Gallstones are collections of crystals in the gallbladder or the bile ducts (biliary tract). When gallstones are in the gallbladder, the condition is called cholelithiasis; when gallstones are in the bile ducts, the condition is called choledocholithiasis.

Gallstones are more common in women and in certain groups of people, such as Native Americans. The risk factors for gallstone formation include old age, obesity, a Western diet, and a genetic predisposition. In the United States, 20 percent of the people over age 65 have gallstones, but most never experience problerms. Each year, more than half a million people have their gallbladder surgically removed-most of them doing so because gallstones have caused

problems.

The major component of most gallstones is cholesterol, though some are made up of calcium salts. Bile contains large amounts of cholesterol that usually remains liquid. When bile becomes oversaturated with cholesterol, however, the cholesterol may become insoluble and precipitates out of the bile.

Most gallstones form in the gallbladder. Most gallstones in the bile ducts travel there from the gallbladder. Stones may form in a bile duct when bile backs up because a duct has narrowed abnormally or after the galltbladder has been removed.

Gallstones in the bile ducts can lead to a severe or life-threatening infection of the bile ducts (cholangitis), the pancreas ( pancreatitis), or the liver. When the bile duct system is obstructed, bacteria can flourish and quickly establish infection in the ducts. The bacterit may spread to the bloodstream and cause infections elsewhere in the body.

责任编辑：admin