Cholelithiasis – gallstones

Main types of gallstones

- cholesterol

- pigment (brown, black)

- composed of the following chemical constituents (in varying amounts):

-cholesterol, calcium bilirubin salts, calcium salts, bile salts, mucin glycoproteins

- <10% of cholesterol stones are pure (>90% cholesterol)

- 80% of stones in Western world are cholesterol stones

Risk Factors

Cholesterol stones

- older patients, overweight, parous female

- rapid weight loss

- certain ethnicities

- estrogenic effects (oral contraceptive pill, pregnancy)

Pigment stones

- elevated levels of unconjugated bilirubin

-chronic hemolysis

- ileal dysfunction

- cirrhosis

- bacterial contamination of biliary tree (often E. Coli) which release enzymes which hydrolyze and breakdown bilirubin

Causes of Gallstone Formation

Cholesterol stones

- cholesterol is normally soluble in bile by admixing with bile salts and lecithins

- if cholesterol concentrations exceed the solubilizing capacity of bile there is formation of solid cholesterol crystals
See Figure 19-47 (Robbins)

In summary, the main events that need to happen for the development of cholesterol stones:

-bile supersaturation

-crystal nucleation (initial formation of solid cholesterol crystals)

propagated by:

-gallbladder hypomobility

-mucus hypersecretion

-accumulation of calcium salts

with final formation of solid nidus (stone)
b) Pigment stones

-unconjugated bilirubin normally minor component of bile

-bacterial infection causes the release of enzymes which hydrolyze bilirubin

-chronic hemolysis leads to increased amounts of unconjugated bilirubin

→both scenarios overwhelm the normal solubility of bilirubin in the biliary tree leading to pigment supersaturation
4. Complications

-acute cholecystitis

-chronic cholecystitis

-choledocholithiasis

-gallstone ileus

-fistula

-perforation

-pancreatitis

-superimposed bacterial infection