Gallstones are lumps of solid material that form in the gallbladder. They usually look like small stones or gravel and can be as small as sand or as large as pebbles, sometimes filling the gallbladder, and may take years to grow. The most common ones are made up of cholesterol, which is a type of fat. Others are known as pigment stones and consist of calcium and red blood cells, which have broken down and solidified.
The gallbladder is a small pear shaped pouch about three to six inches long. It is tucked just under the liver below the right rib cage and is connected to the intestine and liver by small tubes called bile ducts. Bile ducts carry bile, a yellow-green fluid produced by your liver which contains waste products and chemicals to aid digestion. It plays a central role in helping the body digest fat. Bile acts as a detergent, breaking the fat into very small droplets so that it can be absorbed from food in your gut. It also makes it possible for your body to take up the fat-soluble vitamins A, D, E and K from the food passing through the gut. Bile is concentrated and stored in the gallbladder ready for use and is only released when we eat food.
Approximately one in ten people will develop gallstones or another gallbladder disease. It is not fully understood why some people have them and others don't but gallstones are more common in the following groups of people:
- Overweight women
- Women who have been pregnant
- People who have recently lost weight.
What are the effects of gallstones?
Many people with gallstones have no symptoms and are unaware they have them until the stones show up in tests performed for another reason. When symptoms do develop it is usually because the gallbladder wall becomes inflamed or because the stones have moved out of the gallbladder and blocked the tube connected to the intestine, causing pain, jaundice and fever.
The smaller the stone, the more able it is to travel about within the bile duct system. Stones can become lodged in the outlet of the gallbladder and cause recurrent painful attacks known as biliary colic. Frequent attacks can cause inflammation and scarring of the gallbladder known as chronic cholecystitis.
If gallstones leave the gallbladder they may cause other complications such as jaundice and cholangitis (inflammation of the bile ducts) which occurs when the flow of bile from the liver is blocked and the bile becomes infected. Stones which pass from the bile duct into the intestine can also temporarily obstruct the flow of digestive juices from the pancreas resulting in pancreatitis.