In which cases does collecting system entry occur in robot-assisted partial nephrectomy? Development of a novel predictive model based on the contact surface area of the tumor to the renal parenchyma

Abstract

Background Collecting system entry in robot-assisted partial nephrectomy may occur even in cases showing a low N factor in the R.E.N.A.L nephrometry score. Therefore, we focused on the tumor contact surface area with the adjacent renal parenchyma and attempted to construct a novel predictive model for collecting system entry. Methods Among 190 patients who underwent robot-assisted partial nephrectomy at our institution from 2015 to 2021, 94 patients with a low N factor (12) were analyzed. Contact surface was measured with three-dimensional imaging software and defined as the C factor, classified as C1, < 10 cm2; C2, ≥ 10 and < 15 cm2; and C3: ≥ 15 cm2. Additionally, a modified R factor (mR) was classified as mR1, < 20 mm; mR2, ≥ 20 and < 40 mm; and mR3, ≥ 40 mm. We discussed the factors influencing collecting system entry, including the C factor, and created a novel collecting system entry predictive model. Results Collecting system entry was observed in 32 patients with a low N factor (34%). The C factor was the only independent predictive factor for collecting system entry in multivariate regression analysis (odds ratio: 4.195, 95% CI: 2.160–8.146, p < 0.0001). Models including the C factor showed better discriminative power than the models without the C factor. Conclusions The new predictive model, including the C factor in N1-2 cases, may be beneficial, considering its indication for preoperative ureteral catheter placement in patients undergoing robot-assisted partial nephrectomy.

A new tridimensional effective method to calculate Real Contact Surface Area (RCSA) between renal tumor and surrounding kidney parenchyma: An Innovative Tool with predictive power of intraoperative outcomes in nephron sparing surgery

“…They found the CSA to be a predictor of the decrease rate of eGFR and to be associate with the decrease of operated parenchyma. Umemoto et al [21] proposed organ segmentation using the software Synapse, and after reconstruction, they simulated the removal of the tumor and measured the area of contact as the parenchymal area removed. However, their method lacks a proper estimation technique for accurate CSA values, and considering CSA as the area post-surgery is not a correct measure.…”