The gallbladder is an organ, located just under the liver, that stores the bile the liver makes. Gallstones are small masses of crystallized bile that form in the gallbladder. A gallstone's size can range from similar to a grain of sand to the size of a golf ball, according to the National Digestive Diseases Information Clearinghouse. Many people do not have symptoms associated with gallstones unless the stones lodge in the bile duct. Risk factors for developing gallstones include pregnancy, obesity, increased age and a family history of the problem. Several types of stones may form, and treatment includes surgical removal of the gallbladder.
Cholesterol Stones
The majority of gallstones are cholesterol stones, which account for more than 85 percent of all gallstones in the United States, according to the Merck Manual. High cholesterol diets increase the amount of cholesterol found in the bile, which the liver produces to aid in digestion of fat. The increased cholesterol crystallizes, then forms gallstones inside the gallbladder. Cholesterol stones are a yellowish-green color. These gallstones grow slowly and increase only a couple of millimeters each year. The stones may stay in the gallbladder for years before they cause symptoms.
Black Pigment Stones
Black pigment stones are small, hard salt compounds, caused by too much bilirubin in the bile. Bilirubin is the byproduct of the liver breaking down red blood cells. Risk factors for developing black pigment gallstones include liver disease caused by alcoholism and advanced age. An increase in these salts begins to form gallstones. These stones appear as black in color.
Brown Pigment Stones
Brown pigment gallstones develop from an increase in bilirubin and other fatty acids in the gallbladder. These stones are greasy and soft, according to the Merck Manual. The brown pigment stones most often occur during a parasite infestation or during an infection or inflammation of the liver or gallbladder. Unlike black pigment stones or cholesterol stones, brown pigment stones usually develop in the bile ducts and not in the gallbladder. This increases the chance that the stones will lodge in the ducts or cause an increased risk of infection in the liver and gallbladder.
