Editing Liver (section)

== '''Biliary system''' ==

* Biliary radicals
** First-order: right and left      CHD
** Second-order: the      next-largest ducts upstream
** Third-order: unusual to see      these on MRCP
** The main duct draining each      Couinaud segment is named after it: B1, B2, B3, etc.
* Each portal pedicle contains     an intra-hepatic bile duct - the terminal branches of the right and left     hepatic ducts. The bile duct branches are usually superior to the portal     vein, with the hepatic artery further inferior.
* Left hepatic bile duct
** Drains segments II, III, and      IV
** Forms from intra-hepatic      ductal branches at the base of the umbilical fissure
** Exposed by dividing the      peritoneum at the base of the quadrate lobe and opening the hilar plate.      The duct is usually the most superficial of the portal triad structures      here.
* Right hepatic bile duct is     formed from:
** Right anterior sectoral duct      (segments V and VIII) - runs vertically
** Right posterior sectoral      duct (VI and VII) - runs in a horizontal and posterior direction,      typically curving around the right anterior duct (Hjortso's crook)
*** This crook places RPSD at       risk when RASD is divided
* Caudate lobe
** Drains through both sides      80%
** Drains through left only 15%
** Drains through right only 5%
* The RHD bifurcates close     upstream from the CHD, into anterior and posterior segmental ducts.     Variable confluence - see diagram below
** Note that 30% of patients      have some right ducts draining into the main left hepatic duct, usually      RPSD - always tie the left duct as far to the left as possible

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