399 Background: Recently, the R.E.N.A.L. nephrometry scoring system was introduced to objectively describe renal masses with respect to size, the degree to which they are exo/endophytic, the nearness to the collecting system, whether they are anterior or posterior and the location relative to polar lines. It is our aim to evaluate the R.E.N.A.L. nephrometry scoring system’s ability to predict functional renal loss attributed to nephron-sparing surgery (NSS). Methods: We evaluated 42 patients presenting with either an anatomic (32) or functionally solitary (10) kidneys undergoing partial nephrectomy (PN). Each renal unit was assigned a R.E.N.A.L. nephrometry score utilizing pre-operative cross-sectional imaging. The CKD−EPI equation was applied to serum creatinine levels to generate corresponding estimated glomerular filtration rates (eGFR). The difference between the eGFR at baseline and at post-operative time points served as a measurement of renal function loss attributed to PN. Results: Forty-two patients underwent PN with mean pre-operative eGFR of 61.5 mL/min/1.73m2. The median total nephrometry score was 8, ranging from 4–10. Twenty-eight (66.7%) of the renal lesions were ≤ 4 cm, 13 (31%) were between 4 and 7 cm, and 1 (2.4%) was >7 cm in diameter. The majority (54.8%) of the patients had tumors with more than 50% of tumor burden lying outside the expected renal border whereas 3 patients (7.1%) had tumors considered to be completely endophytic. Twenty-seven (64.3%) were within 4 mm of the collecting system. Tumor locations defined as: completely polar, interpolar, and completely central were assigned to 11, 15, and 16 lesions respectively. By post-operative month 6, the overall average eGFR of 53.9 mL/min/1.73m2 was significantly less (p = 0.0293) than the pre-operative value. However, we were unable to correlate change in post-operative eGFR with pre-operative total or individual R.E.N.A.L. scoring parameters. Conclusions: Neither the individual components of the R.E.N.A.L. nephrometry scoring system nor the total nephrometry score correlated with realized functional loss as assessed by eGFR in patients with a solitary kidney undergoing NSS.
1655: Predictive Value of 3 Dimensional Volume Rendered CT for Collecting System Entry and Tumor Size Prior to Nephron Sparing Surgery
