Biliary Tree & Disorders
- To begin, we draw the biliary tree and indicate key landmarks and associated disorders.
- Liver: bile is created in the liver and travels to the gallbladder for storage. After eating, neurohormonal regulation triggers release of the bile into the duodenum, where it aids in digestion.
- Gallbladder
- Here we find cholelithiasis (gallstones) and cholecystitis, which is inflammation of the gallbladder.
- Then, show the biliary tree as follows:
- The right and left hepatic ducts join to form the common hepatic duct.
- The cystic duct drains the gallbladder and joins the common hepatic duct to become the common bile duct; this empties to the small intestine.
- Clinical conditions, which we’ll discuss further in this tutorial:
- Infection of the biliary tree is called “cholangitis”
- Pain caused by stones lodging in the cystic duct is called “Biliary colic”
- When stones lodge in the common bile duct, they cause a condition called “choledocholithiasis”
Gallbladder disorders are often asymptomatic, and are discovered incidentally, however, they may cause the following symptoms: upper right quadrant pain, nausea, and vomiting*.
Cholelithiasis
- Cholelithiasis is the medical term for gallstones, aka, calculi, which are hardened digestive juices in the gallbladder.
- Stone formation is the result of gallbladder stasis and biliary precipitate.
- It is thought that biliary sludge is the precursor to gallstones; this consists of calcium bilirubinate, cholesterol microcrystals, mucin, and develops during stasis (i.e., pregnancy and total parental nutrition). This can clear up, or it can progress to gallstone formation.
There are two key types of gallstones, depending on their constitution:
- Cholesterol-based gallstones: excess cholesterol forms crystals and gets trapped in gallbladder “sludge;” excessive cholesterol can be the result of excessive secretion (as we see in obesity) or with decreased bile salts (as we see in cystic fibrosis).
- Cholesterol-based stones make up 80-90% of all gallstones.
- Key risk factors for their formation include: obesity, elevated estrogen (female sex, pregnancy, multiparity, etc.), some medications, rapid weight loss or gain, being 40+ years old, and having American Indian or Central or South American ancestry.
- Pigment, aka, bilirubin, gallstones are less common.
- Black pigment stones are small and hard; they comprise calcium bilirubinate and inorganic calcium salts.
They are associated with alcoholic liver disease and chronic hemolysis.
- Brown pigment stones are soft and greasy; they comprise bilirubinate and fatty acids.
They are associated with bacterial and parasitic infection and inflammation.
- Gallstones are extremely common, and nearly always asymptomatic (80% of cases).
Biliary colic: when cholelithiasis is symptomatic, we call it “biliary colic” – this is typically characterized by right upper quadrant pain that can radiate to other areas, with possible nausea and vomiting*.
- It is an intermittent experience that is caused by gallbladder contraction that pushes a stone into the opening of the cystic duct; when the gallbladder relaxes, the stone usually falls back into the gallbladder and the pain subsides. (“colic” refers to the intermittent nature)
- In general, biliary colic is triggered by fatty meals, and the pain begins within an hour of eating; be aware that this pattern can vary significantly.
- Diagnosis: We use ultrasound to visualize and diagnose gallstones.
- Treatment: can include stone dissolution with oral ursodeoxycholic acid or laparoscopic cholecystectomy.
Complications of gallstones include inflammation and infection, which we’ll learn about in a moment.
“Porcelain gallbladder”
- This is the result of calcification of the inner wall of the gallbladder; it can range from a single plaque to a total replacement of the gallbladder wall.
- We show that the white gallbladder that stands out in imaging.
- On gross inspection, the gallbladder is fragile, brittle, and takes on a light bluish hue.
- This condition is most common in women older than 60, and nearly always in association with gallstones.
Porcelain gallbladder is usually asymptomatic; if symptomatic, we remove the gallbladder*.
- Be aware that cholecystectomy has traditionally been recommended in all cases of porcelain gallbladder, regardless of symptom status, due to the proposed link to gallbladder cancer.
However, recent studies shed doubt on this relationship, and some health care providers prefer a “wait and see” approach with asymptomatic patients.
Next, we’ll learn two disorders that occur when gallstones become lodged in the biliary tree.
Acute cholecystitis
- Gallbladder inflammation due to gallstone obstruction.
In contrast to the intermittent pain of simple cholelithiasis, cholecystitis is characterized by constant pain with possible fever and tachycardia*.
- Positive Murphy’s sign: palpate under the ribs in the right upper quadrant region and ask the patient to inhale - if the patient experiences pain and abrupt inspiratory arrest, we have a positive sign.
Choledocholithiasis
- Gallstone obstruction of the common bile duct, which leads to increased biliary tree pressure.
- Obstructing stones can originate in the gallbladder or within the common bile duct itself.
- As a result of increased pressure, we see elevated liver enzymes and jaundice.
- complications include gallstone pancreatitis (when the stone blocks the ampulla of Vater) and cholangitis.
Acute cholangitis
- Infection of the biliary tree.
- This is most commonly due to Gram-negative bacteria that get trapped in the bile.
Patients present with Charcot’s triad – severe RUQ tenderness, fever, jaundice*; they are also likely to have abnormal lab results.
We discuss
primary sclerosing cholangitis, primary biliary cholangitis, and
cholangiocarcinoma, elsewhere.
- For references, please see full tutorial.