Gallstones form in the gallbladder, usually secondary to precipitation of cholesterol out of solution.
Because bile is a super-saturated solution, keeping cholesterol in solution depends on a critical ratio of concentrations of cholesterol, lecithin and bile salts being maintained.
If this ratio is disturbed by the concentration of any one of these three components increasing or decreasing, the cholesterol precipitates as cholesterol crystals. Cholesterol crystals act as the nidus for the development of most gallstones in the gallbladder. Some people form numerous small stones, while others form a few larger stones and others form large solitaire stones.
Rarely gallstones form within the bile ducts – primary bile duct stones. However, most stones found in the bile ducts have migrated there from the gallbladder. Gallstones may be present without any symptoms, but once symptoms start, they usually recur at variable intervals.
The most common symptom of gallstones is gallstone colic, which typically presents as intermittent attacks of severe pain in the central upper abdomen, which radiates round to the tip of the right shoulder blade and is sometimes associated with nausea. The attacks usually last 20 to 120 minutes, unless aborted by injected medication. Gallstone colic is due to sustained contraction of the gallbladder to try to force an obstructing stone through the cystic duct, the duct that connects the gallbladder to the main bile duct. Spontaneous cessation of the colic occurs when the smooth muscle of the gallbladder fatigues and the stone then drops back into the gallbladder.
Acute cholecystitis – chemical inflammation with superadded bacterial infection within an obstructed gallbladder; this can progress to gangrene of the gallbladder wall, perforation and abscess formation
Bile duct obstruction with jaundice - due to passage of a stone via the cystic duct into the main bile duct
Cholangitis – infection of an obstructed biliary system, leading to Gram negative septicaemia – a VERY serious, life-threatening condition
Acute pancreatitis – another very serious and potentially life-threatening complication caused by passage of a stone via the cystic duct into the main bile duct and obstruction within the ampulla of Vater, with reflux of bile into the pancreatic duct and activation of pancreatic enzymes inside the pancreas
Bowel obstruction – caused by erosion of a large gallbladder stone through the walls of the adjacent walls of the gallbladder and duodenum and migration of the stone into the intestine.
Surgical removal of the gallbladder, cholecystectomy, is advised for patients with symptoms attributable to demonstrated gallstones.
For people found incidentally to have gallstones, cholecystectomy is not always necessary if there are no symptoms, However, if there are other factors (e.g.diabetes) that make the development of complications unusually risky – one has to balance the risks of developing complications against the risks of undergoing surgery.
Removal of the gallbladder usually results in no discernable physiological changes, other than termination of attacks of colic. A small proportion of people who undergo cholecystectomy, notice their bowel habit changes slightly with modestly increased stool frequency. A very rare side effect of cholecystectomy is chronic diarrhoea.
The primary risk of cholecystectomy is an inadvertent injury to the main bile duct.