Pseudocalculus Defect

1. Pathogenesis:

• Pseudocalculus defects result from transient spasm of the sphincter of Oddi, which can be caused by the following:
   
• Common biliary duct exploration and surgical manipulation.
   
• Forceful contrast medium injection.
   
• Anesthetic and analgesic agents (fentanyl citrate, morphine SO4).
   
• The treatment is to relax the sphincter of Oddi. The sphincter may relax with time or glucagon may be administered.
   

2. Radiographic findings:

• Meniscus filling defect in distal end of common bile duct and no flow of contrast agent into the duodenum.
   
• Cannot be distinguished from an impacted stone until sphincter of Oddi relaxes, causing filling defect to disappear and permitting contrast agent to flow into the doudenum.
   
• Figures: pseudocalculus defect during T-tube cholangiogram (A&B). Meniscus seen at distal end of common bile duct simulating an impacted stone obstructing flow of contrast agent into the duodenum. (C) Later, defect is gone and contrast agent flows into the duodenum.
   

                     
         A                                                          B                                                           C