Gallstones

Gallstones facts
•Gallstones are "stones" that form in the gallbladder or bile ducts.
•The common types of gallstones are cholesterol, black pigment, and brown pigment.
 •Cholesterol gallstones occur more frequently in several ethnic groups and are associated with female gender, obesity, pregnancy, oral hormonal therapy, rapid loss of weight, elevated blood triglyceride levels, and Crohn's disease.
 •Black pigment gallstones occur when there is increased destruction of red blood cells, and brown pigment gallstones occur when there is slow flow and infection of bile.
•The majority of gallstones do not cause symptoms.
 •The most common symptoms of gallstones are biliary colic and cholecystitis. Gallstones do not cause intolerance to fatty foods, belching, abdominal distention, or gas.
 •Complications of gallstones include cholangitis, gangrene, jaundice, pancreatitis, sepsis, fistula, and ileus.
 •Gallbladder sludge is associated with symptoms and complications of gallstones; however, like gallstones, sludge usually does not cause problems.
•The best single test for diagnosing gallstones is transabdominal ultrasonography. Other tests include endoscopic ultrasonography, magnetic resonance cholangio-pancreatography (MRCP), cholescintigraphy (HIDA scan), endoscopic retrograde cholangio-pancreatography (ERCP), liver and pancreatic blood tests, duodenal drainage, oral cholecystogram (OCG), and intravenous cholangiogram (IVC).
 •Gallstones are managed primarily with observation (no treatment) or removal of the gallbladder (cholecystectomy). Less commonly used treatments include sphincterotomy and extraction of gallstones, dissolution with oral medications, and extra-corporeal shock-wave lithotripsy (ESWL). Prevention of cholesterol gallstones also is possible with oral medications.
 •Symptoms of gallstones should stop following cholecystectomy. If they do not, it is likely that gallstones were left in the ducts, there is a second problem within the bile ducts, or there is sphincter of Oddi dysfunction.
 •Continuing research is directed at uncovering the genes that are responsible for the formation of gallstones.

What are gallstones?
Gallstones (often misspelled as gall stones, or gall stone) are stones that form in the gall (bile) within the gallbladder. (The gallbladder is a pear-shaped organ just below the liver that stores the bile secreted by the liver.)
•Bile is a watery liquid made by the cells of the liver that is important for digesting food in the intestine, particularly fat.

•Liver cells secrete the bile into small canals within the liver.

•The bile flows through the canals and into larger collecting ducts within the liver (the intrahepatic bile ducts).

•The bile then flows through the intrahepatic bile ducts out of the liver and into the extrahepatic bile ducts-first into the hepatic bile ducts, then into the common hepatic duct, and finally into the common bile duct.

From the common bile duct, there are two different directions that bile can flow.
•The first direction is the common bile duct and into the intestine where the bile mixes with food and promotes digestion of food.

•The second direction is into the cystic duct, and from there into the gallbladder (often misspelled as gall bladder).
Once in the gallbladder, bile is concentrated by the removal (absorption) of water. During a meal, the muscle that makes up the wall of the gallbladder contracts and squeezes the concentrated bile in the gallbladder back through the cystic duct into the common duct and then into the intestine. (Concentrated bile is much more effective for digestion than the un-concentrated bile that goes from the liver straight into the intestine.) The timing of gallbladder contraction-during a meal-allows the concentrated bile from the gallbladder to mix with food.
Gallstones usually form in the gallbladder; however, they also may form anywhere there is bile; in the intrahepatic, hepatic, common bile, and cystic ducts.
Gallstones also may move about in the bile, for example, from the gallbladder into the cystic or common duct.


