Gallstone (aka cholelith) is a calculus (stone) formed within the gallbladder (i.e. organ where bile produced by the liver, is stored and concentrated before it is released into the small intestine). Cholelithiasis (from Greek "chol" meaning "bile", "lith" meaning "stone", and "isis" meaning "process) is lithiasis (stone formation) in the gallbladder.

• Usually asymptomatic

• Gallstones are formed as a concentration of bile components, including:
  • Cholesterol, most commonly
  • Calcium
  • Bilirubin
  • Pigment
  • Mixed 
• It may pass distally into other parts of the biliary tract (e.g. cystic duct, common bile duct, pancreatic duct, or ampulla of Vater)

• Ursodeoxycholic acid, to dissolve cholesterol gallstones. However, this drug may be required for up to 2 years. Also, galllstones may recur once the drug is stopped
• ERCP (endoscopic retrograde cholangiopancreatography), followed by ERS (endoscopic retrograde sphincterotomy), to relieve obstruction of the common bile duct w/ gallstones
• [Extracorporeal shock wave] lithotripsy, a procedure to break up gallstones, using concentrating ultrasonic shock waves onto the stones to break them into tiny pieces. They are then passed safely in the feces. However, this is only suitable when Pt's have a small number of gallstones
• Cholecystectomy (i.e. gallbladder removal), which has a 99% chance of elimiting recurrence of cholelithiasis. It is only indicated in Pt's w/ Sx. The lack of a gallbladder may have no negative consequences in many Pt's, but in 13% can cause postcholecystectomy syndrome, causing GI distress and persistent pain in the upper R abdomen, as well as chronic diarrhea

• Cholecystitis, an inflammatory condition characterized by retention of bile in the gallbladder, and often secondary infection by intestinal microorganisms (usually E coli, Klebsiella, Enterobacter, and Bacteroides)
• Presence of gallstones in other parts of the biliary tract can cause obstruction of the bile ducts, which can cause life threatening conditions:
  • Ascending cholangitis
  • Pancreatitis
• Gallstone ileus, rarely, which is a smal bowel obstruction caused by impaction of a gallstone within the lumen of a small intestine. It is where severe inflammation causes erosion through the gallbladder into adherent bowel, into the gut lumen via cholecysto-enteric fistula. Large stones (>2.5cm) predispose to fistula formation by gradual erosion through the gallbladder fundus. Most commonly, obstruction occurs at the distal ileum (i.e. ileoceccal valve) but can occur at almost any other location in the GI tract

• Cholecystitis
• Ascending cholangitis
• Pancreatitis
• Gallstone ileus
• Biliary colic (TRANSIENT obstruction)
• Choledocholithiasis (do NOT confuse)