Cystic duct is one of the bile ducts, which convey bile to the duodenum. It is about 1.5 inches long and connects the neck of the gallbladder to the common hepatic duct to form the common bile duct. Commonly, it is somewhat “S” shaped and descends for a variable distance in the right free margin of the lesser omentum.
The concentrated bile, which is stored in the gallbladder, passes through the cystic duct to reach the common bile duct and eventually to the duodenum. The cystic duct has an important anatomical feature. The mucous membrane of this duct is raised to form a spiral fold that is continuous with a similar fold in the neck of the gallbladder. This fold is commonly known as the “spiral valve” and its function is to keep the lumen of the duct constantly open.