Modified Nephrometry Score With Body Mass Index More Accurately Predicts Ischemic Time in Transabdominal Laparoscopic Partial Nephrectomy for Small Renal Masses

Abstract

ObjectiveTo accurately predict the ischemic time (IT) and select candidates for transabdominal laparoscopic partial nephrectomy (LPN). MethodsTransabdominal LPN was performed for 135 Japanese patients with renal masses <7 cm in diameter between 2009 and 2016 by a single surgeon in a single institute. The renal parenchymal sutures were done with a combination of felt, Hem-o-lok and Lapra-Ty. The original R.E.N.A.L. nephreometry score (NS) was modified as follows. In terms of the tumor size (R), 1, 2, and 3 points were given for ≤2.5, 2.5-4, and >4 cm, respectively. For tumor location (A), 1, 2, and 3 points were given for anterior, on the coronal plane, and posterior, respectively. ResultsThe median IT was 24.6 minutes. Using the original NS, 64, 65, and 6 patients were categorized into low (4-6), moderate (7-9), and high (10-12) complexity, respectively. With the modified NS, 42, 75, and 18 patients were categorized into low (5-7), moderate (8-11), and high (12-15) complexity, respectively. Pearson's correlation coefficient (R) between the original NS and IT was 0.297, whereas the R was improved to 0.388 when the modified NS was employed. If the modified NS was low complexity, 95.2% achieved IT <30 minutes. Of them, none showed IT ≥30 minutes if the body mass index was <25 kg/m2. ConclusionThe modified NS had a better correlation to the IT than the original NS for patients with tumor sizes <7 cm who underwent transabdominal LPN. The modified NS with body mass index is a practical tool to select candidates for transabdominal LPN.