Gallstones chiefly form from constituents of the bile. (viz. cholesterol, bile pigments, and calcium salts). Generally along with other organic components.

Accordingly, it commonly contains cholesterol, bile pigment and calcium salts in different proportions.

They usually form in the gallbladder. but sometimes can form within extrahepatic biliary passages. and rarely in the large intrahepatic bile duct.


  1. The incidence of cholelithiasis significantly varies in diff. geographic areas, age, gender, diet, and various other risk factors.
  2. These factors can be summed up accordingly. in the old saying gallstones are common in 4F’s acronym for.—‘fat, female, fertile (multipara) and forty’.
  3. Geography.
    • It is further most prevalent in almost the entire Western world.
    • Generally, American Indians have the highest known prevalence. Black Africans and populations in the Eastern world are subsequently free of cholelithiasis.
  4. Genetic factors.
    • There is a surprisingly increased frequency in first-degree relatives of patients with cholelithiasis.
    • Patients have increased secretion of dietary cholesterol in bile. than in non-gallstone patients in spite of the high-cholesterol diet.
  5. Age.
    • There is a steady increase in the development of gallstones forthwith advancing age. This may be occasionally related to increased cholesterol content in the bile.
    • It increases above the age of 40. The presentation is usually in the 50s and 60s.
  6. Sex. Gallstones are twice more frequent in women than in men.
  7. Drugs. Women on oestrogen therapy or on birth control pills have a higher incidence.
  8. Obesity. Obesity is associated with increased cholesterol synthesis and it’s excretion. This results in a higher incidence of it in obese patients.
  9. Factors in pigment gallstones.
    • All of the above factors apply largely to cholesterol stones.
    • Pigment stones, whether pure or mixed type, are more frequently associated with haemolytic anaemias. This lead to increased content of unconjugated bilirubin in the bile.
    • Pigment stones are also more common in cirrhosis and hepatocellular disease.


    • Cholesterol is insoluble in water. It can solubilize by another lipid.
    • Normally, cholesterol and phospholipids (lecithin) secrete into bile as ‘bilayered vesicles’. But convert into ‘mixed micelles’ by the addition of bile acids.
    • If there is an excess of cholesterol as compared to the other two constituents. Then unstable cholesterol-rich vesicles remain behind that therefore aggregate. and form cholesterol crystals finally.
    • Formation of such lithogenic bile is explained by the following mechanisms:-
gallstones formation
  • Supersaturation of bile: Several etiologic factors listed above favor increased secretion of cholesterol. in the presence of normal bile acids and lecithin in the bile. as the major mechanism for the initiation of gallstone formation.
  • Cholesterol nucleation. Initiation of cholesterol stones occurs by nucleation of cholesterol monohydrate crystals.
  • Gallbladder hypomotility. The gallbladder is capable of emptying and clearing any sludge or debris normally. This might initiate stone formation.


As said earlier, gallstones contain cholesterol, bile pigment, and calcium carbonate. It can be either in pure form or in various combinations. Accordingly, they are of 3 major types—pure gallstones, mixed gallstones, and combined gallstones.

Pure gallstones of various types
Pure gallstones of various types
Mixed and combined gallstones
Mixed and combined gallstones


  • In about 50% of cases, gallstones cause no symptoms. They may be diagnosed by chance during investigations for some other condition (silent gallstones).
  • Symptomatic gallstone disease appears only when complications develop. These are the following:
Cholesterolosis of the gallbladder.
The lamina propria
of the mucosa shows foamy macrophages


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