To surgically manage hilar bile duct carcinoma successfully, it is important to be familiar with the principal anatomical variations of the biliary and vascular components of the plate system in the hepatic hilar area, because all the variations in the bile ducts and vessels occur in the plate system. The plate system consists of bile ducts and blood vessels surrounded by a sheath. There are three plates in the hilar area: the hilar plate, the cystic plate, and the umbilical plate. The bile duct and blood vessel branches penetrate the plate system and form Glisson's capsule in all segments of the liver, except for the medial segment. The right hepatic duct is usually (in 53%-72% of individuals) formed by the union of the anterior segmental duct and the posterior segmental duct in the hilar area. However, three other variations have been found in which these segmental ducts do not form the right hepatic duct. Few anatomical variations have been identified in the left hepatic duct, but confusion arises because of the variations in the medial segment ducts (B4) which join the left hepatic duct at different sites. In 35.5% of individuals they join the hepatic duct in the vicinity of the hilar confluence (type I B4 anatomy), and in 64.5% of individuals they join the left hepatic duct some distance away from the confluence (type II B4 anatomy). Because B4 is very close to the hilar confluence in type I, hilar bile duct carcinoma can easily invade B4 and, for that reason, for curative resection of hilar bile duct carcinoma, resection of S4a (the inferior part of the medial segment) should be considered along with the resection of extrahepatic bile duct and caudate lobe. Variations in the portal vein and hepatic artery are found in 16%-26% and 31%-33% of individuals, respectively. Because a considerable number of anatomical variations in the bile ducts and vessels persist in the hilar area, and the reported proportions of the different variations vary, it is necessary to have a good knowledge of the plate system and the variations in the bile ducts and blood vessels in the hilar area to perform safe and curative surgery for hilar bile duct carcinoma.
We analyzed various pre-, intra-, and postoperative variables in 100 consecutive patients treated by hepatectomy for various malignant and benign liver diseases to identify patients at risk of developing postoperative complications. Patients were divided into three groups: those with normal liver (NL, n = 53); those with liver cirrhosis (LC, n = 32); and those with obstructive jaundice (OJ, n = 15). The overall postoperative morbidity and mortality rates were 14% and 4% (due to liver failure), respectively. In the LC group the combined presence of abnormal levels of serum hyaluronic acid (HA, > 200 ng/ml), indocyanine green retention rate at 15 minutes (ICGR15, > 15%), and hepatic uptake ratio of (99m)Tc-galactosyl human serum albumin (GSA) at 15 minutes (LHL15, < 0.9) preoperatively was found to be a risk factor with a 100% morbidity rate. Operative blood loss of more than 1000 ml in LC patients was associated with high morbidity. In the OJ group preoperative parameters were almost normal after biliary drainage, but the extent of liver resection, blood loss > 2000 ml, and high serum interleukin-6 12 hours after hepatectomy correlated with high postoperative morbidity. No morbidity or mortality was reported in the NL group, except in a single patient who received long-term intraarterial chemotherapy preoperatively. Consequently, the extent of hepatectomy should be carefully determined according to the preoperative risk factors in LC patients; and in OJ patients hepatectomy, which tends to become extensive, should be carefully performed to minimize surgical stress because preoperative factors do not help predict outcome. Furthermore, the present study revealed that a serum HA level higher than 500 ng/ml on postoperative day 1 or day 7 (or both) was a useful marker for hepatic failure.
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