Once in the intestine, bile helps to digest and absorb the fats from food that has been broken down by enzymes secreted from the pancreas and the intestine. Gallstones are clumps of solid material that form in the bile stored in the gallbladder. There are two major types of gallstones - cholesterol stones and pigment stones. Cholesterol stones are composed primarily of cholesterol, and they account for about 80 percent of gallstones in the United States. Pigment stones, which account for other 20 percent of gallstones are composed of bile pigments such as bilirubin, and other substances such as calcium, which are found in the bile.
Gallstones can vary in size.
They can be as small as a grain of sand or as big as an egg. The gallbladder may develop a single, often large, stone or many smaller ones, even several thousand. Small stones can move into the bile ducts and become lodged there, blocking the flow of bile and causing pain and jaundice. Larger stones can block the outlet from the gallbladder and cause steady, sharp pain when the gallbladder tries to empty. Gallstones form when certain chemicals in the bile, either cholesterol or bile pigments, start to clump together.