Second-side efficiency advantage in robotic-assisted video-endoscopic inguinal lymphadenectomy for penile cancer.

INTRODUCTION: Robotic-assisted video-endoscopic inguinal lymphadenectomy (RAVEIL) reduces wound morbidity in penile cancer while maintaining oncological adequacy. During synchronous bilateral RAVEIL, we consistently observed that contralateral groin dissection was completed more rapidly than the first side with similar nodal yield. We term this phenomenon the 'second-side advantage' and report the first systematic quantification of this efficiency gain. PATIENTS AND METHODS: A retrospective analysis of 38-consecutive RAVEIL (21 patients) performed between 2019 and 2026 by a single surgeon was conducted. Seventeen patients underwent synchronous bilateral RAVEIL. Operative time and nodal yield were compared between first and second groins using paired t -tests. Cases were analysed according to actual operative sequence. Subgroup analysis by operative sequence and chronological learning curve analysis were performed to address potential confounders. RESULTS: Corrected for actual operative sequence, the mean operative time decreased from 88.8 ± 25.7 min on the first side to 73.2 ± 25.7 min on the second (mean reduction: 15.6 min, 95% confidence interval: 8.3-22.9 min; P = 0.0004). Lymph node yield was comparable (13.1 ± 7.0 vs. 12.6 ± 5.2 nodes; P = 0.59). The advantage was significant in both the right-to-left ( P = 0.0025) and left-to-right ( P = 0.034) subgroups, excluding a laterality effect. The size of the advantage did not correlate with chronological case rank ( r = 0.43, P = 0.088), excluding a learning curve artefact. CONCLUSIONS: Synchronous bilateral RAVEIL demonstrates a consistent, highly significant and large-effect intraoperative efficiency gain on the second side, independent of laterality and operative experience.