Renal tumour nephrometry score does not correlate with the risk of radiofrequency ablation complications

Objectives To assess whether the R . E . N . A . L . nephrometry score (consists of [ R ]adius [tumour size as maximal diameter], [ E ]xophytic/endophytic properties of the tumour, [ N ]earness of tumour deepest portion to the collecting system or sinus, [ A ]nterior [a]/posterior [p] descriptor and the [ L ]ocation relative to the polar line) is associated with complication risk in patients that have radiofrequency ablation ( RFA ) for small renal masses ( SRMs ). To evaluate a standardised system for predicting complication risks which has not been studied.Patients and Methods We reviewed the records of all patients who underwent RFA at our institution between M ay 2001 and M ay 2011. RFA was performed using a temperature‐based system and a 25‐ G nine‐tine array needle probe. Patients with preoperative imaging available for R . E . N . A . L . nephrometry scoring were included. R . E . N . A . L . composite scores, tertile stratification and preoperative patient characteristics were analysed for significance in relation to complications. Complications were defined using the C lavien‐ D indo classification system.Results In all, 199 patients had preoperative R . E . N . A . L . nephrometry scores available; 170 underwent percutaneous RFA and 29 laparoscopic RFA . The mean (range) A merican S ociety of A nesthesiologists ( ASA ) score was 2.6 (1–4). The mean (range) tumour size was 2.4 (0.7–5.4) cm. Overall, 14 complications were identified; 10 minor ( C lavien I – II ) and four major ( C lavien III – IV ). There was no significant association between complications and R . E . N . A . L . nephrometry score, R . E . N . A . L . nephrometry tertiles, tumour diameter, tumour location or ASA score ( P > 0.05).ConclusionR . E . N . A . L . nephrometry scoring fails to predict complications of RFA for SRMs when using a temperature‐based nine‐tine array probe.