title: The cystohepatic septum: anatomical findings and surgical considerations.
abstract: BACKGROUND
  The cystohepatic septum (CHS) is located at the interface between the cystic duct and the common hepatic duct. Although its presence may have clinical and surgical implications, the CHS has never been morphologically studied.
  
  
  OBJECTIVE
  This study aims to determine the prevalence and anatomic characteristics of the cystohepatic septum.
  
  
  METHODS
  Analytical cross-sectional study of 50 cadaveric dissections was performed. The prevalence and anatomic characteristics of the CHS were analyzed. The cystohepatic junction (CHJ) was characterized from two perspectives. The "external CHJ" was defined as the apparent junction of the cystic duct with the common hepatic duct, as viewed from an extraluminal perspective. The "internal CHJ" was defined as the actual junction of the cystic duct lumen with the common hepatic duct lumen, that is, from the intraluminal perspective. In addition to measuring the length of the CHS, the location of the external and internal CHJ along the length of the extrahepatic biliary tract was classified into three zones (proximal, middle, and distal).
  
  
  RESULTS
  A CHS was identified in 21 cases (42%). The average length was 12 mm. In these 21 cases, the external CHJ was located in the middle zone of the extrahepatic biliary tract in 15 (71%) patients, the proximal zone in 3 (14%), and the distal zone in 3 (14%), while the internal CHJ was located downstream in relation to the length of CHS.
  
  
  CONCLUSIONS
  A CHS of variable length was identified in a large percentage of cadaveric dissections. This finding has important implications for surgical interventions on the biliary tract such as choledochotomy for common bile duct exploration, transcystic bile duct exploration, or bilioenteric anastomosis. The presence of a CHS may also represent an anatomic factor predisposing to Mirizzi's syndrome.
authors.affiliation: Department of Anatomy, University of Buenos Aires (UBA), Buenos Aires, Argentina, lucasnpina@gmail.com.
authors.forename: Lucas Nahuel
authors.initials: LN
authors.lastname: Pina
authors.forename: Agustín
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Guido Antonio
authors.initials: GA
authors.lastname: Valdés
authors.forename: María Luz
authors.initials: ML
authors.lastname: Tartaglia
authors.forename: Alberto Raúl
authors.initials: AR
authors.lastname: Ferreres
mesh_terms: D002102:Cadaver; D003430:Cross-Sectional Studies; D003549:Cystic Duct / Q000033:anatomy & histology* / Q000601:surgery; D006500:Hepatic Duct, Common / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans