Radiological anatomy of the medial segmental bile duct of the liver assessed by CT cholangiography

BACKGROUND/AIMS: To analyze drainage areas and points of confluence of the medial segmental bile ducts of the liver, 72 patients with obstructive jaundice underwent computed tomography cholangiography. METHODOLOGY: We divided the medial segmental ducts into the following three subsegmental branches: B4a was defined as the inferior branch, B4b as the superior branch, and B4c as the dorsal branch. RESULTS: In 62 (86%) of the 72 patients, each B4a and B4b branches joined to form a single medial segmental duct, which joined the left hepatic duct in 25 patients (35%), the confluence of the lateral inferior (B3) and superior (B2) branches in 18 patients (25%), B3 in 15 patients (20%), the confluence of the right and left hepatic ducts in 4 patients (6%). In addition, these medial segmental ducts primarily entered the left hepatic duct in the final half of its length or more distant portion from the hepatic hilum in 43 (77%) of the 62 patients. CONCLUSIONS: Thus, in most cases the inferior area of the medial segment should be preserved when right-sided resection of the liver is indicated for hilar bile duct cancer.