Ultrasound of the abdomen shows a hyperechoic structure within a dilated common bile duct casting an acoustic shadow, with upstream biliary dilatation. The 'double duct sign' on MRCP (simultaneous dilatation of both the common bile duct and the main pancreatic duct) is most classically associated with:
- A Carcinoma of the head of pancreas ✓
- B Choledocholithiasis causing biliary obstruction
- C Mirizzi syndrome
- D Primary sclerosing cholangitis
Correct answer: A. Carcinoma of the head of pancreas
Explanation
The 'double duct sign' — simultaneous dilatation of the common bile duct and the main pancreatic duct — is the hallmark of obstructing carcinoma of the pancreatic head at the level of the ampulla of Vater, which compresses both ducts. Choledocholithiasis obstructs the CBD but not the pancreatic duct. Mirizzi syndrome is extrinsic compression of the CHD by a gallbladder stone. PSC causes stricturing and beading of bile ducts without pancreatic duct dilation.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.