What are Gallstones and How Do They Form?
Gallstones are pieces of hard solid matter in the gallbladder. Gallstones form when the components of bile (especially cholesterol and bilirubin) precipitate out of solution and form crystals, much as sugar may collect in the bottom of a syrup jar. In general, either cholesterol or bilirubin precipitates out of solution to form stones, but not both. In the United States, almost 80% of patients with gallstones have cholesterol stones. Gallstones may be as small as a grain of sand or as large as a golf ball, and the gallbladder may contain anywhere from one stone to hundreds. Sometimes the gallbladder contains only crystals and stones too small to see with the naked eye. This condition is called biliary sludge. No one knows why some people develop gallstones and others don’t. Any condition that increases the amount of cholesterol in bile increases the risk of stones. Conditions that increase bilirubin in bile increase the risk of pigment (bilirubin) stones. Other factors are important in
