Double-barrel shotgun sign

Excerpt

Dilated common bile duct (CBD) of the same size as the portal vein at the porta was classically described as the “shotgun sign” (Figure 1) [1]. Dilated intrahepatic biliary radicles within the liver parenchyma adjacent to the portal vein branches also gives the “double barrel shotgun” appearance (Figure 2); it is also known as the “parallel channel sign” or “too many tubes sign” [2]. The double-barrel sign is a highly accurate sign for intrahepatic biliary duct dilatation [3]. The dilated biliary tree and portal vein branches resemble the barrels of the over-and-under designs of the modern double-barrel shotgun (Figure 3)[3]. Enlarged hepatic arteries within the substance of the liver may give false-positive “double barrel shotgun” appearance on gray scale ultrasound, but color Doppler easily differentiates the biliary tree and the hepatic arteries [3, 4]. Subcostal oblique view of the porta hepatis is quite sensitive for detection of dilatation of the intrahepatic bile ducts [4]. Double-barrel sign on ultrasound should prompts a detailed evaluation for an obstructing lesion along the biliary tree.

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