Gallstones
Overview
Gallstones also termed as choleliths medically, are small hard deposits of bile. The gallstones start as small bile crystals, turning into gravel and eventually forming small stones or pebbles. The gallbladder can contain either a single stone or hold up to hundreds of small gallstones. The size of the gallstones also varies; it could be as small as a grain of sand or as large as a golf ball. The term cholelithiasis refers to having gallstones in the gallbladder, whereas gallstones present in the ducts is termed as choledolithiasis.
Fig.5 Gallstones in gallbladder and ducts. n.d. [online] Available at:<http://www.mayoclinic.com/health/medical/IM00545> [Accessed 12 May 2013]
Types of Gallstones
Cholesterol Stones: Composed of cholesterol, these are large, smooth, egg or barrel shaped stones; usually occurring as solitary stones. These are yellowish in colour, with a size of up to 4cm in diameter, filling the gallbladder and appear radiolucent.
Pigment Stones: These could be either black pigment stones composed mainly of bilirubin and few calcium salts or brown pigment stones composed mainly of calcium bilirubinate and other calcium salts. Size ranging from 0.5-1cm and are usually of uniform size and often friable.
Mixed Stones: Composed predominantly of cholesterol and mixed with bile pigments and calcium salts. Colour ranges from being nearly white to yellow and green to black. Occur as multiple stones with variations in size and majority being radiolucent (few stones could be radiopaque).
Calcium Stones: Composed of calcium carbonate, these occur very rarely due to excessive calcium secretion in bile. Calcium stones are greyish faceted stones and are radiopaque.
In the USA and Europe, around 80% are cholesterol or mixed stones, whereas in Asia, 80% stones are pigment stones.
Pigment Stones: These could be either black pigment stones composed mainly of bilirubin and few calcium salts or brown pigment stones composed mainly of calcium bilirubinate and other calcium salts. Size ranging from 0.5-1cm and are usually of uniform size and often friable.
Mixed Stones: Composed predominantly of cholesterol and mixed with bile pigments and calcium salts. Colour ranges from being nearly white to yellow and green to black. Occur as multiple stones with variations in size and majority being radiolucent (few stones could be radiopaque).
Calcium Stones: Composed of calcium carbonate, these occur very rarely due to excessive calcium secretion in bile. Calcium stones are greyish faceted stones and are radiopaque.
In the USA and Europe, around 80% are cholesterol or mixed stones, whereas in Asia, 80% stones are pigment stones.
Fig.6 Gallbladder having pigmented and mixes stones. n.d. [online] Available at: <http://gogethealthynow.com/gallstones-causes-and-treatments/> [Accessed 12 May 2013]