Ductus Choledochus: Structure, Function & Diseases

Bile juice is formed in our liver. This bile is needed for the process of fat digestion and is transported to the duodenum through various ducts.

What is the choledochal duct?

The term “duct” is the Latin term for duct. The word “choledochus” describes the function of the anatomical structure in the digestive tract: “receiving bile.” The choledochal duct is also called the common bile duct or great bile duct. It belongs to the area of extrahepatic bile ducts. These are the bile ducts that are located outside the liver.

Anatomy and structure

The two lobes of the liver contain a number of small bile ducts that eventually join with the right hepatic duct (right duct) and the left hepatic duct (left duct). The two bile ducts join to form a common very short bile duct, the ductus hepaticus communis. A duct coming from the gallbladder joins the ductus hepatis communis. The further course of the united right and left bile duct leading out of the liver is called the ductus choledochus by the anatomy from the union with the ductus cysticus. The common bile duct runs above the duodenum in the direction of the pancreas. The pancreas also produces digestive juices. They are transported out of the pancreas via an excretory duct (ductus pancreaticus). The ductus choledochus passes behind the head of the pancreas and is closely intertwined with the tissues of the digestive organ in the area of the pancreas. Finally, the choledochal duct passes behind the duodenum and continues within the intestinal wall. The integration of the choledochal duct into the intestinal wall creates a fold-up of mucosa called the plica longitudinalis duodeni. Usually, at the end of the longitudinal mucosal fold, the ductus choledochus unites with the pancreatic duct (ductus pancreaticus). But this union is not present in all people. When it is created, a bulge forms at the site of union of the two ducts, which in anatomy is called the ampulla hepatopancreatica. The duct from the pancreas and the large bile duct unite and open into the intestinal tube of the duodenum. The point of entry is the papilla duodeni major. The bile ducts, and therefore the common bile duct, have smooth muscle. In addition to the muscular layer, the choledochal duct has connective tissue consisting of collagenous and elastic fibers. Inside the common bile duct, the wall is covered with mucosa containing glands that secrete a secretion. This secretion gives the bile duct inside a high lubricity. This allows the bile to flow more easily. The ductus choledochus is between six and eight centimeters long and the approximate thickness of a pencil.

Function and tasks

The function of the choledochal duct is to transport bile from the liver to the duodenum. There it is needed for the digestive process. In the section immediately before entering the duodenum, the ductus choledochus, united with the ductus pancreaticus, consists of smooth muscle arranged in a ring shape. This structure has additional coils as in a spiral. The area is called the sphincter oddi. The function of the sphincter oddi is to be able to open and close the entry site as needed. During an active digestive process in the duodenum, the sphincter oddi is open and allows bile and digestive secretions from the pancreas to enter the intestine. During periods of rest, the digestive juices remain in the choledochal duct. The annular sphincter prevents them from flowing into the intestinal tube.

Diseases

During the formation of bile, gallstones may form. These stones usually collect in the gallbladder. However, it is also possible for one or more gallstones to move into the choledochal duct. Obstruction of the common bile duct by stones is a condition (choledocholithiasis) that can have serious consequences. The bile no longer reaches the duodenum for the digestive process. Jaundice may develop. The congestion of bile leads to inflammation and life-threatening liver failure.Patients may present with no symptoms at all, depending on the number and size of the calculi, but they may also suffer from severe cramping pain. In addition, dizziness, vomiting, and a feeling of fullness and pressure in the epigastrum may occur. Gallstones in the choledochal duct and other bile ducts can be visualized with ultrasound or magnetic resonance imaging. During ultrasound examination, a probe is inserted through the oral cavity into the digestive tract to the intestine. If imaging confirms the suspicion of choledochal duct obstruction, an endoscopic surgical procedure is used to attempt to remove the calculi from the choledochal duct (endoscopic retrograde cholangiopancreatography). Constrictions or occlusions within the choledochal duct can also be caused by tumors. Cholangiocarcinoma is a malignant tumor of the bile ducts. It can also affect the choledochal duct. The tumor mass can block the flow path in the bile duct. Other tumors that press on the large bile duct in the abdomen can also lead to bile outflow obstruction. Unless the tumor can be completely removed by surgery, bile duct cancer is incurable. Nevertheless, attempts are made to contain possible cancer growth in the choledochal duct with chemotherapy and radiation. Other procedures to treat bile duct carcinoma are still in the research phase.

Typical and common gallbladder diseases

  • Gallstones
  • Gallbladder inflammation
  • Gallbladder cancer and bile duct cancer
  • Biliary colic
  • Cholestasis