Missing duct sign

Excerpt

Missing duct sign is produced when an intrahepatic stone completely obstructs the orifice of a segmental or subsegmental bile duct on cholangiogram in recurrent pyogenic cholangitis [1] (Figs. 1, 2). In an opacified biliary tree, the stones appear as filling defects. When a segmental duct fails to completely opacify due to an obstructing calculus, it is difficult to detect the calculus. Normal ducts, especially the left ducts, are sometimes not opacified, mimicking an intraductal calculus. However, the use of Trendelenburg, prone or left lateral positions would help to fill the patent unopacified ducts in this setting. Other characteristic imaging features of recurrent pyogenic cholangitis on cholangiogram include disproportionate dilatation of the extrahepatic bile ducts with minimal to no dilatation of intrahepatic ducts, multifocal intrahepatic biliary strictures, decreased arborization, and peripheral tapering of the intrahepatic ducts [2]. Recurrent pyogenic cholangitis represents a syndrome characterized by repeated episodes of bacterial cholangitis and the formation of pigment stones in the intrahepatic bile ducts. The disease is mainly seen in the Asian population with equal distribution in men and women in the 3rd and 4th decades of life [3]. Although the etiology is unknown, the disease is known to be associated with parasites such as Ascaris lumbricoides and Clonorchis sinensis. Inflammation caused by parasitic infestation of the biliary tree, resulting in scarring, strictures, bile stasis, and formation of intrahepatic pigment stones is the postulated pathophysiology. Complications of the disease include cholangitic abscess, segmental atrophy, biliary cirrhosis, portal hypertension, and cholangiocarcinoma [4].

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