16 Questions
Why is it important to fast the patient?
To minimize artefacts during the examination
What is the recommended probe frequency for gallbladder examination?
3-MHz
What is the primary tool for assessing the structure of the biliary tree?
Ultrasound
What is Caroli's disease?
A congenital disorder
What is the common anatomic variation in the biliary tree?
Extrahepatic junction of the right and left hepatic ducts
What is the recommended patient position for imaging the common bile duct?
Supine
What is the name of the duct that joins the CBD?
Pancreatic duct
What is the site where the CBD enters the duodenum?
Ampulla of Vater
What can be used to move anatomy out from beneath the ribs?
Inspiration and expiration
What is the purpose of assessing the pancreas during gallbladder examination?
To visualize the common bile duct
What is the purpose of cannulating the CBD during cholecystectomy surgery?
To image for duct calculi
What can cause obstruction in the bile duct?
All of the above
What is the term for the inflammation of the bile ducts?
Cholangitis
Why is it important to measure the diameter of the extrahepatic bile duct?
To diagnose obstruction
What is the term for the presence of a stone in the CBD?
Choledocholithiasis
What is the function of the Sphincter of Oddi?
To regulate the flow of bile into the duodenum
Study Notes
Anatomy of the Biliary Tree
- The biliary tree originates from canaliculi at hepatocytes, merging to form the right and left hepatic ducts, which join at porta hepatis to form the Common Hepatic Duct (CHD).
- The Common Bile Duct (CBD) is formed by the junction of the cystic duct with the CHD.
- The CBD traverses through the head of the pancreas, entering the duodenum at the Ampulla of Vater through the Sphincter of Oddi.
- The pancreatic duct joins the CBD before it drains into the duodenum.
Variations in Anatomy
- A common anatomic variation is to have an extrahepatic junction of the right/left hepatic ducts, occurring in 20% of people.
- Another variation is for the right hepatic duct to join the cystic duct rather than merge with the left hepatic duct.
Ultrasound and Scan Protocol
- Ultrasound is the primary tool for assessing the structure of the biliary tree.
- Scan protocol involves using a curvi-linear probe, with adjustments for patient habitus, and good colour/power/Doppler capabilities.
- Patient preparation involves fasting, and the patient may need to be positioned supine, erect, or left decubitus during the scan.
Limitations and Applications
- Limitations of ultrasound include non-fasted patients and large habitus patients.
- Ultrasound is useful for assessing obstruction, cholangitis, choledochal cysts, cholangioma, and guiding injections, aspirations, or biopsies.
Pathology
- Obstruction can be due to intraductal (calculus, sludge, tumor) or extraductal (tumor extrinsic compression, tumor invasion, collection) causes.
- Cholangitis and Caroli's disease are other pathologies that can be assessed with ultrasound.
Learn about the anatomy of the biliary tree, from the canaliculi to the ampulla of Vater. Understand how the ducts merge and form the common bile duct.
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