Off-Clamp versus On-Clamp Robotic Partial Nephrectomy: A Multicenter Match-Paired Case-Control Study

Introduction: The aim of this study was to compare the outcomes of on-clamp and off-clamp robotic partial nephrectomy (RPN). Materials and Methods: The charts of all patients who underwent an RPN at 8 institutions between 2010 and 2014 were retrospectively reviewed. The patients who underwent an off-clamp RPN were matched to on-clamp RPN in a 1-4 fashion according to the following variables: RENAL score, tumor size and surgeon's experience. Pre-, intra-, and postoperative data were compared between both groups. Results: Among 525 RPN, 26 were performed off-clamp (5%). They were matched to 104 on-clamp RPN. The complications rate (15.5 vs. 7.7%, p = 0.53), major complications rate (4.9 vs. 3.9%; p = 0.82), and transfusions rate (0 vs. 4.9%; p = 0.58) did not differ significantly between the clamped and unclamped groups. Conversely, estimated blood loss was higher in the off-clamp group (266.4 vs. 284.6 mL, p = 0.048) and so was the rate of conversion to radical nephrectomy (0 vs. 7.7%, p = 0.04). Postoperative preservation of renal function was comparable in both groups. Conclusion: Off-clamp RPN is feasible for a small subgroup of renal tumors without increased risk of postoperative complications but at the cost of higher estimated blood loss and increased risk of conversion to radical nephrectomy.