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The gallbladder (or cholecyst) is a pear-shaped organ that stores bile (or "gall") until the body needs it for digestion. It is connected to the liver and the duodenum by the biliary tract.
Anatomy
Not all mammals have gallbladders. The rat and horse, for example, do not have a specialised organ for the storage of bile. The gallbladder is connected to the main bile duct through the gallbladder duct (cystic duct or, in Latin, ductus cysticus). The main biliary tract runs from the liver to the duodenum, and the cystic duct is effectively a "cul de sac", serving as entrance and exit to the gallbladder. The surface marking of the gallbladder is the intersection of the mid-clavicular line (MCL) and the transpyloric plane, or the tip of the ninth rib. The blood supply is by the cystic artery and vein, which run parallel to the cystic duct.
Microscopic anatomy
The gallbladder has an epithelial lining characterised by recesses (called Aschoff's recesses), which are pouches inside the lining. Under the epithelium there is a layer of connective tissue, followed by a muscular wall that contracts in response to cholecystokinin.
Function
The gallbladder stores bile, which is released when food containing fat enters the digestive tract, stimulating the secretion of cholecystokinin (CCK).
Role in disease
Cholestasis
Cholestasis is the blockage in the supply of bile into the digestive tract. It can be "intrahepatic" (the obstruction is in the liver) or "extrahepatic" (outside the liver). It can lead to jaundice, and is identified by the presence of elevated bilirubin level that is mainly conjugated.
Cholelithiasis
Cholecystectomy seen through a laparoscope
Up to 25% of all people have gallstones (cholelithiasis), composed of cholesterol, lecithin and bile acids. These can cause colicky shooting abdominal pain, usually in relation with the meal, as the gallbladder contracts and gallstones pass through the bile duct. Surgery (cholecystectomy, removal of the gallbladder) is the most common treatment for gallstones. It can be performed laparoscopically, and it is in fact one of the most common procedures done through the laparoscope.
People traditionally considered at an increased risk of cholelithiasis are people who are 5 F's:
Cholecystitis
Please refer to main article: Cholecystitis
Acute or chronic inflammation of the gall bladder causes abdominal pain. 90% of cases of acute cholecystitis are caused by the presence of gallstones.
Choledocholithiasis
When gallstones obstruct the common bile duct, the patient develops jaundice and liver cell damage. It is a medical emergency, requiring endoscopic or surgical treatment.
Gallstone ileus
A rare clinical entity is ileus (bowel obstruction) by a large gallstone, or gallstone ileus. This condition develops in patients with longstanding gallstone disease, in which the gallbladder forms a fistula with the digestive tract. Large stones pass into the bowel, and generally block the gut at the level of Treitz' ligament or the ileocecal valve, two narrow points in the digestive tract. Therapy is surgical.
Gallbladder cancer
Gallbladder cancer is a rare but serious form of cancer. On biopsy, it is usually an adenocarcinoma. It may show on X-ray as a "porcelain gallbladder". The prognosis is poor.
Courvoisier's law
Courvoisier's law states that "the gallbladder is more often enlarged in malignancy than in gall stone disease". Courvoisier's sign is an enlarged, non-tender gallbladder together with jaundice; it is a sign of pancreatic carcinoma, in which the bile duct is obstructed and bile accumulates in the gallbladder.
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