What is a gallstone?

Gallstones are small, pebble-like substances that develop when bile—composed of water, cholesterol, fats, bile salts, proteins and waste—stored in the gallbladder hardens into pieces of stone-like material. Gallstones are relatively common; approximately 10 percent of people older than 40 have gallstones. But most patients will never develop symptoms. “If gallstones are discovered without symptoms, there is a good chance that the gallbladder will not need to be removed,” says UCLA internist Peter Lefevre, MD.

Gallstones are round or oval, smooth or faceted lumps of solid matter found in the gallbladder, the sac under the liver where bile is stored and concentrated. They arise when there is an imbalance among the bile components. Bile is composed of bile salts; bilirubin; cholesterol, phospholipids and fatty acids; water; electrolytes; and other substances. The most common stones are mixed, containing cholesterol and inorganic salts of calcium.

Gallstones are solid deposits of cholesterol or calcium salts within the gallbladder that form from the bile produced by your liver. While they can be present without causing any symptoms, they are also associated with bouts of nausea, vomiting and intermittent sharp pain in the upper middle or upper right abdomen (sometimes under the right rib cage). The pain may shift to the back or right shoulder blade and may be brought on by foods high in fat.

Gallstones also can become trapped in the neck of the gallbladder, which results in persistent pain and fever, especially if the gallbladder becomes infected (pain that lasts longer than just a few hours is a red flag for infection). Rarely, gallstones can get out of the gallbladder and enter and block the bile dua (which leads from the liver to the small intestine), causing more severe abdominal pain and possibly jaundice (a yellow tinge to the skin and the whites of the eyes), or block the duct leading to the pancreas, causing a condition called pancreatitis.

Gallstones form when substances in bile harden. Your gallbladder is a small organ located in the upper right abdomen, close to your liver. It stores a digestive fluid called bile, which flows into your small intestine. Bile helps your body digest fats. Gallstones may stay in the gallbladder, or may move into the bile ducts; either way they can cause pain in your upper abdomen that may last up to 12 hours, and may lead to complications such as infection.

Gallstones form when bile, stored in the gallbladder, hardens, becoming stone-like. A slowing of gallbladder emptying and an excessive amount of cholesterol, bilirubin (bile pigment) or bile salts in the bloodstream may result in gallstones. There are two types of gallstones: cholesterol stones, which comprise about 80 percent of all gallstones, and pigment stones.

Gallstones are a risk factor for gallbladder cancer and cholangiocarcinoma (bile duct cancer), which are rare but are increasing in frequency. This increase may be due to a rise in obesity rates, a risk factor for gallstones. If a gallstone obstructs a bile duct, it can lead to a life-threatening infection of the bile ducts, liver, or pancreas.

Gallstones are small crystal masses that are formed in the gallbladder. Learn more about gallstones in this video with Rick Kline, MD, Trauma Medical Director at Regional Medical Center of San Jose.