Anatomic Variation of Intrahepatic Bile Ducts in 300 Consecutive Liver Transplantation Donors on Intraoperative Cholangiograms Fig. 8. Unclassified or complex variation (type 7). Cholangiogram shows type-3 trifurcation, with the accessory right posterior seg- mental duct (arrowheads) pouring into the caudate branch of the bile duct. Large arrows=RPSD, small arrows=RASD, asterisks= LHD however, the conclusions to be drawn from these studies might be limited by the fact that the study groups involved included selected patients, referred for radiologic studies, and it was difficult to use ERCP or MRCP for detailed analysis of the bile duct anatomy. In our study, evaluation focused on the intraoperative cholangiograms of 300 con- secutive LDLT donors, who might represent a normal pop- ulation. We arbitrarily classified the branching pattern of IHDs according to the Cauinaud nomenclature, based on the re- lationship between the hepatic segmental duct, cystic duct, and the presence of an accessory duct. Our results showed that in the majority of the subjects (63%), the anatomy of the IHDs was type 1, or typical, a finding similar to that of earlier studies, in which the figure for this was 57 63% (2 4, 6, 7). While this type is considered the simplest, and ideal for harvesting where a right or left lobe is required for LDLT, the length of the RHD is an important factor. If this is short, the bile duct is likely to be easily injured dur- ing hepatic resection, and anastomosis between the donor’s liver and recipient’s bile duct or bowel is also likely to be difficult. In our study, the length of the first order branch ranged from 2.4 to 30 mm, and was less than 10 mm in 34% of donors. Among the seven types of anatomic variant, type 3A (drainage of the RPSD into the LHD) was the most com- mon, followed by type 2 (trifurcation), and these were pre- sent in 11% and 10% of donors, respectively. This finding is similar to that reported in previous studies: drainage of the RPSD into the LHD before its confluence with the RASD was found to occur in 13 19% of the population Korean J Radiol 4(2), June 2003 (7, 8). A knowledge of this anatomic variation is impor- tant, especially in performing percutaneous biliary proce- dures. Since it can result in drainage of the left side of the liver and posterior segment of right side (6), left-sided per- cutaneous transhepatic biliary drainage is preferable in pa- tients with periportal metastatic disease, in whom there is a risk of multiple segmental ductal obstructions. Moreover, in biliary disease such as hepatolithiasis, it is theorized that the ramification pattern of IHDs may affect hepatic biliary flow, leading to biliary stasis and subsequent secondary bacterial infection and recurrent pyogenic cholangitis (9). The fact that hepatolithiasis is more prevalent in the left lobe may well support this hypothesis (10). The LHD joins the CHD at a more acute angle than the RHD, and because the most acute angle is created between the RPSD and LHD in type 3A, such a patient is, in theory, likely to ex- perience more biliary stasis and a greater incidence of he- patic stone than those with other types. Accessory hepatic ducts have been reported in approxi- mately 2% of donors and may originate from either the left or right ductal system, along which they run. They may present as a solitary finding or in conjunction with other types of IHD variation (4). In our study, accessory hepatic ducts, which included type 5A, type 5B and two type-7, were observed in 18 patients (6%). Although accessory ducts are a minor aspect of variation, they should not be overlooked in liver transplantation or hepatic resection performed for other reasons. Intraoperative identification of accessory ducts and appropriate tailoring of the surgical technique are important if serious complications such as biloma or bile leakage are to be avoided. Because electro- cautery may seal an accessory duct temporarily, even with careful inspection of the cut margin of the liver, an aware- ness of possible variation in an accessory duct is important (5). The first-order branch of the LHD was absent in 1% of our subjects, in whom bile from segment II and III drained independently into the RHD and CHD, respectively. At hepatic surgery, separate anastomoses are also needed, and require an exact understanding of this variant, in which segment III of the bile duct is intraparenchymally located, as is segment IV. During hepatic hilar dissection, the extra- hepatic portion of segment II is visualized at the hilar re- gion, and can easily be misinterpreted as the LHD. Without knowledge of this variation, segment III of the bile duct may be ligated and sacrificed (3). In six cases, we encountered a variant form in which the RPSD drained into the cystic duct, and one in which the RHD drained into that same duct. It has been reported in the literature that the incidence of this anatomic variation, known as “cysticohepatic ducts”, is 1 2% (11, 12). Huang 89