title: Difficulty of Laparoscopic Liver Resection: Proposal for a New Classification.
abstract: OBJECTIVE
  We propose an objective and practical classification system to predict difficulty of different laparoscopic liver resections (LLRs).
  
  
  BACKGROUND
  Surgical difficulty is highly subjective and is not influenced only by surgical factors. Consequently, few series have described the degree of difficulty of LLR or attempted to objectively assess the surgical difficulty.
  
  
  METHODS
  From a prospectively maintained database between 1995 and 2015, patients undergoing LLR without simultaneous procedures were selected, and LLR procedures were divided into 3 groups according to scores based on operative time (< or ≥190 minutes), blood loss (< or ≥100 mL), and conversion rate (< or ≥4.2%).
  
  
  RESULTS
  Altogether, 452 LLRs were divided into 3 groups based on their scores. Group I (0 point) included wedge resection and left lateral sectionectomy. Group II (2 points) included anterolateral segmentectomy and left hepatectomy. Group III (3 points) included posterosuperior segmentectomy, right posterior sectionectomy, right hepatectomy, central hepatectomy, and extended left/right hepatectomy. The rates of overall morbidity (groups I, II, and III: 8.4%, 17.3% and 45.7%, respectively, P < 0.001) and major complications (1.1%, 4.0%, and 20.4%, respectively, P < 0.001) increased significantly with a stepwise increase of groups from I to III (P < 0.001).
  
  
  CONCLUSIONS
  This objective and practical classification system allows the stratification of LLR comprising the low (group I), the intermediate (group II), and the high (group III) grades.
authors.affiliation: Department of Digestive Diseases, Institut Mutualiste Montsouris, Université Paris Descartes, Paris, France.|Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Kawaguchi
authors.affiliation: Department of Digestive Diseases, Institut Mutualiste Montsouris, Université Paris Descartes, Paris, France.
authors.forename: David
authors.initials: D
authors.lastname: Fuks
authors.affiliation: Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kokudo
authors.affiliation: Department of Digestive Diseases, Institut Mutualiste Montsouris, Université Paris Descartes, Paris, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Gayet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005602:France / Q000453:epidemiology; D006498:Hepatectomy / Q000145:classification* / Q000379:methods; D006801:Humans; D015994:Incidence; D010535:Laparoscopy / Q000145:classification* / Q000379:methods; D008113:Liver Neoplasms / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D055815:Young Adult