Why are common bile duct (CBD) stones frequently missed on ultrasonography?

Updated: Apr 01, 2019
  • Author: Douglas M Heuman, MD, FACP, FACG, AGAF; Chief Editor: BS Anand, MD  more...
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Answer

Common bile duct (CBD) stones are missed frequently on transabdominal ultrasonography (sensitivity, 15%-40%). The detection of CBD stones is impeded by the presence of gas in the duodenum, possible reflection and refraction of the sound beam by the curvature of the duct, and the location of the duct beyond the optimal focal point of the transducer.

On the other hand, dilatation of the CBD on ultrasonographic images is an indirect indicator of CBD obstruction. CBD dilatation is identified accurately, with up to 90% accuracy. However, this finding may be absent if the obstruction is of recent onset. The usefulness of ultrasonography findings as a predictor of CBD stones is at best 15%-20%.

See Imaging of Cholelithiasis for complete information on this topic.


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