Efficacy of Lower Calyceal Access in Percutaneous Nephrolithotomy for Staghorn Renal Calculi: A Single-Centre Experience

Abstract Background Staghorn calculi represent a complex form of nephrolithiasis associated with recurrent infection, renal deterioration, and significant morbidity. Percutaneous nephrolithotomy (PCNL) remains the gold-standard treatment; however, the optimal calyceal access approach for achieving effective stone clearance with minimal morbidity has not been definitively established. We aimed to evaluate the efficacy and safety of lower calyceal access in PCNL for staghorn calculi and to compare perioperative outcomes between lower and non-lower calyceal access approaches. Methods We conducted a retrospective cohort study of PCNL performed for staghorn calculi between 2016 and 2024 at a single tertiary centre. The renal unit (stone episode) was the unit of analysis; 111 renal units in 104 patients met the inclusion criteria, having postoperative imaging obtained within 90 days of the relevant PCNL procedure. The primary outcome was the final stone-free rate (SFR) per renal unit, defined as no visible residual fragment or a residual fragment < 4 mm on any postoperative imaging modality after the last PCNL session; the single-session SFR after the index procedure was a secondary outcome. Second-look PCNL was counted as part of the PCNL treatment course. Perioperative outcomes (complication rate [Clavien–Dindo], haemoglobin change, length of stay, operative time, and the number of puncture attempts) were analysed at the level of the PCNL procedure, and the need for second-look PCNL at the level of the renal unit. Categorical variables were compared using Pearson’s chi-squared or Fisher’s exact test and continuous variables using the Wilcoxon rank-sum test; multivariable logistic regression adjusted for age, sex, and stone burden. Results Lower calyceal access was used in 83.8% of renal units. The final PCNL stone-free rate, assessed after the final PCNL session and including second-look PCNL, was 74.8% per renal unit (single-session 44.1%), with no significant difference between lower and non-lower access (72.0% vs 88.9%, p = 0.233). The procedure-level complication rate (11.7% vs 6.9%, p = 0.741), haemoglobin change, length of stay, and number of puncture attempts were comparable between groups. On multivariable analysis, lower calyceal access was not independently associated with the final stone-free rate (adjusted odds ratio 0.43, 95% CI 0.09–2.09, p = 0.293); no covariate was significantly associated with stone clearance. Conclusions Lower calyceal access is the dominant approach for staghorn PCNL and achieves stone-free, complication, and perioperative outcomes comparable to non-lower access approaches. These findings support lower calyceal access as a safe and effective default strategy when anatomically possible, with non-lower or additional access reserved for stones that cannot be adequately cleared through a lower-pole approach.