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PH-GI10

Gallstones and biliary obstruction

How bile is made, stored and released, why cholesterol crystallises into stones in some gallbladders, and how a stone blocking the cystic duct or the bile duct causes colic, an inflamed gallbladder, jaundice or a dangerous infection.

By the end, you can

  • Describe the biliary tree and how bile is stored, concentrated and released.
  • Explain how cholesterol supersaturation, stasis and nucleation form gallstones.
  • Distinguish biliary colic from acute cholecystitis by mechanism.
  • Explain how a stone in the bile duct causes obstructive jaundice with pale stools and dark urine.
  • Explain why cholangitis and gallstone pancreatitis are emergencies.
  • Recognise the classic stones and gallbladder appearances and the tests that locate a stone, and explain how cholecystectomy, ERCP, antibiotics with drainage and ursodeoxycholic acid act on the mechanism.

What it is

Gallstones (cholelithiasis) are solid deposits that form in the gallbladder, mostly from cholesterol. Most never cause symptoms. When a stone blocks the cystic duct it causes biliary colic or acute cholecystitis; when it passes into the bile duct (choledocholithiasis) it can cause obstructive jaundice, cholangitis or pancreatitis.

2 types to tell apart
Cholesterol stones
The majority in Western countries; form when bile carries more cholesterol than it can dissolve.
Pigment stones
Black stones from excess bilirubin in haemolytic disease or cirrhosis; brown stones form in infected bile ducts.

Normal function

Making, storing and releasing bile

Hepatocytes secrete bile: water, bile salts, phospholipid (lecithin), cholesterol and conjugated bilirubin. It drains through the and into the .

Between meals, the sphincter at the duodenal end stays closed and bile backs up through the into the , which concentrates it by absorbing water. After a fatty meal, cholecystokinin makes the gallbladder contract and the sphincter relax, sending bile down the into the duodenum.

Cholesterol does not dissolve in water; it is kept in solution in mixed micelles with bile salts and lecithin. In the gut, bile salts emulsify fat for digestion, and most are reabsorbed in the terminal ileum and recycled to the liver.

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