Computed tomography in obstructive jaundice. Part I: The level of obstruction.

Computed tomographic (CT) scans of 67 cases of obstructive jaundice were analyzed to determine the value of CT in detecting the level of obstruction. The cases were divided into four groups by anatomical segments, according to the number of visualized hypodense ringlike structures produced by the dilated bile duct, as seen in axial sections made 1 cm apart. Gallbladder size, dilatation of intrahepatic biliary radicals and the pancreatic duct, visualization of tumor masses, and condition of the bile duct below the obstruction were other variables used to determine the level of obstruction. The overall accuracy of CT in determining the exact level has been 97%. The most reliable indicator is the number of rings, which has excellent correlation with the results of direct cholangiography. The diagnostic value of all other variables is limited to specific cases.