Ultrasonography in the diagnosis of obstructive jaundice.

Forty-seven patients with cholestatic jaundice were evaluated for extrahepatic biliary obstruction by ultrasonic cholangiography and the results verified by contrast cholangiography, celiotomy, or autopsy. Sonograms were evaluated both with ("official" reading) and without ("blind" reading) clinical information. By showing dilated bile ducts, sonography correctly diagnosed extrahepatic obstruction in 26 of 30 patients on "official" reading and 23 of 30 on "blind" reading. In all 17 patients without extrahepatic obstruction, sonography revealed the absence of dilated bile ducts. Among patients with extrahepatic obstruction, those with larger bile ducts had higher bilirubin concentrations, longer duration of jaundice, and were more reliably detected by sonography. In these patients, 94% with total bilirubin concentration greater than 10 mg/dl were detected by sonography, while 47% with total bilirubin concentration less than 10 mg/dl were detected. Although we recognize the limited sensitivity of sonography in early extrahepatic obstruction, we find it to be a valuable screening test in cholestatic jaundice.