Ch. 54 – Biliary System

1554 Section X Abdomen
Figure 54-7 Ultrasound of liver identifying mass at hepatic duct
bifurcation (long arrow), pressing on confl uence of right and
left hepatic ducts (short arrow).
fi nding that does not distinguish them from other infectious
or infl ammatory causes.
Studies
Plain Radiographs
Although frequently obtained during the initial evaluation
of abdominal pain, plain radiographs of the abdomen in
patients with complaints localized to the right upper
quadrant are rarely helpful. Only about 15% of gallstones
contain enough calcium to render them radiopaque and
therefore visible on plain abdominal fi lms. Plain fi lms are
important to exclude other potential diagnoses, such as
perforated ulcer with free intraperitoneal air, bowel
obstruction with dilated loops of bowel, or right lower
lobe pneumonia on chest x-ray, that may mimic biliary
tract disease.
Ultrasonography
Ultrasound of the abdomen is an extremely useful and
accurate method for identifying gallstones and pathologic
changes in the gallbladder consistent with acute cholecystitis.
Abdominal ultrasound, if performed by an experienced
operator, should be part of the routine evaluation
of patients suspected of having gallstone disease, given
the high specifi city (>98%) and sensitivity (>95%) of this
test for the diagnosis of cholelithiasis 1 (Table 54-1). In
addition to identifying gallstones, ultrasound can also
detail signs of cholecystitis such as thickening of the
gallbladder wall, pericholecystic fl uid, and impacted
stone in the neck of the gallbladder. It is often the initial
Figure 54-8 CT cholangiogram shows enhanced imaging of the
biliary system comparable to MRC. Intrahepatic and extrahepatic
biliary ducts are clearly seen in this patient for evaluation for
living donor right hepatectomy.
screening test for patients with suspected extrahepatic
biliary obstruction (Fig. 54-7). Dilation of the extrahepatic
(>10 mm) or intrahepatic (>4 mm) bile ducts suggests
biliary obstruction. Intraoperative ultrasound is now used
frequently to further evaluate intrahepatic lesions, assess
resectability, and determine involvement of vascular
structures. 2
Oral Cholecystography
Once considered the diagnostic test of choice for gallstones,
oral cholecystography has been replaced by ultrasonography.
It identifi es fi lling defects in a visualized,
opacifi ed gallbladder after oral administration of a radiopaque
compound that passes into the gallbladder. Oral
cholecystography is of no value in patients with vomiting,
biliary obstruction, jaundice, or hepatic failure.
Computed Tomography
Although abdominal CT scanning is probably the most
informative single radiographic tool for examining intraabdominal
pathology, its overall value for the diagnosis
of biliary tract disease pales in comparison to ultrasonography.
The disadvantage is largely because gallstones and
bile appear nearly isodense on CT; that is, it is diffi cult
to distinguish gallstones from bile, unless the stones are
heavily calcifi ed. CT identifi es gallstones within the biliary
tree and gallbladder with a sensitivity of only about 55%
to 65%. Conversely, CT is more accurate at identifying
the site and cause of extrahepatic biliary obstruction.
Abdominal CT is a powerful tool for evaluating biliary
tract disease when the differential diagnosis includes a
question of hepatobiliary or pancreatic neoplasm, liver
abscess, or hepatic parenchymal disease (e.g., biliary cirrhosis,
organ atrophy). Use of CT cholangiogram provides
improved defi nition of the biliary tract comparable
to magnetic resonance cholangiography (MRC; Fig. 54-8).
Angiograms have now essentially been replaced by triplephase
liver CT angiogram.