title: Adherent perinephric fat at minimally invasive partial nephrectomy is associated with adverse peri-operative outcomes and malignant renal histology.
abstract: OBJECTIVE
  To predict adherent perinephric fat (APF) at minimally invasive partial nephrectomy (MIPN) using the Mayo adhesive probability (MAP) score and to determine the impact of MAP score and APF on MIPN outcomes.
  
  
  METHODS
  A total of 245 patients undergoing MIPN were included in the study. The presence of APF was determined through keywords in operating notes, and radiographic data were obtained from preoperative cross-sectional imaging. Posterior fat thickness was measured between the renal capsule and the posterior abdominal wall at the level of the renal vein. Perinephric stranding was graded on a 0-3 severity scale.
  
  
  RESULTS
  The study included 123 men and 122 women, with a median age of 55 years, body mass index of 31.7, tumour size of 2.7 cm and nephrometry score of 6. The median posterior fat thickness was 1.79 cm and MAP score 2.63. In all, 26 patients (10.6%) had evidence of APF at the time of renal surgery. Factors predictive of APF included increasing age (P = 0.001), male gender (P = 0.045), perinephric stranding (P = 0.002), posterior fat thickness (P < 0.001) and MAP score (P < 0.001). APF was associated with adverse pathological and peri-operative outcomes including malignant renal histology (P = 0.04), longer operating time (P = 0.005) and greater estimated blood loss (EBL; P = 0.025).
  
  
  CONCLUSIONS
  Specific clinical and radiographic factors predict APF at MIPN. The presence of APF is associated with adverse peri-operative outcomes including longer operating time and greater EBL. APF was also associated with renal malignancy on final pathology, but further studies are necessary to elucidate the precise underlying mechanism.
authors.affiliation: Department of Surgery, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Kocher
authors.affiliation: Department of Surgery, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Sudhir
authors.initials: S
authors.lastname: Kunchala
authors.affiliation: Department of Surgery, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Reynolds
authors.affiliation: Department of Public Health Sciences, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Erik
authors.initials: E
authors.lastname: Lehman
authors.affiliation: Department of Surgery, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Nie
authors.affiliation: Department of Surgery, College of Medicine, Pennsylvania State University, Hershey, PA, USA.
authors.forename: Jay D
authors.initials: JD
authors.lastname: Raman
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D007431:Intraoperative Complications / Q000209:etiology; D007680:Kidney Neoplasms / Q000473:pathology / Q000601:surgery*; D010535:Laparoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009392:Nephrectomy / Q000379:methods*; D011446:Prospective Studies; D065287:Robotic Surgical Procedures / Q000379:methods; D016896:Treatment Outcome; D047368:Tumor Burden
keywords: Mayo adhesive probability score; adherent perinephric fat; renal cell carcinoma