Gallbladder

The gallbladder is a small, pear-shaped organ located on the underside of the liver. It stores and concentrates bile, a digestive fluid produced by the liver. The gallbladder has a fundus, body, and neck, and is connected to the biliary system by the cystic duct. The cystic duct joins the common hepatic duct to form the common bile duct, which delivers bile to the duodenum via the sphincter of Oddi. Bile is released when fatty chyme enters the small intestine, in response to cholecystokinin.

Functionally, the gallbladder concentrates bile by absorbing water and electrolytes and then contracts to eject bile during digestion. Bile aids fat digestion through emulsification and contains bile acids, cholesterol, phospholipids, and bilirubin. The organ typically holds about 30 to 50 milliliters of bile.

Common gallbladder diseases include cholelithiasis (gallstones) formed from cholesterol or bilirubin, and cholecystitis, usually due to stone obstruction or infection. Biliary colic refers to episodic pain from gallbladder contraction against a stone. Rarely, gallbladder cancer occurs.

Diagnosis usually begins with abdominal ultrasound. Blood tests may indicate inflammation or cholestasis. Additional imaging such as HIDA scan, MRCP, or ERCP can assess gallbladder function and the biliary tree.

Treatment depends on the condition. Asymptomatic stones may be observed, while symptomatic stones and cholecystitis are commonly treated with cholecystectomy, often performed laparoscopically. In selected cases, ursodeoxycholic acid can be used to dissolve cholesterol stones.