The bile ducts (BV) are a system of tubes made up of epithelial cells called cholangiocytes that carry bile from the liver, where it is produced, to the gallbladder and intestine, where it is used in the digestive process.
The gallbladder is a small, hollow, pear-shaped organ found in the lower part of the liver that, through a channel called the cystic duct, communicates with the main bile duct. The gallbladder and cystic duct together are defined as the accessory bile duct. Its function is to deposit and concentrate bile, a liquid produced by the liver that helps digest fats. Although by far the most frequent pathology of the gallbladder is gallstones, this organ is not exempt from tumor diseases.
It is possible to distinguish between intrahepatic and extrahepatic bile ducts.
- The intrahepatic bile ducts (IVB) are the system of canaliculi and ducts present within the liver parenchyma (portal spaces), which conduct the bile produced by the hepatocytes (organized into lobules) into gradually larger ducts, up to the right and left hepatic ducts, respectively draining the two functional halves of the liver, right and left.
- The extrahepatic bile ducts (EVBs) are the duct system that extends from the hepatic hilum to the duodenum.
They are formed by the right and left hepatic ducts that flow from the hepatic hilum into the common hepatic duct, which is about 2 cm long. After receiving the cystic duct (from the gallbladder), the common hepatic duct becomes the common bile duct.
The common hepatic duct and common bile duct are known in association as the main bile duct (MPV). The latest anatomical-surgical classification proposed by the Japanese Liver Cancer Study Group (LCSGJ) defines the upper limit of EBV using the portal branches as a reference system (points U and P), while the lower limit is marked from the point where the common bile duct enters the duodenal wall.
The EVB is then divided into two portions, the perihilar and the distal, by means of an ideal line that equally divides the VBP into two halves, superior and inferior, passing approximately at the confluence of the cystic duct with the bile duct.