Cholescintigraphy in the diagnosis of intrahepatic cholestasis. How specific is it?

Previous results from tests on a limited number of patients suggested that the combination of relatively normal hepatocyte clearance, prolonged parenchymal transit time, and eventual passage of radiotracer into the intestine or gallbladder without evidence of biliary tract dilatation were relatively specific for intrahepatic cholestasis. We reevaluated the specificity of cholescintigraphy for the diagnosis of intrahepatic cholestasis in an unselected group of patients from a general hospital. Sixteen patients had the cholescintigraphic findings of intrahepatic cholestasis and an established diagnosis of biliary tract dilatation or nondilatation by ultrasound, ERCP, or intraoperative cholangiography. Using 6 mm as the upper limits of normal for the diameter of the common hepatic duct by ultrasonography resulted in a specificity of 63% (10 correct out of 16); using 6 mm plus 1 mm for for every decade over 60 years of age gave a specificity of 75% (12 correct out of 16); and using the more liberal criterion of 8 mm as the upper limits of normal increased the specificity to 81% (13 out of 16). The data suggest that cholescintigraphy alone is unreliable in differentiating intrahepatic cholestasis from extrahepatic obstruction, even when the obstruction is partial and radiotracer eventually passes through the extrahepatic biliary tract.