Is diameter‐axial‐polar scoring predictive of renal functional damage in patients undergoing partial nephrectomy? An evaluation using technetium Tc 99m (99Tcm) diethylene‐triamine‐penta‐acetic acid (DTPA) glomerular filtration rate

Objective To identify the effects of diameter-axial-polar (DAP) scoring and other clinical variables on renal functional outcomes after partial nephrectomy (PN). Material and Methods A total of 59 patients with complete radiographic, clinical and follow-up information were included for analysis. Technetium Tc 99m (99Tcm)-diethylene-triamine-penta-acetic acid (DTPA) renal scintigraphy was used to determine the glomerular filtration rate (GFR) of both kidneys and each kidney individually. All cross-sectional images were reviewed by a single radiologist and a DAP score was assigned. Results The median decline in total GFR after PN was 13% at a median follow-up of 12 months (from 86.8 to 76.2 mL/min per 1.73 m2, P < 0.001). The median GFR of the operated kidney showed a significant decrease peri-operatively (42.4 to 27.1 mL/min per 1.73 m2, P < 0.001). The function of the contralateral kidney showed a significant increase (43.5 to 48.8 mL/min per 1.73 m2, P < 0.001). On multivariate analysis, preoperative total GFR, ischaemia time and DAP sum score were independent predictors of absolute functional decline of the affected kidney (all P < 0.001), while only preoperative total GFR and DAP sum score were significantly associated with the total absolute GFR reduction (all P < 0.001). Conclusion Preoperative renal function status and DAP score of renal tumours are the primary determinants of long-term functional outcomes after PN, but renal ischaemia damage to the operated kidney after PN is possibly masked by functional compensation of the contralateral healthy kidney if only overall renal function is assessed.