Gallstones are hardened deposits of digestive fluid that can form in your gallbladder.
As your stomach and intestines digest food, your gallbladder releases bile through a tube called the common bile duct. Your gallbladder is most likely to give you trouble if something blocks the flow of bile through the bile ducts, usually a gallstone. Gallstones form when substances in bile harden. Gallstone attacks usually happen after you eat.
You can reduce your risk of gallstones if you:
Don't skip meals
Lose weight slowly
Maintain a healthy weight
Certain people have a higher risk of developing gallstones than others:
- Women are more likely to develop gallstones than men. Extra estrogen can increase cholesterol levels in bile and decrease gallbladder contractions, which may cause gallstones to form.
- People over age 40 are more likely to develop gallstones than younger people.
- People with a family history of gallstones have a higher risk.
- American Indians have genetic factors that increase the amount of cholesterol in their bile. In fact, American Indians have the highest rate of gallstones in the United States—almost 65 percent of women and 30 percent of men have gallstones.
- Mexican Americans are at higher risk of developing gallstones.
Other factors that affect a person’s risk of gallstones include:
- Rapid weight loss
- Certain intestinal diseases
- Metabolic syndrome, diabetes, and insulin resistance
Imbalances in the substances that make up bile cause gallstones. Gallstones may form if bile contains too much cholesterol, too much bilirubin, or not enough bile salts. Scientists do not fully understand why these imbalances occur. Gallstones also may form if the gallbladder does not empty completely or often enough.
The two types of gallstones are cholesterol and pigment stones:
- Cholesterol stones, usually yellow-green in color, consist primarily of hardened cholesterol. In the United States, more than 80 percent of gallstones are cholesterol stones.
- Pigment stones, dark in color, are made of bilirubin.
Many people with gallstones do not have symptoms. Gallstones that do not cause symptoms are called asymptomatic, or silent, gallstones. Silent gallstones do not interfere with the function of the gallbladder, liver, or pancreas.
If gallstones block the bile ducts, pressure increases in the gallbladder, causing a gallbladder attack. The pain usually lasts from 1 to several hours. Gallbladder attacks often follow heavy meals, and they usually occur in the evening or during the night.
Gallbladder attacks usually stop when gallstones move and no longer block the bile ducts. However, if any of the bile ducts remain blocked for more than a few hours, complications can occur. Complications include inflammation, or swelling, of the gallbladder and severe damage or infection of the gallbladder, bile ducts, or liver.
A health care provider will usually order an ultrasound exam to diagnose gallstones.
Other common imaging tests are:
Computerized tomography (CT) scan
Magnetic resonance imaging (MRI)
Endoscopic retrograde cholangiopancreatography (ERCP)
Health care providers also use blood tests to look for signs of infection or inflammation of the bile ducts, gallbladder, pancreas, or liver.
If gallstones are not causing symptoms, treatment is usually not needed. However, if a person has a gallbladder attack or other symptoms, a health care provider will usually recommend treatment. A person may be referred to a gastroenterologist—a doctor who specializes in digestive diseases—for treatment. If a person has had one gallbladder attack, more episodes will likely follow.
The usual treatment for gallstones is surgery to remove the gallbladder. If a person cannot undergo surgery, nonsurgical treatments may be used to dissolve cholesterol gallstones. A health care provider may use ERCP to remove stones in people who cannot undergo surgery or to remove stones from the common bile duct in people who are about to have gallbladder removal surgery.