Gallstones are hard lumps of crystals which develop within the gall bladder. The gall bladder is a small sac-like organ located underneath the liver. The gall bladder is connected to the liver and the intestine via small tubes called bile ducts. Between meal times the gall bladder collects and stores bile from the liver. Bile is a mixture of chemicals which help the digestion and absorption of food. At meal times the gall bladder contracts squeezing bile out into the intestines.
Gallstones develop from the chemicals in bile. They are usually made of cholesterol, but can also be formed from pigments produced by the liver. They may contain calcium salts.
Many factors increase the risk of developing gallstones, these include: