In medicine, gallstones (choleliths) are crystalline bodies formed within the body by accretion or concretion of normal or abnormal bile components.
Gallstones can occur anywhere within the biliary tree, including the gallbladder and the common bile duct. Obstruction of the common bile duct is ''choledocholithiasis''; obstruction of the biliary tree can cause jaundice; obstruction of the outlet of the pancreatic exocrine system can cause pancreatitis. Cholelithiasis is the presence of stones in the gallbladder or bile ducts: ''chole-'' means "bile", ''lithia'' means "stone", and ''-sis'' means "process".
A gallstone's size can vary and may be as small as a sand
grain or as large as a golf ball. The gallbladder may develop a single,
often large stone or many smaller ones. They may occur in any part of
the biliary system.
Gallstones have different appearance, depending on their
contents. On the basis of their contents, gallstones can be subdivided
into the two following types:
- ''Cholesterol stones'' are usually green, but are
sometimes white or yellow in color. They are made primarily of
cholesterol, the proportion required for classification as a
cholesterol stone being either 70% (Japanese classification system) or
80% (US system).
- ''Pigment stones'' are small, dark stones made of
bilirubin and calcium salts that are found in bile. They contain less
than 20% of cholesterol. Risk factors for pigment stones include
hemolytic anemia, cirrhosis, biliary tract infections, and hereditary
blood cell disorders, such as sickle cell anemia and spherocytosis.
The proportions of these different types of stone found
varies between samples, and is thought to be affected by the age and
ethnic or regional origin of the patients.
All stones are of mixed content to some extent. Those
classified as mixed, however, contain between 30% and 70% of
cholesterol. In most cases the other majority constituent is calcium
salts such as calcium carbonate, palmitate phosphate, and/or
bilirubinate. Because of their calcium content, they can often be
Also known as "Fake stones," they are sludge-like gallbladder secretions that act like a stone.
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