One fifth of adults in Western countries have gall stones, but more than 80% are asymptomatic. There are 3 types of gall stones: cholesterol, black pigment, and brown pigment. In Western countries, 80% are cholesterol stones, while pigment stones are the major type in non-Western countries. Approximately 10% of all females and 5% of all males have gall stones. Of these patients with gall stones, 1-2% will become symptomatic each year.
With symptomatic gall stones, the risk of complications from the gall stones is greater than the risks of surgery, which are future attacks, cholangitis, pancreatitis, perforated gall bladder and such. The surgery is usually performed laparoscopically or open. Non-surgical management includes a low-fat diet, medications to try to dissolved the stones, and a cholecystostomy tube.
Cholesterol stones are predominantly composed of colesterol (>50%). European, North and South American, and Native Americans populations are at increased risk, and there is also a female preponderance that is likely related to estrogen and pregnancy. Other risk factors include advancing age, obesity, rapid weight loss, diabetes, gall bladder stasis, ileal disease, bypass or resection, and family history.
Estrogen increases cholesterol uptake and synthesis by the liver. Bile cholesterol secretion is increased with obesity and rapid weight loss. Gallbladder emptying is reduced with prolonged fasting, pregnancy, and rapid weight loss. Ileal disease or surgery affects the enterohepatic circulation of bile salts.
Cholesterol stones form in three stages: First, there is cholesterol supersaturation, which depends on the concentrations of cholesterol, bile salts and lecithin. This supersaturation originates in the liver, not from bile undergoing concentration in the gall bladder. Next, nucleation occurs, which is the aggregation of cholesterol crystals around particles such as bacteria, mucus, parasitic ova, or calcium salts. Last, there is crystal growth, which is affected by gall bladder motility and inflammation.
Often, there are multiple cholesterol stones. Pure stones are pale yellow, round to ovoid, and hard, with a crystalline appearance on sectioning. With increasing amounts of calcium salts and bilirubin, they may be layered and gray to black. 10-20% of these stones are radio-opaque.
Black pigment stones
Black pigment stones are composed of polymerized bilirubin. These stones are associated with chronic hemolysis and cirrhosis, especially alocholic cirrhosis. In chronic hemolysis, there is supersaturation of the bile with unconjugated bilirubin. In cirrhosis, bile composition is altered, and there may also be an element of hemolysis.
These stones are hard, usually radio-opaque (60%), form in the gall bladder, and may pass into the bile duct.
Brown pigment stones
Brown pigment stones are composed of calcium bilirubinate. They are associated with bile stasis (due to chronic partial biliary obstruction) and infection. Deconjugation of bilirubin by bacteria results in precipitation of insoluble unconjugated bilirubin. In Asia, there is an association with parasitic infections.
These stones are small, soft, friable, radiolucent and form in bile ducts.