An understanding of the anatomy of the extrahepatic biliary tree is essential in performing biliary tract surgery. Which of the following statement(s) is/are true concerning biliary ductal anatomy?

b.The common hepatic duct unites with the cystic duct to form the common bile duct

c.An accessory right hepatic duct occurs in 5% of patients

d.A common channel or "Y" configuration of the distal bile duct and pancreatic ducts occur in approximately 70% of patients 

The classic anatomical description of the extrahepatic bile ducts and their arteries is present in only one-third of individuals. The left hepatic duct usually has a longer extrahepatic course than does the right hepatic duct. The common hepatic duct is formed by the union of the right and left hepatic ducts close to the emergence from the liver. The duct passes downward in the superior portion of the hepatoduodenal ligament and lies in front of the portal vein and to the right of the hepatic artery. The common hepatic duct unites with the cystic duct to form the common bile duct. An accessory right hepatic duct occurs in 5% of cases. The cystic duct passes downward, backward, and to the left in the hepatoduodenal ligament and usually unites with the main hepatic duct at an acute angle. Its course and mode of insertion into the common duct is highly variable. The common bile duct is formed by the union of the common hepatic and cystic ducts and is usually about 7 to 9 cm long. The junction of the distal common bile duct and pancreatic duct at the ampulla can take one of three configurations. In approximately 70% of patients, there is a common channel of the bile and pancreatic ducts, thus a "Y" configuration. In approximately 20%, the common channel is nonexistent, and in another 10%, the two ducts enter the duodenum via separate openings.