Modified R.E.N.A.L nephrometry score for predicting the outcome following partial nephrectomy

Abstract Background It was difficult to compare the outcome of partial nephrectomy among different studies due to the absence of standardized description of different renal masses. This problem led to the development of nephrometry scoring systems. R.E.N.A.L. is among the commonest nephrometry scoring systems; however, some studies failed to find any relation between R.E.N.A.L. with perioperative outcome. We evaluated our designed newly modified nephrometry score in prediction of outcome following partial nephrectomy and compared its predictability versus original R.E.N.A.L. Methods Fifty-one patients with cT1-2N0M0 renal masses amenable for partial nephrectomy were included prospectively. Different perioperative outcome variables were compared according to complexity level in R.E.N.A.L. and the newly modified nephrometry score. Results Clinical staging was T1a (21.6%), T1b (49%), T2a (25.5%), T2b (3.9%). Median R.E.N.A.L. was 9 (4–12). Hilar position and intrarenal pelvis were detected in 19.6% and 68.6%. Low, moderate and high complexity masses were found in 21.6%, 39.2% and 39.2%. Complications and rate of conversion to radical nephrectomy were 17 (33.3%) and 4 (7.8%). The only significantly affected variable (p = 0.039) by R.E.N.A.L. was rate of secondary intervention, but it was higher in low than in high complexity level. In the newly modified nephrometry score, complications (p = 0.037) and rate of positive surgical margin (p = 0.049) were significantly higher with increased complexity level. Although other variables (pelvi-calyceal system entry, operative time, blood loss, hemoglobin loss, blood transfusion and conversion to radical nephrectomy) did not show statistically significant difference according to both scores, they were better associated with the complexity level in the newly modified nephrometry score with their remarkable increase in the high when compared to the low complexity level. Conclusions The newly modified nephrometry score was associated with better prediction of outcome of partial nephrectomy when compared to R.E.N.A.L.