title: Fusion of the planes of the liver: an anatomic entity merging the midplane and the left intersectional plane.
abstract: BACKGROUND
  Alignment of the gallbladder fossa and the round ligament may be associated with an almost unknown portal vein branching anomaly.
  
  
  METHODS
  Ultrasonographic imaging allowed detection of this anomaly, which we characterized as fusion of the planes of the liver. When appropriate, additional specific radiologic examinations were performed (CT scanner supplemented with a three-dimensional reconstruction, a biliary cartography, or an angiography). Surgical consequences were studied from this series and from the literature.
  
  
  RESULTS
  Seven patients (0.5%) had the following criteria: 1) round ligament, gallbladder fossa, and termination of the portal vein occurring in the same plane; 2) typical portal vein branching, including a right posterior branch, left branches, and a main medial branch terminated by the Rex's recessus; 3) two main hepatic veins without a significant middle hepatic vein; and 4) absence of the horizontal part of the left hepatic duct. Fusion of the planes may have been involved in two cases of iatrogenic bile duct injury and contraindicated a tumor resection and a right-liver donation. A review of the literature revealed that lack of recognition of the fusion of the planes led to a high proportion of surgical iatrogenic injury. Fusion of the planes could result from incomplete development of the central part of the liver, in agreement with embryologic knowledge.
  
  
  CONCLUSIONS
  Knowledge of the fusion of the planes by hepato-biliary surgeons is important. This anomaly may lead to serious complications if it remains undetected during liver resection or bile duct surgery.
authors.affiliation: Service de Chirurgie Digestive et Transplantation Hépatique, Groupe hospitalier Pitié-Salpêtrière, Paris, France. eric.savier@psl.ap-hop-paris.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Savier
authors.forename: Jacques
authors.initials: J
authors.lastname: Taboury
authors.forename: Olivier
authors.initials: O
authors.lastname: Lucidarme
authors.forename: Kumiko
authors.initials: K
authors.lastname: Kitajima
authors.forename: Mehdi
authors.initials: M
authors.lastname: Cadi
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Vaillant
authors.forename: Laurent
authors.initials: L
authors.lastname: Hannoun
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008099:Liver / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008107:Liver Diseases / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography