Location and Topography
The cystic duct is a component of the hepatoduodenal ligament (lig. hepatoduodenale), which occupies the rightmost border of the lesser omentum.
- Origin: Arises from the neck of the gallbladder (collum vesicae felleae), forming two curves in this region before directing upward and to the right.
- Termination: Unites with the common hepatic duct (ductus hepaticus communis) to form the common bile duct (ductus choledochus).
- Variations of union: The junction can form an acute or obtuse angle; parallel running alongside the common hepatic duct for some distance or a spiral course around it are also possible.
- Syntopy within the ligament: The proper hepatic artery (a. hepatica propria) lies to the left, and the portal vein (v. portae) lies posteriorly between the artery and the bile duct.
Wall Structure
The wall of the cystic duct has the following features:
- Muscular layer: Poorly developed, consisting of longitudinal and circular layers.
- Mucous membrane: Forms a spiral fold (plica spiralis).
- Submucosa: Mucous glands (glandulae mucosae ductulorum biliarium) are located within the walls of the extrahepatic bile ducts.
Function (Bile Flow Mechanism)
The cystic duct regulates bile transport depending on the phase of digestion:
- Between meals: The orifice of the common bile duct is closed, causing bile to flow retrogradely through the cystic duct into the gallbladder.
- During digestion: Bile is expelled through the cystic duct into the common bile duct and subsequently into the duodenum.
Clinical Significance: Biliary Colic
In cholelithiasis, a gallstone may impact within the cystic duct. This causes obstruction and reflex spasm, leading to increased intraluminal pressure and the development of biliary colic.
- Character of pain: Severe, bursting, and fairly constant. The term "colic" is not entirely accurate here because the pain lacks undulating waves of intensification, instead rapidly increasing and reaching a "plateau".
- Localization and radiation: Epigastrium and right upper quadrant; pain radiates to the right scapula, interscapular region, right shoulder, and right half of the neck.
- Trigger factors: Consumption of fatty or fried foods, unusually large meals after prolonged restriction, bumpy rides, trunk flexion, physical exertion, or psycho-emotional stress. It frequently occurs at night.
- Associated symptoms: Accompanied by nausea and vomiting that does not bring relief, as well as autonomic reactions such as blood pressure changes, tachycardia, or bradycardia.
Surgical Significance: Cholecystectomy
Isolation and transection of the cystic duct are critical steps during gallbladder removal (cholecystectomy).
- Critical View of Safety (CVS): The neck and lower third of the gallbladder body must be dissected from all sides, and the gallbladder separated from the hepatic bed. Structures should only be transected after confirming that exclusively two tubular structures—the cystic duct and the cystic artery (a. cystica)—enter the dissected area.
- Intraoperative diagnostics: A thin polyethylene catheter or special cannula is introduced through a small incision in the cystic duct to perform cholangiography, cholangiomanometry, or flow measurement.
- Stump management: The duct is ligated 0.5 cm away from its junction with the common bile duct.
- Do not ligate flush: There is a risk of narrowing the lumen of the common bile duct.
- Do not leave an excessively long stump: There is a risk of stump dilation and subsequent stone formation.