Gallbladder/bile duct pathology

Gallbladder/bile duct pathology

Bile stones

When the gallbladder contains bile stones, they can be imaged effectively using ultrasound. Bile stones are echogenic and opaque, causing “acoustic shadowing” immediately behind the stone (fig. 30).

In order to evaluate bile stone mobility, you can ask the patient to lie on his or her left side or stand if possible. The bile stones will move to the bottom with gravity. An immobile echogenic nodular lesion in close correlation with the gallbladder wall without acoustic shadowing is termed a gallbladder polyp, frequently consisting of cholesterol (fig. 31). The polyps will not move with gravity.

Cholecystitis

If there is a bile stone in the gallbladder neck that does not move with gravity, this is termed a “lodged stone”. It causes biliary outflow obstruction, putting pressure on the gallbladder. The gallbladder base will no longer be compressible and the patient will also indicate pain when you press on the gallbladder: this is a “hydropic gallbladder” or “Murphy’s sign".  When the bile stone has been lodged chronically with associated bile stone colic, the gallbladder wall will thicken and have a layered aspect: the wall has become edematous (fig. 32/33).

Dilated bile ducts

The choledochal duct can be evaluated by localizing the portal vein in the liver hilum; the choledochal duct is ventral of the portal vein. The choledochal duct usually has a diameter < 7 mm. A stone in the choledochal duct may cause obstruction and dilatation.

The intrahepatic bile ducts are too small for ultrasound evaluation. In the event of bile duct obstruction, the intrahepatic bile ducts will become visible (fig. 35a/b). This is termed the tram track sign (fig. 35a).