A gallstone is a crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

line concretion

Enterolith

An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting...

 formed within the gallbladder

Gallbladder

In vertebrates the gallbladder is a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. In humans the loss of the gallbladder is usually easily tolerated....

 by accretion of bile

Bile

Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...

 components. These calculi

Calculus (medicine)

A calculus is a stone that forms in an organ or duct of the body. Formation of calculi is known as lithiasis...

 are formed in the gallbladder, but may pass distally into other parts of the biliary tract such as the cystic duct

Cystic duct

The cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length...

, common bile duct

Common bile duct

The common bile duct is a tube-like anatomic structure in the human gastrointestinal tract. It is formed by the union of the common hepatic duct and the cystic duct . It is later joined by the pancreatic duct to form the ampulla of Vater...

, pancreatic duct

Pancreatic duct

The pancreatic duct, or duct of Wirsung , is a duct joining the pancreas to the common bile duct to supply pancreatic juices which aid in digestion provided by the "exocrine pancreas"...

, or the ampulla of Vater.

Presence of gallstones in the gallbladder may lead to acute cholecystitis

Cholecystitis

-Signs and symptoms:Cholecystitis usually presents as a pain in the right upper quadrant. This is known as biliary colic. This is initially intermittent, but later usually presents as a constant, severe pain. During the initial stages, the pain may be felt in an area totally separate from the site...

, an inflammatory

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 condition characterized by retention of bile in the gallbladder

Cholestasis

In medicine, cholestasis is a condition where bile cannot flow from the liver to the duodenum. The two basic distinctions are an obstructive type of cholestasis where there is a mechanical blockage in the duct system such as can occur from a gallstone or malignancy and metabolic types of...

 and often secondary infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 by intestinal microorganisms

Gut flora

Gut flora consists of microorganisms that live in the digestive tracts of animals and is the largest reservoir of human flora. In this context, gut is synonymous with intestinal, and flora with microbiota and microflora....

, predominantly Escherichia coli

Escherichia coli

Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...

and Bacteroides

Bacteroides

Bacteroides is a genus of Gram-negative, bacillus bacteria. Bacteroides species are non-endospore-forming, anaerobes, and may be either motile or non-motile, depending on the species. The DNA base composition is 40-48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids...

species.