Gallstones are hardened deposits of digestive fluid that can collect in the gallbladder. The gallbladder is a small organ in the abdomen that holds bile before it is released into the small intestine as part of the digestive process. When they form, gallstones can range from as small as a grain of sand to as large as a golf ball. People with gallstones may have only one, or they may have many.
According to the National Institutes of Health, an estimated 20 million Americans have gallstones. Most do not even know it. Gallstones, or solid deposits of cholesterol or other crystals that form in the gallbladder, often produce no symptoms. When symptoms do present, they often lead to pain in the abdomen and nausea, often after meals.