What causes gallstones?
Gallstones are common; they occur in approximately 20% of women in the US, Canada and Europe, but there is a large variation in prevalence among ethnic groups. For example, gallstones occur 1 ½ to 2 times more commonly in Scandinavians and Mexican-Americans. Among American Indians, gallstone prevalence reaches more than 80%. These differences probably are accounted for by genetic (hereditary) factors. First-degree relatives (parents, siblings, and children) of individuals with gallstones are 1 ½ times more likely to have gallstones than if they did not have a first-degree relative with gallstones. Further support comes from twin studies that show that genetic factors are important in determining who develops gallstones. Among non-identical pair of twins (who share 50% of their genes with each other), both individuals in a pair have gallstones 8% of the time. Among identical pair of twins (who share 100% of their genes with each other), both individuals in a pair have gallstones 23% of the time.
There are several types of gallstones and each type has a different cause.
Cholesterol gallstones
Cholesterol gallstones are primarily of made up of cholesterol. They are the most common type of gallstone, comprising 80% of gallstones in individuals in Europe and the Americas. Cholesterol is one of the substances that liver cells secrete into bile. (Secretion of cholesterol into bile is an important mechanism by which the liver eliminates excess cholesterol from the body.)
In order for bile to carry cholesterol, the cholesterol must be dissolved in the bile. Cholesterol is a fat, however, and bile is an aqueous or watery solution; fats do not dissolve in watery solutions. In order to make the cholesterol dissolve in bile, the liver also secretes two detergent-bile acids and lecithin-into the bile. These detergents, just like dish-washing detergents, dissolve the fatty cholesterol so that it can be carried by bile through the ducts. If the liver secretes too much cholesterol for the amount of bile acids and lecithin it secretes, some of the cholesterol does not dissolve. Similarly, if the liver does not secrete enough bile acids and lecithin, some of the cholesterol also does not dissolve. In either case, the undissolved cholesterol sticks together and forms particles of cholesterol that grow in size and eventually form gallstones.
There are two other processes that promote the formation of cholesterol gallstones though neither process is able to form cholesterol gallstones by itself. The first is an abnormally rapid formation and growth of cholesterol particles into gallstones. Thus, with the same concentrations of cholesterol, bile acids and lecithin in their bile, patients with gallstones form particles of cholesterol more rapidly than individuals without gallstones. The second process that promotes the formation and growth of gallstones is reduced contraction and emptying of the gallbladder that allows bile to stay in the gallbladder longer than normal so that there is more time for cholesterol particles to form and grow.
Pigment gallstones
Pigment gallstones are the second most common type of gallstone. Although pigment gallstones comprise only 15% of gallstones in individuals from Europe and the Americas, they are more common than cholesterol gallstones in Southeast Asia. There are two types of pigment gallstones 1) black pigment gallstones, and 2) brown pigment gallstones.
Pigment is a waste product formed from hemoglobin, the oxygen-carrying chemical in red blood cells. The hemoglobin from old red blood cells that are being destroyed is changed into a chemical called bilirubin and released into the blood. Bilirubin is removed from the blood by the liver. The liver modifies the bilirubin and secretes the modified bilirubin into bile.
Black pigment gallstones: If there is too much bilirubin in bile, the bilirubin combines with other constituents in bile, for example, calcium, to form pigment (so-called because it is dark brown in color). Pigment dissolves poorly in bile and, like cholesterol, it sticks together and forms particles that grow in size and eventually form gallstones. The pigment gallstones that form in this manner are called black pigment gallstones because they are black and hard.
Brown pigment gallstones: If there is reduced contraction of the gallbladder or obstruction to the flow of bile through the ducts, bacteria may ascend from the duodenum into the bile ducts and gallbladder. The bacteria alter the bilirubin in the ducts and gallbladder, and the altered bilirubin then combines with calcium to form pigment. The pigment then combines with fats in bile (cholesterol and fatty acids from lecithin) to form particles that grow into gallstones. This type of gallstone is called a brown pigment gallstone because it is more brown than black. It also is softer than black pigment gallstones.
Other types of gallstones. Other types of gallstones are rare. Perhaps the most interesting type is the gallstone that forms in patients taking the antibiotic, ceftriaxone (Rocephin). Ceftriaxone is unusual in that it is eliminated from the body in bile in high concentrations. It combines with calcium in bile and becomes insoluble. Like cholesterol and pigment, the insoluble ceftriaxone and calcium form particles that grow into gallstones. Fortunately, most of these gallstones disappear once the antibiotic is discontinued; however, they still may cause problems until they disappear. Another rare type of gallstone is formed from calcium carbonate.