Preliminary study of the anatomy of the venous drainage of the intrahepatic and extrahepatic bile ducts and its relevance to the practice of hepatobiliary surgery.

BACKGROUND: Although there have been many studies of the arterial supply of the biliary system, attempts to study the corresponding venous drainage have been few and all have been incomplete. The purpose of the present investigation is to describe the anatomy of the venous drainage of both the intrahepatic and extrahepatic bile ducts and to determine its relevance to hepatobiliary surgery.
METHODS: The intrahepatic and extrahepatic venous drainage of the bile ducts was investigated in seven specimens by injecting a solution of 10% gelatin coloured with Alcian blue into the portal vein or the superior mesenteric vein to outline the venous drainage. The specimens were dissected under loop magnification and representative drawings were obtained.
RESULTS: The surface of the intrahepatic and extrahepatic bile ducts was covered by a fine venous plexus. On the surface of the supraduodenal common hepatic duct and common bile duct the venous plexus drained laterally into marginal veins, usually two in number and known as the 3 o'clock and 9 o'clock marginal veins. Inferiorly the marginal veins and the venous plexus communicated with the pancreaticoduodenal venous plexus, which in its turn drained into the posterosuperior pancreaticoduodenal vein, a branch of the superior mesenteric vein. Superiorly the marginal veins divided into a number of branches. Some branches followed the left and right hepatic ducts into the liver, communicating with the venous plexus and the adjacent branches of the portal vein. Other branches of variable size entered either segment IV or the caudate lobe or process via the hilar venous plexus. A most important finding was that even after dividing the bile duct and all communicating veins at the upper border of the duodenum, the venous plexus and the marginal veins filled normally to the level of transection. This occurred almost certainly by retrograde filling from above.
CONCLUSION: The satisfactory results of end-to-end anastomosis in whole liver transplantation depends partly on the presence of adequate venous drainage. This has been amply demonstrated by the injection studies. This would indicate that the poor results of end-to-end repair of the bile duct after surgical trauma results from other factors such as poor technique, devascularization of the cut ends due to trauma, and carrying out the anastomosis under tension. After resection of the hilum for cholangiocarcinoma the venous drainage of the left and right hepatic ducts and their branches depends mainly on the communications between the venous plexus on the ducts and the adjacent branches of the portal vein, even at a lobular or sinusoidal level. The satisfactory results obtained after anastomosis of the left and right hepatic ducts or their branches to a Roux loop ofjejunum attest to this. This applies also to the transplantation of segments II and III in paediatric patients from related adult donors and in patients receiving split liver transplants. Finally, the venous drainage at the bifurcation of the common hepatic duct has been shown to enter the caudate lobe and segment IV directly. This suggests that a hilar cholangiocarcinoma may metastasize to these segments, and perhaps partly explain the significantly better long-term results when the caudate lobe and segment IV are resected en bloc with the cholangiocarcinoma as part of modern radical surgery for this condition.