Types of gallstones and causes:
- Cholesterol stones
- Pigment stones
- Mixed stones – the most common type. They are comprised of cholesterol and salts.
Cholesterol stones are usually yellow-green and are made primarily of hardened cholesterol. They account for about 80 percent of gallstones. Scientists believe cholesterol stones form when bile contains too much cholesterol, too much bilirubin, or not enough bile salts, or when the gallbladder does not empty as it should for some other reason.
Pigment stones are small, dark stones made of bilirubin. The exact cause is not known. They tend to develop in people who have cirrhosis, biliary tract infections, and hereditary blood disorders such as sickle cell anaemia in which too much bilirubin is formed.