Cystic duct variant

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Shweta Bhatt, MD and Vikram S Dogra, MD
Instructor (SB) and Professor of Radiology (VSD)
University of Rochester, NY, USA

Figure Legends : 


Figure 1. CT cholangiogram coronal reconstructed image shows medial insertion of the cystic duct into the extrahepatic duct.


Figure 2. 3-D image of the CT cholangiogram showing the same variant. 

Case Description

Clinical History: 

41-yr-old female being evaluated as a liver donor. 



Cystic duct variant with medial insertion into the extrahepatic duct.



 The normal cystic duct is usually 2–4 cm long and 1-5 mm wide with a spiral appearance secondary to concentric folds known as the spiral valves of Heister. Congenital anatomic variants of the cystic duct are commonly seen, occurring in about 18%–23% of cases. The cystic duct inserts into the middle one-third of the extrahepatic bile duct in 75% of cases and into the distal one-third in 10%. It most commonly insert from a right lateral position but may have an anterior or posterior spiral insertion, low lateral insertion with a common sheath enclosing the cystic duct and common bile duct, proximal insertion, or low medial insertion at or near the ampulla of Vater.

The level of cystic duct insertion varies, with an abnormal proximal or distal union accounting for 55% of biliary ductal anatomic variants. The cystic duct may join the right hepatic duct, the left hepatic duct (rarely), or the common hepatic duct high in the porta hepatis . It empties into the proximal common hepatic duct or into the right hepatic duct on 0.3% of cholangiograms . The insertion may be low in the intrapancreatic or intraduodenal portion or at the level of the ampulla of Vater. Rarely, the cystic duct inserts directly into the duodenum.

CT cholangiography was first described in 1982 by Greenberg et al who succeeded in opacifying the distal common bile duct using an oral hepatotropic contrast agent. With the advent of helical CT, several investigators experimented with the innovative approach of creating 3D CT cholangiograms. However, the use of IV cholangiographic agents is limited because of reactions to iodipamide meglumine and its derivatives. CT cholangiography is now performed with an oral contrast agent using iopanoic acid. Opacification of the biliary anatomy is subject to many factors, thus technically limiting the reliability of CT cholangiography as an imaging alternative particularly in the presence of biliary disease.


References / Suggested Reading: 

  1. Turner M, Fulcher A.The Cystic Duct: Normal Anatomy and Disease Processes. Radiographics. 2001;21:3-22

  2. Caoli E, et al. Helical CT Cholangiography with Three-Dimensional Volume Rendering Using an Oral Biliary Contrast Agent. AJR 2000. 174:487-492 


Cystic duct variant, Shweta Bhatt, MD and Vikram S Dogra, MD, Imaging Science Today, 2009, 128.


drrajeshsharma's picture
Joined: 08/10/2007

This variant has been nicely demonstrated by the CT images and a very good discussion has been included in this case report. MR imaging & MRCP are the preferred non invasive imaging modalites at many centres.

Dr.Rajesh Sharma MD, DMRD, Department of Radiodiagnosis, Government Medical College, Jammu (J&K) India