The cause of bile duct disorders varies, depending on the type of disorder. The cause of several bile duct disorders, including biliary atresia, Alagille syndrome, choledochal cysts (condition in which cysts form in the bile ducts, causing them to be abnormally large) and Caroli disease, is unknown.

Other potential causes and risk factors associated with specific bile duct disorders include the following (listed by type of disorder):

• Gallstones. The exact cause of gallstones is not known, but contributing factors include excess cholesterol and inadequate gallbladder emptying. Risk factors for gallstones include gender (female), obesity, advanced age, family history of gallstones and pregnancy.
  
  
• Primary biliary cirrhosis. Its cause is unknown, but women are affected ten times more frequently than men. It is usually first diagnosed in patients between the ages of 30 and 60.
  
  
• Primary sclerosing cholangitis. Although the exact cause of primary sclerosing cholangitis is not known, it is believed that genetics and immunologic factors play a role. It is more common in men than women and usually starts in patients in their 30s, 40s or 50s.
  
  
• Biliary stricture. These are often caused by surgical trauma to the bile ducts. This causes bile to leak, which can lead to infection or formation of scar tissue. Other causes include blunt injury (e.g., car accident) to the intestine, pancreatitis, gallstones in the bile ducts, primary sclerosing cholangitis and bile duct cancer.
  
  
• Biliary dyskinesia. This disorder is not fully understood, but it may develop after surgery to remove the gallbladder (cholecystectomy). For this reason, it is sometimes called postcholecystectomy syndrome.
  
  
• Bile duct cancer. The exact cause of bile duct cancer is not known, but risk factors include parasite infestation and conditions that result in chronic inflammation of the bile duct.