Gallstones are quite prevalent in most western countries. Gallstones are formed by concretion or accretion of normal or abnormal bile constitutes. They are divided in 4 types: Cholesterol rich stone results from failure of the liver to provide enough bile salts and lecithin, from increased hepatic syntheses of cholesterol, or from both. Super saturation of bile with cholesterol is the end result. Stone-formation also requires an initial nucleation step, in which a nidus (for example precipitated cholesterol, mucous, calcium salts, cell debris) must be present.
Once formed the stone enlarges by continuous precipitation of cholesterol. Gallbladder hypomotility as seen after surgery, burns, pregnancy and use of oral contraceptives favors gallstone growth. There are two types of cholesterol stones 1) mixed stones—comprised about 75% of gallstones, they usually are multiple, multifaceted, and laminated, having a crystalline appearance on cut surface and measure up to 3cm in diameter. Varying combinations of cholesterol (at least 60% of stone content), calcium carbonate, and calcium bilirubinate comprise the stones.
The specific composition determines the color which ranges from yellow to brown to green. 2) Pure cholesterol stones (at least 90% cholesterol content) comprise about 10% of all stones. They occur singly and are oval crystalline, about 1 to 6 cm in diameter and are white to pale yellow. Pigment stones comprise about 10 to 20% of all stones, they are usually multiples, a few millimeters in diameters, and contain a variety of insoluble calcium salts, including calcium bilirubinate and cholesterol (usually less than 20% by weight). There are two types, black and brown. Combined stones comprise about 5% of gallstones.
They may have a cholesterol or pigment nucleus with a mixed stone shell or vice versa. They usually are solitary barrel shaped and large might be filling the entire gallbladder. Calcium carbonate stones are rare, they are grayish white and amorphous. (Vinay Kumar, Ramzi S. Cotran, Stanley L. Robbins, 2004). Etiology: The mnemonic known as five Fs (fair, fat, fertile, female, forty) is used to describe the typical patient with an increased risk for gallstones, but obviously this is an oversimplification. It appears that two risk factors obesity and high chloric diet increase the hepatic secretion of cholesterol.
A diet rich in unrefined sugars may decrease the bile acid pool precipitating gallstones. Conditions associated with an increased risk of cholesterol gallstones are old age, oral contraceptive use, intestinal resection or bypass surgery and Crohn’s disease. Pregnancy, multiparity, diabetes mellitus and hyperthyroidism also contribute in its causation. Old age, chronic hemolytic anemia, cirrhosis, billiary tract infections are the predisposing risk factors for the pigment gallstones (Eve A. Kerr, Steven M. Asch, Eric G. Hamilton, Elizabeth A. Mcglynn, 2000).