The anatomy of the cystic duct and its association with cholelithiasis: MR cholangiopancreatographic study

The aims of this article are to detail the anatomy of the cystic duct in patients with and without gallstones as it relates to maneuvering of the duct during endoscopic transpapillary gallbladder cannulation, and to elucidate its role in the dynamics of bile flow during gallbladder contraction. One hundred MRCPs were retrieved from the prospectively maintained radiology data system to assess the configuration of the cystic duct and its confluence vis-a-vis the main biliary duct. The configuration of the cystic duct was broadly classified into four types: Angular (44%), Linear (40%), Spiral (11%), and Complex (5%). The level of emergence of the cystic duct from the bile duct was proximal in 29%, middle in 49% and distal in 20%. Its direction from the bile duct was to the right and angled upward in 69%, right and angled downward in 15%, left and angled upward in 13%, and left and angled downward in 1%. Its orifice was on the lateral surface of the bile duct in 50%, posterior in 19%, anterior in 15% and medial in 14%. In two cases, the cystic duct opened directly into the duodenum. Tortuous cystic ducts and non-lateral unions with the bile duct were significantly more prevalent in gallstone cases than the non-gallstone group (p = 0.02). The present study details the spatial anatomy of the cystic duct vis a vis the main biliary duct. This has not been well investigated to date but has become increasingly relevant with the advent of recent gallbladder interventions.