On MRCP (magnetic resonance cholangiopancreatography), the 'double duct sign' refers to simultaneous dilatation of:

• A Common bile duct and pancreatic duct due to periampullary/pancreatic head pathology ✓
• B Both hepatic ducts (right and left) due to hilar cholangiocarcinoma
• C Cystic duct and gallbladder due to cystic duct obstruction
• D CBD and cystic duct due to Mirizzi syndrome

Explanation

The double duct sign on MRCP (or ERCP) refers to simultaneous dilatation of both the common bile duct (CBD) and the main pancreatic duct (of Wirsung), most commonly due to carcinoma of the head of the pancreas or periampullary carcinoma compressing/obstructing both ducts at or near the ampulla of Vater. This sign has high predictive value for malignancy in the pancreatic head/periampullary region and warrants urgent further investigation. Hilar cholangiocarcinoma (Klatskin tumor) causes intrahepatic biliary dilatation with a stricture at the bifurcation. Mirizzi syndrome involves external compression of CBD by a gallstone in the cystic duct.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.