Pseudocalculus sign (common bile duct)

The pseudocalculus sign is a term coined to describe a mimic of a distally impacted common bile duct (CBD) stone on ERCPMRCP and the various forms of cholangiography, including T-tubeCT, intraoperative, and percutaneous 1.

It results from the forceful contraction of the choledochal sphincter (of Oddi) at the ampulla of Vater with pouting into the lower end of the CBD. This impression is superiorly rounded imitating the superior surface of a stone, potentially leading to the misdiagnosis of choledocholithiasis.

Findings that support diagnosis of pseudocalculus rather than true calculus:

  • the inferior margin of the pseudocalculus will never be seen as it is not a true filling defect; if an inferior margin is visualized then pseudocalculus has been excluded
  • the pseudocalculus usually resolves with application of IV/IM glucagon which relaxes the choledochal sphincter
  • pseudocalculus will not impede the passage of contrast medium/bile nor be associated with abdominal pain
  • pseudocalculus lacks any calcification

The sign was first reported in 1968 by the renowned GI radiologist Thomas C Beneventano (1932-1988) who spent his entire career at the Albert Einstein College of Medicine in New York City 2,3.

Share article

Article information

rID: 8061
Section: Signs
Tag: cases
Synonyms or Alternate Spellings:
  • Pseudocalculus sign (biliary)

Support Radiopaedia and see fewer ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.