Evaluation of factors predicting adherent perinephric fat in laparoscopic retroperitoenal partial nephrectomy.

Background: Adherent perinephric fat (APF) represents a clinical situation, which increases the complexity of renal surgery. We aimed to elucidate the common characteristics of patients with APF and to evaluate the extent of outcome differentiation depending on the presence of APF.

Methods: We made a retrospective review of a prospectively maintained database of patients who underwent laparoscopic retroperitoneal partial nephrectomy for a localized renal tumor at our institution from May 2010 to January 2022. 238 patients were included in this study. Demographic, intraoperative, postoperative data and characteristics and comorbidities of all patients were evaluated. Radiographic data (tumor size, localization, side, exophytic rate, perinephric fat density [PFD]) were determined from preoperative contrast-enhanced abdominal computed tomography imaging studies. Adherent perinephric fat was classified intraoperatively by the operating surgeon. The patients were divided into two groups as the APF group and the non-APF group and predictors causing APF were investigated.

Results: Intraoperative and postoperative complication rates were higher in the APF group, but the difference between intraoperative complication rates, operation duration and amount of bleeding were statistically significant. (11.6% vs. 5.9%, p = 0.033; 130 vs. 120 min, p = 0.024; 60 vs. 30 cc, p = 0.016, respectively). The most common complications were conversion to open surgery due to failure of dissection of the tumor and bleeding requiring intraoperative transfusion in the groups. On multivariable analysis using stepwise regression model, we identified male gender (OR = 3.328; 95% Cl = 1.552-7.133; p = 0.002), PFD>-100.4 Hounsfield Unit (HU) (OR = 3.24; 95% Cl = 1.549-6.777; p = 0.002) and presence of diabetes mellitus (DM) (OR = 2.513; 95% Cl = 1.192-5.299; p = 0.015), as predictor of APF.

Conclusion: Male gender, presence of DM and PFD>-100.4 HU are predictors of APF. This endpoint is promising for application in gaining knowledge preoperatively about the dissection difficulty level.