The term cholelithiasis, is a medical term that refers to the presence of gallstones within the gallbladder

Types of Gallstones

Biliary sludge is often a precursor of gallstones.  Sludge develops during gallbladder stasis and consists of calcium bilirubinate, cholesterol crystals and mucin.  Most sludge resolves,  however it can evolve into gallstones.  Gallstones usually grow at about 1-2mm per year, taking 5-20 years to become large enough to cause a problem. 

Cholesterol Gallstones

These are the most common type of gallstone accounting for 80% of gallstones seen in the Western world. They are usually yellow-green in colour being composed principally of cholesterol. As they don’t contain calcium they are not usually visible by x-ray.

Pigment Gallstones

They are less common and being composed of bilirubin they are darker in colour.  They can be divided into black pigment stones that are small, and hard and usually the result of chronic breakdown of red cells (hemolysis), or brown pigment stones that are soft and greasy.  These are usually the result of chronic biliary infection, inflammation or parasitic infection (liver flukes).   

Causes of Gallstones 

In most people there is no known cause for developing gallstones.  

Gallstones may develop when

  • There is too much cholesterol in the bile. Cholesterol is normally dissolved in bile. If the liver excretes too much cholesterol than the bile can dissolve, the excess cholesterol may form crystals that eventually form stones.
  • There is too much bilirubin. Bilirubin is one of the end products of red blood cell break down. There are a number of conditions that increase the production of bilirubin including certain blood conditions, liver disease or infections in the bile ducts. The excess bilirubin can crystalise to form pigment stones.
  • The gallbladder doesn’t completely empty. Incomplete emptying of the gallbladder causes the bile within it to become concentrated, that allows for crystalisation and subsequent stone formation.
  • Chronic inflammation, infection or parasitic infestation (liver fluke) of the bile ducts.

Risk Factors of Gallstones

There are a number of risk factors attributed to the development of gallstones

This includes female, pregnancy, 40 years of age or older, overweight or obesity, diabetes mellitus, family history of gallstones, losing weight rapidly, eating high fat diet, eating a low-fibre diet, taking estrogen-containing medications (oral contraceptive pill or hormone replacement therapy), taking medicine to lower cholesterol (may increase amount of cholesterol excreted into bile), liver disease, conditions increasing red blood cell breakdown (Hemolysis).