Prospective assessment of the adherent perinephric fat in partial nephrectomies: Predictors and impact on peri-operative outcomes.

Abstract

543 Background: The surgical complexity of partial nephrectomy (PN) can be partly anticipated using renal morphometric scores that do not consider patient related issues such as obesity or perirenal fat. Our primary objective was to prospectively assess the predictive factors for adherent perinephric fat (APF) and its impact on the onset of complications. The secondary objective was to correlate the surgical appraising with the histological reality of APF. Methods: Fifty consecutive patients undergoing robotic or open PN were prospectively included from November 2014 to March 2015. The previously published Mayo adhesive probability score (MAP score) was calculated and compared to the per-operative surgical assessment of APF using a 0 to 3 scale (APF being defined by a score ≥ 2). Fat was analyzed histologically for fibrosis (HES staining and picrosirius red) and inflammatory infiltrate of macrophages (immunohistochemistry using anti-CD68 antibody). Results: APF was present in 18 patients (36%), with no impact on surgical approach (31.3% vs 38.9 robotic way, without surgical conversion). APF was associated with longer operating time (169 min vs. 146 min, p = 0.036) and increased blood loss (469 mL vs 179 mL, p = 0.014). Duration of clamping, rate of positive margins, blood transfusion and the Clavien-Dindo score were not different (Table 1). In multivariate analysis, only male gender (p = 0.044), age (p = 0.014) and MAP score (p = 0.00057) were significant predictors of APF. Histologically, APF was characterized by a marked fibrosis but no macrophage infiltrate. Conclusions: APF can be accurately predicted using radio-clinical data as the MAP score, combined with age and gender. APF is associated with increased operative time and blood loss without impacting the rate of complications. Histological analysis of APF demonstrates significant fibrosis without inflammatory infiltrate. [Table: see text]