| Gallstones form when liquid stored in the gallbladder hardens
into pieces of stone-like material. The liquid, called bile, is
used to help the body digest fats. Bile is made in the liver,
then stored in the gallbladder until the body needs to digest
fat. At that time, the gallbladder contracts and pushes the bile
into a tube—called the common bile duct—that carries it to the
small intestine, where it helps with digestion.
Bile contains water, cholesterol, fats, bile salts, proteins,
and bilirubin. Bile salts break up fat, and bilirubin gives bile
and stool a yellowish color. If the liquid bile contains too
much cholesterol, bile salts, or bilirubin, under certain
conditions it can harden into stones.
The two types of gallstones are cholesterol stones and pigment
stones. Cholesterol
stones are usually yellow-green and are made primarily of
hardened cholesterol. They account for about 80 percent of
gallstones. Pigment stones are small, dark stones made of
bilirubin. Gallstones can be as small as a grain of sand or as
large as a golf ball. The gallbladder can develop just one large
stone, hundreds of tiny stones, or almost any combination
The gallbladder and the ducts that carry bile and other
digestive enzymes from the liver, gallbladder, and pancreas to
the small intestine are called the biliary system.
Gallstones can block the normal flow of bile if they lodge in
any of the ducts that carry bile from the liver to the small
intestine. That includes the hepatic ducts, which carry bile out
of the liver; the cystic duct, which takes bile to and from the
gallbladder; and the common bile duct, which takes bile from the
cystic and hepatic ducts to the small intestine. Bile trapped in
these ducts can cause inflammation in the gallbladder, the
ducts, or, rarely, the liver. Other ducts open into the common
bile duct, including the pancreatic duct, which carries
digestive enzymes out of the pancreas. If a gallstone blocks the
opening to that duct, digestive enzymes can become trapped in
the pancreas and cause an extremely painful inflammation called
gallstone pancreatitis.
If any of these ducts remain blocked for a significant period of
time, severe—possibly fatal—damage or infections affecting the
gallbladder, liver, or pancreas can occur. Warning signs of a
serious problem are fever, jaundice, and persistent pain.
Article provided
by the National Digestive Diseases Information Clearinghouse
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