Abstract
The aim of this study is to make precise analysis of bile duct branches of the segment IX as defined by Couinaud. We investigate confluence patterns of b-c branch and d branch of segment IX in 104 patients without abnormal lesions at the hilar bile duct. The mean number of segment IX bile duct branch is 1.74. The b-c branch is observed in 94 cases and the d branch is observed in 61 cases. One b-c branch is seen in 59 cases, two b-c branches are seen in 26 cases, and 3 or more b-c branches are seen in 9 cases. The b-c branch connect with either a spiegel lobe (sp) branch or a caudate process (cp) branch in 38 cases. In contrast, d branch does not connect with sp branch or cp branch. The b-c branch joins to posterior duct in 39, right hepatic duct in 19, hilar bile duct in 38 and left hepatic duct in 25 patients, respectively. The all d branch joins peripheral posterior segmental bile ducts, and does not join any other segmental branch. The b-c branch extending to the diaphragmatic site is observed in only 29 cases. An increasing number of b-c branches is significantly associated with extension to diaphragmatic site. Conclusion: When patients with hilar bile duct cancer undergo radical resection, it is apparently unnecessary to resect the dorsal area of the right hepatic vein drained by d branch. The area drained by d branch is considered to be the posterior superior hepatic segment (S7).
