysis identified poor excretion (OR 0.24, p = 0.01) and non-visible neck on imaging (OR 0.26, p = 0.02) as independent predictors of treatment failure. Conclusion Flexible ureteroscopic management is effective for calyceal diverticular stones, particularly in selected patients with favorable anatomy. The L.E.N.S.O. Radiological Complexity Score is a simple, reproducible tool that reliably predicts procedural difficulty and stone-free outcomes, enabling personalized surgical planning and patient counselling.