Introduction

Adherent perinephric fat (APF) is a risk factor for surgical difficulty during partial nephrectomy. No previous report has analyzed pure host-related risk factors of APF among individuals without cancer. Here, we assessed risk factors and characteristics of APF in healthy individuals.

Methods

Men who underwent laparoscopic donor nephrectomy between 2009 and 2014 were included in the present study. Based on retrospective review of video-recorded surgical procedures during anterior perinephric fat dissection, the severity of APF was categorized into the following three groups: non-APF (0), APF (1), and severe APF (2). The relationship between APF severity and clinical/radiographic features was evaluated. The relationship between cytokine expression in perinephric fat tissue (PAT)-conditioned medium and APF severity was also assessed using SearchLight Multiplex assays.

Results

Of the 92 patients, 43 (46.7%) and 8 (8.7%) were categorized as having APF and severe APF, respectively. Mean operative duration was significantly associated with APF severity (trend, P = 0.00248), and patients with severe APF had a significantly higher estimated blood loss than those without (P = 0.002). No difference in postoperative serum creatinine levels or rates of delayed graft function in recipients was observed among the three groups. Gender, body mass index, perinephric fat area, stranding, and thickness were significantly associated with severe APF. On multivariate analysis, perinephric fat area (OR, 1.189; P = 0.005) and the presence of renal stranding (OR, 14.450; P = 0.037) were identified as independent risk factors for severe APF. Of the 44 analyzed cytokines, mean levels of sIL-6R in PAT-conditioned medium were found to be significantly higher in the APF groups than in the non-APF group (P = 0.049). In a validation study with a larger number of donors (n = 48), mean sIL-6R levels remained significantly higher in both groups with APF compared to the non-APF group (P = 0.042).

Conclusions

Several radiographic features, such as perinephric fat area and stranding, were found to be pure host-related risk factors for severe APF. sIL-6R secreted from adipose tissues may have utility in predicting the severity of APF in patients undergoing renal surgery. Pure host-related risk factors for APF may predict difficulty during perinephric fat dissection.

Funding

None