Adherent perinephric fat affects perioperative outcomes after partial nephrectomy: a systematic review and meta-analysis.

To investigate the association of adherent perinephric fat (APF) with perioperative outcomes, we conducted a systematic review and meta-analysis of the literature to clarify the impact of APF in patients undergoing partial nephrectomy. A systematic literature search using the Medline, Scopus, and Cochrane databases was performed in April 2019 and updated in November 2019 to identify studies investigating the effect of APF on perioperative outcomes in patients treated with partial nephrectomy with the aim of evaluating its impact on intraoperative, postoperative and oncological outcomes. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the included studies. A total of 1534 patients in nine nonrandomized, observational studies met our inclusion criteria. Patients with APF were significantly older (p = 0.0001), had a higher BMI (p = 0.0001) and were predominately male (p = 0.003). APF was associated with a higher operative time (p = 0.001) and higher blood loss (p = 0.002). No significant impact of APF was found in terms of postoperative complications, positive margins or length of stay. APF was also found to be associated with malignant renal histology of RCC on final pathology (p = 0.005). APF was associated with some adverse perioperative outcomes, especially a prolonged operating time and higher blood loss. In addition, APF was also associated with underlying renal malignancy, but the precise causal mechanism requires further exploration.