Gallstone Classification in Western Countries.

In order to compare gallstone disease data from India and Asian countries with Western countries, it is fundamental to follow a common gallstone classification. Gallstone disease has afflicted humans since the time of Egyptian kings, and gallstones have been found during autopsies on mummies. Gallstone prevalence in adult population ranges from 10 to 15 %. Gallstones in Western countries are distinguished into the following classes: cholesterol gallstones that contain more than 50 % of cholesterol (nearly 75 % of gallstones) and pigment gallstones that contain less than 30 % of cholesterol by weight, which can be subdivided into black pigment gallstones and brown pigment gallstones. It has been shown that ultrastructural analysis with scanning electron microscopy is useful in the classification and study of pigment gallstones. Moreover, x-ray diffractometry analysis and infrared spectroscopy of gallstones are of fundamental importance for an accurate stone analysis. An accurate study of gallstones is useful to understand gallstone pathogenesis. In fact, bacteria are not important in cholesterol gallstone nucleation and growth, but they are important in brown pigment gallstone formation. On the contrary, calcium bilirubinate is fundamental in black pigment gallstone formation and probably also plays an important role in cholesterol gallstone nucleation and growth.