16. Cholelithiasis (aetiology and complications) and pathology of the extrahepatic biliary tract

Last updated on March 16, 2019 at 13:17

Introduction

Cholelithiasis refers to the presence of gallstones in the gallbladder, while choledocholithiasis refers to gallstones in the common bile duct. 10-20% of adults in the western countries are currently affected by gallstones, which shows that they are very common and commonly asymptomatic.

Gallstones can be removed by a procedure called ERCP, where a tube is led through the upper GI tract into the biliary tree through the ampulla of Vater. This tube can visualize and remove stones if necessary.

Types and pathogenesis

Two types of stones exist. The most common type is the cholesterol stone, which accounts for 80% of all stones in the west. Bile formation is the only significant pathway for the body to eliminate excess cholesterol, either as free cholesterol or as bile salts. Cholesterol is dissolved in bile. The solution gets supersaturated if the cholesterol concentration exceeds the solubilization capacity of the bile.

Cholesterol won’t crystallize out of the solution until there is a nucleus, a “starting point” that it can precipitate onto. This nucleation process is then followed by growth, as more and more cholesterol precipitate into the nucleus, causing the stone to grow in size. Biliary stasis is also essential for the development of a stone.

The second type of stone is the pigment stone, which is comprised of bilirubin-calcium salts. These usually occur in association with chronic haemolysis, which increases the production of bilirubin.

Cholesterol stones arise exclusively in the gallbladder and are yellowish. Pigment stones may arise anywhere in the biliary tree and are black or brownish.

Risk factors

The risk factors for the two different stones are different. It’s important to keep in mind that up to 80% of people with gallstones don’t have any identifiable risk factors.

For cholesterol stones:

  • 6 Fs
    • Fat (obesity)
    • Female
    • Fertile (multiparity or pregnancy)
    • Forty (above 40 years of age)
    • Fair-skinned (Caucasian)
    • Family history
  • Malabsorption
    • Crohn’s disease

For pigment stones:

  • Chronic haemolytic anaemias
  • Cirrhosis
Complications

Only a minority of people with gallstones are symptomatic. Colicky biliary pain in the right upper quadrant is common.

There are many possible complications of gallstones:

  • Cholecystitis
    • Can lead to gallbladder carcinoma
  • Empyema
  • Choledocholithiasis
  • Ascending cholangitis
  • Fistula formation
  • Bile stone ileus

Cholecystitis is almost always associated with gallstones. It can be acute or chronic. If a gallstone obstructs the neck of the gallbladder or the cystic duct will cholecystitis develop. Chemical irritation due to obstruction of bile outflow lies in the background. Bacterial superinfection may occur, causing the gallbladder to fill with pus and causing empyema. This may require surgical intervention.

The inflammation of the gallbladder in response to gallstone blockage can be chronic as well. These cases have no striking symptoms. The chronic cholecystitis causes the gallbladder to become fibrotic, and the risk for gallbladder carcinoma increases.

Stones may occur in the common bile duct or they may travel there. In any case is there choledocholithiasis, which has much of the same symptoms and complications and cholecystitis. Stones distally to the pancreatic duct may cause pancreatitis.

The bile stasis caused by stones in the biliary tree predisposes to ascending cholangitis, an infection of the biliary tract that may ascend even into the liver.

Tumor

Cholangiocellular carcinoma (CCC) can occur anywhere in the biliary tree, even in the gallbladder (where it is called gallbladder carcinoma) or in the liver (intrahepatic cholangiocarcinoma). This tumor arises from the cholangiocytes that line the bile ducts. It’s often associated with gallstones, which cause chronic inflammation which promotes mutations.

Extrahepatic CCCs cause obstruction of the bile ducts rather quickly, so posthepatic jaundice occurs. This allows diagnosis to be made early. The same can not be said for intrahepatic types, which are discovered late.

If a CCC occurs at the confluence of the right and left hepatic bile ducts, the hilum, is the tumor called a Klatskin tumor.


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15. Tumours and tumorlike conditions of the liver

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17. Acute and chronic pancreatitis. Tumours of the pancreas

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