Gallstones are supersaturated, pebble-like deposits of bile inside the gallbladder. They can be as small as a grain of sand or as big as a golf ball and can occur as a single stone or as a collection of stones in a combination of sizes. There are two types of gallstones — cholesterol stones, which account for 80 percent of gallstones, and pigment stones, which are composed of bilirubin, a chemical found in bile, according to the National Institutes of Health.

Gallstones occur in as many as 60 to 70 percent of American Indians and 10 to 15 percent of white adults in developed countries, according to a review conducted by University of Calgary researchers. It is also more common in women, people over the age of 40 and people with a family history of gallstones.


Bile is made in the liver and it is stored in the gallbladder until it is transported to the small intestine, where it helps with digestion. Gallstones occur when there's an imbalance in the bile transportation process. Cholesterol stones can form when bile contains too much cholesterol, too much bilirubin or not enough bile salts, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDKD). They can also occur when the gallbladder does not empty into the common bile duct completely or often enough. Women are twice as likely as men to develop gallstones since excess estrogen from pregnancy, hormone replacement therapy, and birth control pills may increase cholesterol levels and decrease gallbladder movement, which can facilitate gallstones.

Black pigment stones usually consist of bilirubin polymers and calcium carbonate, and they rarely contain cholesterol. These stones are mostly found in the gallbladder, and can develop as a result of liver damage, alcoholic liver disease, hemolytic anemia and old age, according to the University of Maryland. Brown pigment stones usually consist of calcium bilirubinate, fatty acids and small amounts of cholesterol. These are usually found in the bile duct and they are almost always associated with bile infections, inflammations and occasionally, parasitic infestations in the liver.

Diagnosis & Tests

The majority of people with gallstones are asymptomatic. Therefore, gallstones are often discovered during routine x-ray, abdominal surgery or other medical procedures, according to the NIH.

Occasionally, gallstones can cause prolonged discomfort and cramps as the stones wind down the bile duct, creating a blockage and increasing the pressure in the gallbladder. These sudden occurrences are known as gallbladder “attacks” and they often happen during the night or after a fatty meal, according to NIDDKD. When this occurs, the doctor will order an ultrasound exam to look for gallstones. Although ultrasound is the most sensitive and specific test for gallstones, the doctor may also order a CT scan if the symptoms are more serious, since the CT scan can also detect complications such as a ruptured or infected gallbladder or bile duct.

Hepatobiliary iminodiacetic acid (HIDA) scan, magnetic resonance imaging (MRI) or endoscopic retrograde cholangiopancreatography (ERCP) are some other imaging techniques that can be used to locate the gallstones, according to the Mayo Clinic. In the case of ERCP, the doctor can simultaneously locate and remove the gallstones using the endoscope.

Treatments & Medications

Surgery may not be needed unless there are symptoms, according to the NIH. However, people with frequent gallbladder attacks may opt to have their gallbladder surgically removed. The procedure is known as cholecystectomy and it can be performed using a laparoscope and a miniature video camera. The process is minimally invasive and most patients require only an overnight stay at the hospital, according to the NIDDKD.

Laparoscopic cholecystectomy is often preferred over open cholecystectomy, which requires a 5- to 8-inch incision across the abdomen and results in longer hospital stays and recovery time. Open surgery accounts for about 5 percent of gallbladder operations, and it is usually done if the gallbladder has severe inflammation, infection, or scarring from other operations, according to the NIDDKD.

In rare and special situations, such as when a patient has a serious medical condition preventing surgery, medications may be taken to dissolve gallstones. The procedure is limited to small cholesterol stones and may require months or years of treatment to fully dissolve all the gallstones, according to the Mayo Clinic.


Gallstones occur more frequently in people at two opposite ends of the weight spectrum — those who are overweight or obese, and those who fast or lose a lot of weight quickly. In addition, research published in the journal Gut in 2004 suggests that high intake of carbohydrate, a fluctuating glycaemic load and glycaemic index increase the risk of symptomatic gall stone disease in men. Therefore, it is important to adopt a healthy diet and stick to regular meal times. Regular exercise and, if necessary, cholesterol medication, can also help regulate cholesterol levels and reduce the likelihood of gallstones.