Perinephric Toxic Fat: Impact on Surgical Complexity, Perioperative Outcome, and Surgical Approach in Partial Nephrectomy

INTRODUCTION: To assess influencing factors on perinephric toxic fat (high Mayo Adhesive Probability [MAP] score) and the impact of high MAP scores on surgical complexity, perioperative outcome, and surgical approach in patients with localized renal tumors undergoing open (OPN) and robot-assisted partial nephrectomy (RAPN). METHODS: 698 patients were included in this study. Based on preoperative imaging, adherent perinephric fat (APF) was assessed to define MAP scores. Regression analyses assessed influencing parameters for high MAP scores (≥3), predictors of surgical outcome, and influencing factors on surgical approach. RESULTS: OPN was performed in 331 (47%) patients, and 367 (53%) patients underwent RAPN. Male gender (p < 0.001), age ≥65 (p < 0.001), and BMI ≥27.4 kg/m² (p < 0.001) showed to be significantly influencing factors for the presence of APF. High MAP scores showed to be an influencing factor for a prolonged surgery duration (OR = 1.68, 95% CI 1.22–2.31, p = 0.002) and a significant predictor to rather undergo OPN than RAPN (OR = 1.5, 95% CI 1.05–2.15, p = 0.027). CONCLUSION: Older, male patients with high BMI scores have a higher risk for APF. The presence of APF increases surgery time and may have an impact on decision making regarding the preferred surgical approach.