Membrane anatomy-guided robot-assisted partial nephrectomy: operational definition and association with warm ischemia time in a single-surgeon cohort.

BACKGROUND

A standardized anatomical framework for robot-assisted partial nephrectomy (RAPN) is lacking. This study evaluates a stepwise membrane anatomy-guided pathway and its association with warm ischemia time (WIT) and clamping-phase efficiency, controlling for surgical experience and temporal confounding.

METHODS

We evaluated 151 consecutive RAPN cases (30 conventional vs. 121 membrane anatomy-guided) performed by a single-center, single-surgeon cohort using the da Vinci Xi System (2022-2025). Multivariable linear regression with HC3 robust standard errors was performed to assess the primary outcome (WIT), adjusting for clinical covariates and nonlinear cumulative case sequence (natural cubic spline, df = 3). Chronology-adjusted sensitivity analyses and propensity-score overlap weighting were conducted.

RESULTS

Despite substantial chronological overlap between pathways, the membrane-guided pathway was independently associated with a 4.05-min reduction in mean WIT (95% CI -6.82 to -1.28; P = 0.004) without compromising surgical margin safety. This effect was consistent across linear, calendar-time, propensity-weighted, and overlap-cohort sensitivity analyses (-3.67 to -4.19 min; all P < 0.05). The membrane-guided approach also significantly increased the odds of WIT ≤ 25 min (adjusted OR 5.25; P = 0.003) and modified Trifecta achievement (adjusted OR 4.97; P = 0.005).

CONCLUSION

The membrane anatomy-guided pathway consistently improves clamping-phase efficiency and shortens WIT in RAPN after accounting for learning curves and temporal trends. Given the retrospective design, these findings reflect associative rather than definitive causal effects.