• Basics

    Gallstones are solid crystals that form in the gallbladder or nearby bile ducts Figure 01. Most gallstones form in the gallbladder, a small pear-shaped organ located in the upper right side of the abdomen, underneath the liver. The gallbladder stores bile, a digestive fluid that makes cholesterol, fats, and some vitamins more easily absorbed by the body.

    Click to enlarge: Anatomy of liver, gallbladder, and ducts

    Figure 01. Anatomy of liver, gallbladder, and ducts

    Cholesterol is the primary element of most gallstones, but gallstones can also form from calcium salts and bile pigments. Cholesterol is a normal component of bile, and usually remains dissolved. However, when the bile becomes oversaturated with cholesterol, small crystals form. These crystals are trapped in mucus within the gallbladder, and gradually grow. Gallstones can be as small as grains of sand or as large as golf balls.

    Gallstones are one of the most common medical conditions in the U.S. Approximately one million people in the U.S. develop gallstones each year, and as many as 500,000 operations are performed annually to remove the gallbladder, usually as a result of gallstone disease.

    Gallstones can cause serious and potentially fatal complications if left untreated.

  • Causes

    Gallstones occur when the liver excretes bile that is excessively rich in cholesterol. The mechanism that predisposes some people to form gallstones is not well-understood. Overproduction of cholesterol due to genetic factors, infrequent emptying of the gallbladder (as during fasting), and infection with certain bacteria have all been identified as potential causes of gallstones.

    Serious symptoms of gallstones result from blockage of the bile duct system. Blockage of the bile duct system allows bacteria to flourish, resulting in severe, potentially life-threatening infection. The infection can spread from the bile ducts to the pancreas and through the blood to other parts of the body.

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