The modified R.E.N.A.L. nephrometry score comprising longitudinal tumor localization is better for predicting intraoperative collecting system entry during robot‐assisted partial nephrectomy

Abstract

AbstractIntroductionDuring robot‐assisted partial nephrectomy (RAPN) for small renal tumors, intraoperative collecting system entry (CSE) is a factor that defines the surgical complexity (prolonged inhibition time), complications (postoperative urinary leakage), and requirements for intraoperative ureteral catheter insertion.MethodsFrom October 2018 to March 2023, 113 consecutive patients who underwent RAPN for clinical T1‐stage renal tumors were included in this single‐center retrospective validation study. Patient and tumor characteristics associated with intraoperative CSE were analyzed to validate the modified R.E.N.A.L. nephrometry score (RNS).ResultsIntraoperative CSE was observed in 54 patients (48%). During the univariate analysis, upper pole tumor location, tumor size, renal sinus invasion, and urinary tract proximity were significant predictors of intraoperative CSE. Subsequent multivariate analysis identified upper pole tumor location (upper vs. lower: odds ratio [OR], 5.36; p = .014) and nearness of the tumor to the collecting system or sinus (>4 but <7 mm vs. ≥7 mm: OR, 4.17; p = .04; ≤4 mm vs. ≥7 mm: OR, 32.71; p < .001) as independent predictors of intraoperative CSE.ConclusionThe modified RNS, which includes longitudinal tumor localization as a variable instead of polar line‐based tumor location, may be a better risk classification tool than the conventional RNS (area under the receiver‐operating characteristic curve: 0.816 vs. 0.754) for determining the need for intraoperative ureteral catheter insertion and predicting intraoperative CSE and surgical complexity.