Flashcards in Biliary Tree and Gallstones Deck (32):
Describe the biliary tree.
Biliary canaliculi to
interlobular bile ducts to
septal bile ducts to
intrahepatic ducts to
right and left hepatic ducts to
common hepatic duct to
common bile duct
Where does the bile duct pass?
Passes behind the duodenum, through the head of the pancreas to join the main pancreatic duct, becoming the bile duct.
This then enters the duodenum at the major/minor duodenal papilla
Where is the gallbladder located?
In the gallbladder fossa on the inferior surface of the right lobe of the liver
What is the epithelial lining and function of the gallbladder?
- concentrates bile by absorbing water and electrolytes
What is bile composed of?
Describe the bile acid synthesis.
Derived from cholesterol in the hepatocyte. Cholic acid is the primary bile acid
Describe bile salt synthesis.
Cholic acid is conjugated to bile salts by the addition of an amino acid group (taurine or glycine) before active export. These are primary bile salts.
What forms secondary bile salts.
The action of intestinal bacteria (de-hydroxylation) of primary bile salts
What causes gallbladder contraction?
CCK release into the duodenum
- causes by detection of luminal fat
- sphincter of Oddi relaxation
What causes gallbladder relaxation?
What do the following and and prefixes mean?
Chol = bile
Lith = stone
Docho = duct
Ang = vessel
itis = inflammation
iasis = process
What is the function of bile salts?
Promote emulsification and formation of micelles to help fat absorption
- fat soluble vitamins are absorbed
- facilitates cholesterol excretion by solubilising it in bile
Influences the intestinal metabolic pathways
What is the entero-hepatic circulation?
95% of bile salts are reabsorbed from the gut (6-8 times a day)
- they are reabsorbed by the terminal ilium by active transport into the portal vein
How do bile salts travel in the blood?
Bound to albumin because it's hydrophobic
What are the risk factors for gallstones?
The six F's
- family history
Low fibre diet
Inflammatory bowel disease
Name the three types of gallstones.
Bile pigment stones
Describe cholesterol stones.
Oval and large (up to 3cm)
Describe bile pigment stones.
Hard and irregular
Can be associated with chronic heamolysis (sick cell)
Describe mixed stones.
The most common (80%)
Multiple and multi-faceted
Has a laminated structure with layers of bile pigment, cholesterol and calcium salts
In gallstone pathogenesis there are three main events (that often occur toegther). What are they?
Increased bilirubin secretion
Describe the process of cholesterol supersaturation.
Cholesterol is normally solubilised in bile, but very high levels cause supersaturation.
This can be due to increased oestrogen or decreased bile salt levels.
When does biliary stasis occur?
Occurs during periods of fasting, starvation or prolonged enteral feeding
Describe what happens in increased bilirubin secretion.
Pigmented stones can develop in increased heamolysis or a failure in hepatic conjugation
What complications can gallstones in the gallbladder cause?
- can cause jaundice and abnormal LFTs
- stone impacted in gallbladder
- pain when eating
What complications can gallstones in the common bile duct cause?
What complications can gallstones in the small intestine cause?
What are some of the casues of obstructive jaundice?
Benign bile duct stricture
What are the signs and symptoms of obstructive jaundice?
Pale stools and dark urine
S/S of chronic liver disease
Where do gallstones commonly impact in the bile duct?
The ampulla of Vater
How do you diagnose a gallstone in the bile duct (choledocholithiasis)?
Ultrasound with or without EUS and MRCP to confirm
Treatment of gallstones in the bile duct?
- antibiotics if cholangitis
- ECRP to attempt stone removal (incision in the sphincter of Oddi to increase the diameter)
- cholecystectomy to prevent recurrence