Comparison of diameter-axial-polar nephrometry score and RENAL nephrometry score for surgical outcomes following laparoscopic partial nephrectomy

Objectives: To compare diameter-axial-polar nephrometry score with RENAL nephrometry score for surgical outcomes after laparoscopic partial nephrectomy.

Methods: We retrospectively reviewed data from 134 patients who underwent laparoscopic partial nephrectomy, using diameter-axial-polar and RENAL scores. We analyzed data for warm ischemic time and estimated blood loss intraoperatively, and percentage change in estimated glomerular filtration rate 6 months and 1 year postoperatively. Both scores were classified as low-, middle- and high-risk, and were used to compare the three analyzed parameters.

Results: The median tumor size was 2.3 cm (range 1.0-5.4 cm); warm ischemic time was 25.4 min (range 6.5-57 min); and at 6 months and 1 year, percentage change in estimated glomerular filtration rate was 93% (range 51.7-133.3%) and 91% (range 49.4-137.6%), respectively. There were no significant differences in warm ischemic time and estimated blood loss for RENAL between risk groups (P = 0.38 and 0.09, respectively), but significant differences between groups for diameter-axial-polar score (P = 0.02 and 0.01, respectively). There were no significant differences in either score between groups for percentage change in estimated glomerular filtration rate at 6 months and 1 year. A total of 27 high-risk cases with a diameter-axial-polar score of seven points underwent laparoscopic partial nephrectomy safely; all three cases with a diameter-axial-polar score of eight points were converted to open partial nephrectomy.

Conclusions: Diameter-axial-polar score seems to estimate the complexity of tumor characteristics in patients undergoing laparoscopic partial nephrectomy better than RENAL score. It has a better correlation with warm ischemic time and estimated blood loss.