Mastering Gallbladder and Bile Ducts anatomy: part 1
This video is an essential guide for mastering gall bladder and bile duct anatomy. The gallbladder is a pear-shaped organ located beneath the liver in a shallow depression on the inferior surface of the right hepatic lobe. It measures about 7 to 10 cm in length and has a capacity of 30 to 50 mL. The gallbladder is divided into four anatomical sections: the fundus, body, infundibulum (or Hartmann’s pouch), and neck, which leads into the cystic duct. The fundus is the widest and most distal part, often palpable when distended. The body lies between the fundus and the neck, which tapers into the cystic duct that ultimately connects with the common hepatic duct to form the common bile duct.
The cystic duct, around 2 to 4 cm long, contains spiral valves (Heister's valves), which may create a partial obstruction that regulates bile flow into and out of the gallbladder. Bile, produced by the liver, flows from the intrahepatic bile ducts to the hepatic ducts, then into the common hepatic duct, which joins the cystic duct from the gallbladder, forming the common bile duct. The common bile duct then runs towards the duodenum, where it joins the pancreatic duct and empties into the second part of the duodenum at the major duodenal papilla, controlled by the sphincter of Oddi.
Huang Classification of Bile Duct Anatomy
The Huang classification is an anatomical classification system that categorizes variations in the bile duct confluence. It is based on the branching patterns of the left and right hepatic ducts and their connections with the common hepatic duct and cystic duct. Huang’s classification is critical for understanding anatomical variations that can complicate biliary surgery or interventions like cholecystectomy and liver transplantation.
Type I: The classic anatomy, where the right and left hepatic ducts unite to form the common hepatic duct, which then joins with the cystic duct to form the common bile duct.
Type II: Here, the right posterior sectoral duct drains separately into the common hepatic duct instead of merging with the right hepatic duct.
Type III: In this type, the right anterior sectoral duct drains directly into the left hepatic duct, bypassing the usual right hepatic duct confluence.
Type IV: A rare variation where the right anterior and posterior sectoral ducts both drain independently into the common hepatic duct.
Type V: In this variation, the right hepatic duct drains into the cystic duct instead of the common hepatic duct.
Congenital Variations in Gallbladder Anatomy
Double Gallbladder: This rare variation involves the presence of two separate gallbladders, each with its cystic duct. They may share a common cystic duct or drain independently into the common bile duct.
Septate Gallbladder: This condition refers to a gallbladder divided into two or more chambers by septa.
Phrygian Cap: The gallbladder’s fundus folds back on itself, resembling a Phrygian cap. Although this condition is usually asymptomatic and incidental, it may sometimes be mistaken for a pathological lesion or complicate imaging interpretations.
Floating Gallbladder: In this condition, the gallbladder is suspended by a long mesentery, making it more mobile than usual.
Agenesis of the Gallbladder: This congenital absence of the gallbladder is extremely rare. In such cases, bile continues to flow directly from the liver to the small intestine without being stored, and patients may remain asymptomatic or experience symptoms similar to gallbladder disease due to associated bile duct abnormalities.
Ectopic Gallbladder: An ectopic gallbladder is a gallbladder located in an abnormal position, such as the left side of the liver, retrohepatic, or within the falciform ligament. This condition may complicate diagnostic imaging and surgical procedures, as the expected anatomical landmarks may not apply.
Understanding the variations in the anatomy of the gallbladder and bile ducts, as well as applying classifications like Huang’s, is crucial in clinical practice. These variations directly affect surgical techniques, imaging diagnostics, and managing bile duct injuries, ensuring better patient outcomes and minimizing complications.