Abstract

Background: The bile concretions formed inside the gallbladder are called gallstones. Gallstone disease is one of the major causes of morbidity, mortality, and economic burden throughout the world. Approximately 10% to 20% of the world population and 4.87% in Nepal are suffering from a gallstone.

Objective: The aim is to classify the gallstone samples based on morphological and cross-sectional evidences, and a comparative study of their chemical composition to understand the mechanism of formation.

Methods: Two types of gallstones were studied; combined cholesterol gallstone and black pigment gallstone. SEM, UV-Vis, and EDS analyzed the gallstones for morphological and elemental study.

Results: The UV-Vis spectrum showed characteristic peaks for cholesterol, calcium bilirubinate, and copper bilirubinate. SEM image of combined cholesterol gallstone reveals that cholesterol is the major phase in the shell, whereas bilirubin is the major phase in the core. EDS detection of C and O as the major elements confirmed cholesterol, whereas the detection of C, O, N, and Ca as the major elements confirmed bilirubin. In the shell of the black pigment gallstone, cholesterol, calcium carbonate, calcium phosphate, and bilirubinate were detected, whereas, in the core, bilirubinate of calcium and copper, cholesterol, protein, and calcium carbonate were detected.

Conclusion: Cholesterol and bilirubin are the major components of the gallstones. Metals like Al, Ca and Cu play a crucial role in the initial formation of the gallstones. The combined cholesterol gallstone has a yellow pigment center composed mainly of unconjugated bilirubin and an outer shell primarily composed of cholesterol and calcium carbonate. Precipitation of bilirubinate of calcium and copper is important during the formation of black PGS.

Graphical Abstract