Ultrasound Techniques Bile duct measurements

Techniques Bile duct measurements

The main, right and left hepatic ducts tend to lie anterior to the portal vein branches; however as the

biliary tree spreads out, the position of the duct relative to the portal branches is highly variable.

Don’t assume that a channel anterior to the PV branch is always a biliary duct—if in doubt, use

colour Doppler to distinguish the bile duct from the portal vein or hepatic artery.

The proximal bile duct is best seen either with the patient supine, using an intercostal approach

from the right, or turning the patient oblique, right side raised. This projects the duct over

the portal vein, which is used as an anatomic marker. Scanning the distal duct usually requires more

effort. Right oblique or decubitus positions are useful. Gentle pressure to ease the duodenal gas

away from the duct can also be successful. Sometimes, filling the stomach with water (which

also helps to display the pancreas) and allowing it to trickle through the duodenum does the trick.

Try also identifying the duct in the pancreatic head (Fig. 2.37) and then tracing it retrogradely

towards the liver. Asking the patient to take deep breaths is occasionally successful, but may make

matters worse by filling the stomach with air. It is definitely worth persevering with your technique,

particularly in jaundiced patients.

 

The common bile duct (arrow) seen on the head of pancreas on transverse section.

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