biliary

Biliary refers to bile and the biliary system, which carries bile from the liver, where it is produced, to the small intestine, where it aids digestion. Bile consists of water, bile acids, cholesterol, phospholipids, bilirubin, electrolytes, and pigments. Bile acids emulsify fats, facilitating digestion and absorption of fat-soluble vitamins.

The biliary system includes the intrahepatic bile ducts within the liver, the extrahepatic common hepatic duct, the common bile duct, the gallbladder, the cystic duct, and the pancreaticobiliary junction at the ampulla of Vater. Bile flows from hepatocytes into bile canaliculi, through ducts to the gallbladder for storage, and is released into the duodenum in response to meals.

Common biliary diseases include cholelithiasis (gallstones) which can block ducts and cause biliary colic or cholecystitis; acute cholangitis from infection of the biliary tree; biliary atresia in infancy; cholestasis; and inflammatory diseases such as primary biliary cholangitis and primary sclerosing cholangitis. Symptoms may include right upper quadrant pain, jaundice, pruritus, nausea, and sometimes fever.

Diagnosis typically involves imaging and laboratory tests. Ultrasound is a common initial test; magnetic resonance cholangiopancreatography (MRCP) provides noninvasive visualization of the biliary tree; endoscopic retrograde cholangiopancreatography (ERCP) is used for diagnosis and treatment. Laboratory markers often show elevated alkaline phosphatase and gamma-glutamyltransferase, with varying bilirubin and transaminase levels.

Treatment depends on the condition. Symptomatic gallstones may require cholecystectomy; biliary obstruction or cholangitis may need biliary drainage, stenting, or ERCP-guided interventions. Antibiotics are used for infection. The prognosis varies by disease and severity, with many biliary conditions manageable with timely diagnosis and appropriate therapy.