Stones of various sizes and content that form in the gallbladder

  • More common over the age of 40; rare in childhood
  • Twice as common in females
  • Sometimes run in families; more common in people of Asian and white European origin
  • Being overweight and eating a high-fat diet are risk factors

Gallstones occur in about 1 in 10 people over the age of 40, with twice as many women as men being affected. The stones usually occur in the gallbladder, and, in most cases, do not cause symptoms. Gallstones are formed from bile, a liquid that aids digestion and is produced by the liver and then stored in the gallbladder. Bile is made up mainly of the fatty substance cholesterol, pigments, and various salts. A change in the composition of bile may trigger stone formation. Most gallstones are a mixture of cholesterol, calcium salts, and pigments. In about 1 in 5 cases, stones consist of cholesterol only, and in about 1 in 20 cases, stones consist of pigment only. Often, there are many stones, and some can reach the size of a golf ball. Gallstones may run in families, and they are more common in people of Asian and white European origin, for reasons that are unclear.


A gallbladder full of gallstones is visible in this colour-enhanced X-ray. In some people, gallstones are detected only when an X-ray is taken for another purpose.

What are the causes?

There is often no obvious cause for gallstones. However, cholesterol stones are more common in people who are very overweight (see Obesity in adults) and the risk of stones forming may also be greater than normal in people who have a high-fat diet.

Pigment stones may form if there is excessive destruction of red blood cells, as in the disorders haemolytic anaemia and sickle-cell disease. Insufficient emptying of the gallbladder caused by narrowed bile ducts may also increase the risk of gallstones.

What are the symptoms?

Gallstones often cause no symptoms. However, symptoms may occur if one or more stones block the cystic duct (the exit tube from the gallbladder) or the common bile duct (the main bile duct from the liver to the duodenum). A stone that partially or completely blocks the flow of bile will cause attacks known as biliary colic, which cause symptoms that may include:

  • Mild to severe upper abdominal pain.

  • Nausea and vomiting.

Episodes are normally brief and typically occur following a fatty meal, which causes the gallbladder to contract.

Are there complications?

Stones that remain lodged in the bile ducts block the drainage of bile. This can cause severe inflammation or infection of the gallbladder (see Cholecystitis). Blocked bile ducts may also cause jaundice, in which the skin and whites of the eyes become yellow. In addition to jaundice, blockage of the common bile duct may cause inflammation of the pancreas (see Acute pancreatitis).

How are they diagnosed?

Most people only become aware that they have gallstones by chance when an unrelated condition is being investigated. However, if your doctor suspects from your symptoms that you have gallstones, you may have blood tests to check your red blood cell count and cholesterol levels. You may also have imaging tests, such as ultrasound scanning. If a bile duct is found to be blocked, the exact position of the gallstones may be located using a special imaging procedure called ERCP, in which an endoscope (viewing tube) is used to inject a special dye into the bile ducts prior to X-rays being taken, or by an MRI scan.

What is the treatment?

Gallstones that do not cause symptoms need no treatment. If you have mild or infrequent symptoms, adopting a diet that is low in fat may prevent further discomfort. However, if your symptoms are persistent or become worse, you may have your gallbladder removed by conventional surgery or by minimal access surgery (see Having minimally invasive surgery). Removal of the gallbladder usually cures the problem. However, in very rare cases, the stones re-form in the bile duct and may need to be removed by open surgery or during ERCP. The absence of a gallbladder does not usually cause any health problems, and the bile simply drains continuously through a duct directly into the intestines.

Drugs are available that dissolve gallstones made of pure cholesterol, but it may take months or years for the stones to dissolve completely. Occasionally, you may be treated with ultrasonic shock waves (see Lithotripsy), which shatter the stones into tiny pieces so that they pass painlessly into the small intestine and are excreted in the faeces. Use of drugs or ultrasonic shock waves avoids the need for surgery. However, because the gallbladder is still present there is an ongoing risk that further gallstones will form.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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