Right Hepatic Duct

The right hepatic duct is one of the two main intrahepatic bile ducts responsible for collecting and draining bile from the right lobe of the liver. It is a short yet vital component of the biliary system, serving as the origin of the extrahepatic bile duct pathway. Formed by the confluence of anterior and posterior segmental ducts within the right liver lobe, the right hepatic duct joins the left hepatic duct at the liver hilum to form the common hepatic duct. Despite its small size, the duct has immense clinical relevance, particularly in surgical procedures such as liver resection, transplant, and bile duct repair, as well as in the classification and treatment of hilar cholangiocarcinoma.

Structure

The right hepatic duct is formed by the union of two major segmental ducts draining the respective functional segments of the right lobe:

• Anterior segmental duct: Drains segments V and VIII
• Posterior segmental duct: Drains segments VI and VII

These two ducts usually converge within the right liver near the porta hepatis to form the right hepatic duct, which then runs medially to join the left hepatic duct.

Basic Characteristics

Feature	Description
Length	Approximately 0.5 to 2.0 cm
Diameter	Typically 4–5 mm
Type	Intrahepatic, transitioning to extrahepatic just before merging with the left hepatic duct
Epithelium	Simple columnar epithelium with mucus-producing cells

Unlike arteries and veins, bile ducts lack smooth muscle in their wall and rely on passive pressure gradients and ductal peristalsis for bile transport.

Anatomical Variations

• Normal confluence: Right and left hepatic ducts form a short common hepatic duct
• Trifurcation: Right anterior, right posterior, and left hepatic ducts join simultaneously at the hilum (seen in ~15–20% of cases)
• Low insertion: Right posterior segmental duct may drain directly into the common hepatic duct or even the cystic duct

These variations are highly relevant in surgical planning and interventions to prevent iatrogenic injury.

Location

The right hepatic duct is located at the liver hilum, also known as the porta hepatis. It is embedded within the liver parenchyma and is surrounded by branches of the portal vein and hepatic artery.

Topographic Relationships

• Superior: Liver segments V and VIII
• Posterior: Right branch of the portal vein
• Anterior: Right branch of the hepatic artery
• Medial: Joins with the left hepatic duct to form the common hepatic duct

The confluence of the right and left hepatic ducts occurs anterior to the bifurcation of the portal vein and is enveloped in connective tissue alongside lymphatics and nerves. The ductal arrangement within the liver hilum follows a general pattern: bile duct anterior, artery intermediate, and portal vein posterior — often remembered by the acronym “BAP” (Bile duct, Artery, Portal vein).

Function

The primary function of the right hepatic duct is to collect and transport bile from the right lobe of the liver to the extrahepatic biliary system. It is a passive conduit, reliant on bile production pressure from hepatocytes and downstream peristalsis.

Bile Transport

• Receives bile from intrahepatic ductules of segments V–VIII
• Unites with the left hepatic duct to form the common hepatic duct
• Transports bile toward the gallbladder (via the cystic duct) or duodenum (via the common bile duct)

Directionality of Bile Flow

Under normal fasting conditions, bile is diverted from the common hepatic duct into the cystic duct and stored in the gallbladder. Upon eating, gallbladder contraction expels bile back through the cystic duct into the common bile duct and onward to the duodenum. The right hepatic duct is upstream of this process and remains a unidirectional entry point into the biliary tree.

Clinical Relevance

The right hepatic duct is of central importance in hepatobiliary pathology, radiology, and surgical procedures. Small injuries or anomalies involving this duct can lead to significant bile leakage or strictures.

1. Liver Resection and Transplant

• Right hepatectomy: Requires ligation of the right hepatic duct; surgeons must carefully differentiate it from segmental bile ducts
• Living donor transplant: Donor ducts are usually harvested with a portion of the right hepatic duct, requiring precise reconstruction

2. Bile Duct Injury

• Occurs commonly in cholecystectomy if anatomical variation is not recognized
• Injury to an aberrant right posterior duct can result in isolated segmental bile leaks

3. Cholangiocarcinoma (Klatskin Tumor)

Perihilar cholangiocarcinoma is a malignant tumor occurring at or near the confluence of the right and left hepatic ducts. Involvement of the right duct is a key criterion in staging and determines the extent of required surgical resection.

4. Imaging and Interventional Access

• MRCP (Magnetic Resonance Cholangiopancreatography): Helps visualize ductal anatomy and rule out obstruction
• Percutaneous transhepatic cholangiography (PTC): Often accesses the right hepatic duct for drainage or stent placement

5. Biliary Atresia and Congenital Anomalies

In neonates, absence or fibrous obliteration of the right hepatic duct (as part of biliary atresia) results in progressive cholestasis, requiring early diagnosis and intervention such as Kasai portoenterostomy or liver transplant.