Safety and complications of upper pole puncture in supine percutaneous nephrolithotomy

OBJECTIVE: Supine percutaneous nephrolithotomy (PCNL) has gained attention as a viable alternative to the traditional/historical prone approach for the treatment of large renal stones. However, concerns remain regarding the safety and feasibility of upper calyx punctures in the supine position, particularly for upper-pole access. This multicenter, retrospective cohort study evaluated the safety and stone-free rates of upper-pole punctures in supine PCNL, comparing outcomes with middle and lower calyx punctures and with literature on prone PCNL. METHODS: This retrospective study analyzed supine PCNL cases performed between 2009 and 2019 across eight international centers, categorizing patients by calyx of entry (upper, middle, or lower). Patients who required multiple calyx entries were excluded. Demographics, surgical details, and outcomes were recorded, including complications and stone-free rates. We used logistic regression to assess the association between stone-free rates and calyx puncture sites, adjusting for age, gender, Guy's Stone Score, and ASA score. Based on the initial findings, we performed a second multivariable logistic regression among patients undergoing upper calyx puncture using the same covariates. ANOVA was used to compare the means of quantitative variables, and Chi-square tests assessed associations between categorical variables. Bonferroni adjustment was applied when appropriate. RESULTS: Among 989 patients, 10% had upper, 28.5% middle, and 61.5% lower calyx punctures. No significant differences were found in overall complication rates when comparing upper, middle, and lower calyces. Thoracic complications were rare and did not differ significantly across calyces (p = 0.74). Upper calyx punctures had lower stone-free rates (51%) compared to middle (77.7%) and lower (62.8%) punctures (p < 0.001). The overall complication rate did not differ significantly (p = 0.82). According to the logistic regression, patients with a middle puncture site had 2.98 times higher odds of a stone-free outcome than those with an upper puncture site (OR, 2.98; 95% CI, 1.69-5.29). In contrast, patients with a lower puncture site did not have a significant difference in stone-free rates compared to those with an upper puncture (OR = 1.10, 95% CI: 0.64, 1.86, p = 0.7). Among patients undergoing upper calyx puncture, Guy's Stone Score 4 was independently associated with lower odds of achieving stone-free status (OR 0.20, 95% CI 0.04-0.91; p = 0.045). No significant associations were observed for age, gender, or ASA classification. CONCLUSION: Upper calyx punctures showed similar complication rates to middle and lower calyx punctures, with slightly lower stone-free rates likely due to higher stone complexity. These findings support the feasibility, safety, and efficacy of supine PCNL for upper calyx access.