Generally, bile ducts I, II, III and IV constitute the left hepatic duct
, and segmental ducts V, VI and VII form the right hepatic duct.
Intrabiliary rupture occurs in the right hepatic duct (55-60% cases), left hepatic duct
(25-30% cases), hepatic duct junction, common bile duct (CBD), or cystic duct (8-11%); perforation into the gallbladder may be observed in 5-6% of cases.
In one patient with a complex centrally located cyst in whom the left hepatic duct
communicated with the cyst cavity, a biliary-enteric reconstruction with a Roux-en-Y loop was performed.
Bismuth-Corlette perihilar cholangiocarcinoma classification system (1) Type I Involves common hepatic duct only Type II Involves confluence of the primary hepatic ducts Type IIIa Extends from the bifurcation up the right hepatic duct Type IIIb Extends from the bifurcation up the left hepatic duct
Type IV Extends bilaterally from the bifurcation of the common hepatic duct or multifocal involvement Table 3: Contraindications to curative surgery (1) Medical Contraindications A.
Type 1: Normal anatomy; right hepatic duct and left hepatic duct
(LHD) merge to form the common hepatic duct (CHD).
Vakili et al  noticed that caudate process duct drains into right hepatic duct (85%) and left part of caudate lobe into left hepatic duct
 reported two intraoperative complications: one patient suffered bleeding from a torn branch of the main portal vein during node dissection that induced conversion to laparotomy; the other case is an injury of the left hepatic duct
during LLA treated with intracorporeal repair and T-tube insertion with full postoperative recovery.
Furthermore, Nakamura's operative series report the supraportal RPSBD to be most common in BD variant type I (65%, the classic form where the RPSBD and the anterior sectional BD join to form a single right hepatic duct), type II (9.2%, the RPSBD joins the confluence, forming trifurcation), and type IV (15.8%, the RPSBD joins the left hepatic duct
), whereas the infraportal RPSBD is reported to be most common in type III (8.3%) and that of the combination in type V (1.7%) .
OCH usually affects the left hepatic duct
, especially the left lateral segmental duct, in the early course of the disease for unknown reason , although stones may be present in the right and left hepatic lobes and the extrahepatic biliary tree.
Of note, in all three cases, the right and left hepatic duct
joined to form the common bile duct that took a cranial course to enter the duodenal ampulla in the usual location.
The variation of right posterior branch draining into the left hepatic duct
was reported with a rate of about 4.15%-19.1% of the population.
Common bile duct (CBD) was most commonly involved in 50% of cases followed by confluence of right and left hepatic duct
and pancreas in 13.33%.