Gallstones Characteristics & composition 

Gallstones could vary in size from as small as a grain of sand to as large as a golf ball. The gallbladder might contain a single large stone or many smaller ones. Pseudoliths, sometime referred to as sludge, are thick secretions that might be present within the gallbladder, either alone or in conjunction with fully formed gallstones. The clinical presentation is similar to that of cholelithiasis. The composition of gallstones is affected by age, diet & ethnicity. On the basis of their composition, gallstones could be divided into the following types -

Cholesterol stones

Cholesterol stones vary in color from light-yellow to dark-green or brown & are oval 2 to 3 centimeters in length, often having a tiny dark central spot. To be classified as such, they must be at least 80% cholesterol by weight .

Pigment stones

Pigment stones are small, dark stones made of bilirubin & calcium salts that are found in bile. They contain less than 20% of cholesterol .

Mixed stones

Mixed gallstones typically contain 20–80% cholesterol . Other common constituents are calcium carbonate, palmitate phosphate, bilirubin, & other bile pigments. Because of their calcium content, they are often radiographically visible.

• Gallbladder opened to show numerous small cholesterol gallstones]]

• µCT of a gallstone. Image acquisition done using 'CT Alpha' by 'Procon X-Ray GmbH', Garbsen, Germany. Visualization done with 'VG Studio Max 2.0' by 'Volume Graphics', Heidelberg, Germany