Temporal study of renal volume losses in patients with robotic partial nephrectomies

Abstract

Purpose: Robotic partial nephrectomies by their nature are associated with renal volume loss. Our goal from this study is to examine renal volume loss over time post partial nephrectomy. Materials and Methods: Fifty patients were followed for 1-year post robotic partial nephrectomy with two-layer renorrhaphy and the sliding clip technique. This was done with a preoperative computed tomography (CT) scan to assess renal mass and location. Post robotic partial nephrectomy patients were imaged at time points 3-days, 6-months, and 12-months. Results: Patient demographics were 82% male with a median (IQR) age of 57 (45-67)and all were of Japanese descent. The medians (IQR) for warm ischemia time: 18 minutes (14-22), total operative time: 181.5 minutes (169.3-218.5), and estimated blood loss: 20 mL (10-50). The tumor characteristics had a median (IQR) diameter of 2.8 cm (2.5-3.4)with a RENAL score of 7 (6-8). The renal CT volumes showed median (IQR) volume losses at 3-days: -1% (-7.1, 1.8), 6-months: -15.3% (-20.6, -11.2), and 12-months: -16.3% (-19.0, -12.8). Significance was seen at the 3-days to 6-months comparison for volume loss (p<0.0001). Mean (SD) eGFR losses were as follows: at discharge 0.5% (12.9), 1-month -6.4% (11.8), 6-months -4.6% (9.8), and 12-months -3.6% (11.9). Statistical analysis showed significance for GFR loss at the comparison between discharge to 1-month and 6-months (p=0.01, p=0.04).Conclusion: The initial volume loss seen post-surgery from resected healthy tissue was not significant and only became relevant atlonger time points suggesting that loss could be from atrophy. Volume loss over time supports the hypothesis that suture renorrhaphy is a primary cause of volume loss when warm ischemia time is <25minutes.