Lumps of solid matter found in the gallbladder, or in the bile ducts. Gallstones are composed mainly of cholesterol and bile pigments from the breakdown of red blood cells. They develop when there is a disturbance in the chemical composition of bile. Gallstones are rare in childhood and become increasingly common with age. Women are affected more than men. Risk factors include a high-fat diet and being overweight. Most gallstones cause no symptoms. When symptoms do occur, they often begin when a stone gets stuck in the duct leading from the gallbladder, causing biliary colic and nausea. Gallstones may cause indigestion and flatulence. Possible complications are cholecystitis and bile duct obstruction. Diagnosis is by ultrasound scanning, X-ray oral cholecystography, or cholangiography. Stones that are not causing symptoms are usually left alone. In other cases, the gallbladder and stones may be removed by cholecystectomy. Ultrasonic shock waves (see lithotripsy) are sometimes used to shatter stones; the fragments pass into the bowel and cause no further problems. Drugs such as chenodeoxycholic acid or ursodeoxycholic acid can dissolve some stones if given over a period of months.


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