Anatomy of the hepatic hilar area: the plate system

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.     

Preoperative cholangiography of the caudate lobe: Surgical anatomy and staging for biliary carcinoma

The biliary branches of the caudate lobe (B1) join the right hepatic duct, the left hepatic duct, the confluence of these ducts, and/or the right posterior segmental bile duct. Therefore, in the preoperative staging of biliary tract carcinoma it is important to delineate the anatomy of B1 and the extent of cancer spread into B1. Tube cholangiography through percutaneous transhepatic biliary drainage or selective cholangiography by percutaneous transhepatic cholangioscopy enables us to obtain fine images of B1. We have developed cholangiography in the cephalad anterior oblique position to visualize B1 more clearly and distinctly. Four separate types of biliary branches are identified in the caudate lobe: (1) A duct running from the cranial portion of the right caudate lobe along the inferior vena cava to the hepatic hilus (B1r); (2) a duct from the cranial portion of the left caudate lobe to the hepatic hilus (B1ls); (3) a duct from the left lateral part of the left caudate lobe to the hepatic hilus (B1li); and (4) a duct from the caudate process to the hepatic hilus (B1c). The findings of the root of B1 in resected patients with biliary tract carcinoma were classified into four groups: not stenotic, short segmental stenosis, long segmental stenosis, and poorly imaged. A study of 64 branches of B1 in 42 resected patients with biliary tract cancer revealed carcinoma invasion in or near the root of B1 in all patients with poorly imaged or long segmental stenosis of B1, and in 33% of those with short segmental stenosis of B1.     

Resection of an icteric type hepatoma with tumor thrombi filling the right posterior bile duct

A 67-year-old male with jaundice was found to have hepatocellular carcinoma in the right hepatic lobe and tumor thrombi in the common hepatic duct. Physicians initially considered the tumor unresectable, and treated the patient with transcatheter arterial infusion chemotherapy and biliary endoprosthesis. The patient developed a liver abscess after the second transcatheter arterial infusion, and the physicians consulted our department for another form of therapy. Percutaneous transhepatic biliary drainage was performed to relieve revived obstructive jaundice. Cholangiography revealed tumor thrombi extending through the right posterior segmental bile duct into the common hepatic duct. Most biliary branches of the caudate lobe joined with the left lateral posterior segmental branch. Arterial and portal venous branches of the caudate lobe were not involved. Right hepatic lobectomy and extrahepatic bile duct resection were performed 1 year after initial diagnosis. On histologic examination, the epithelium of the right posterior segmental bile duct, which was filled with the tumor thrombi, was not detected. The patient is alive without recurrence 24 months after surgery. Careful investigation of biliary branches of the caudate lobe on cholangiography is essential to determine the necessity of caudate lobectomy in patients with hepatocellular carcinoma and tumor thrombi filling the right posterior segmental bile duct.     

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.     

Isolated caudate lobectomy by anterior approach for hepatocellular carcinoma originating in the paracaval portion of the caudate lobe

We aimed to assess isolated caudate lobectomy by the anterior approach for the treatment of large hepatocellular carcinomas originating in the paracaval portion of the caudate lobe. The surgical procedures consisted of ligation and dissection of the caudate branch of the portal vein and short hepatic veins from the right side of the hepatic hilum; liver resection cranially from the right side of the process portion; ligation and dissection of the short hepatic veins from the left side; hepatic resection between the lateral segment and Spiegel lobe; and, finally, dissection of the liver at the right of the Cantlie line, reaching the tumor in the paracaval portion of the caudate lobe. The important point in this procedure was the appropriate management of the short hepatic veins, the branches of the hepatic vein, and the glisson's vessels of the paracaval portion. The operative times for the three patients reported here were 430, 355, and 575 min, with blood loss of 1100, 1180, and 2000 ml, respectively. The duration of the operation was short and blood loss was minimal; severe complications were not observed. Complete recovery of liver function after this surgery tended to be slow. Early recurrence was observed during long-term follow-up. This procedure is considered to be a safe method, with optimal surgical vision for caudate lobe tumors of a relatively large size. However, adjuvant therapy to prevent recurrence is required.     

Right hepatic lobectomy and subsegmental resection of the left caudate lobe for gallbladder carcinoma involving the hepatic hilus: Preservation of the ventral portion of the left caudate lobe

A case of gallbladder carcinoma in a 75-year-old woman with familial hyperbilirubinemia and preoperative hepatic dysfunction is presented. Tube cholangiography through a percutaneous transhepatic biliary drainage (PTBD) catheter demonstrated a stricture and the hepatic confluence without filling of the gallbladder and showed two bile duct branches arising from the left caudate lobe. Cholangiography also disclosed that the left dorsal branch, which joined the right hepatic bile duct, was involved with tumor, while the left ventral branch, which joined the left hepatic duct, was not. Extended right hepatic lobectomy with resection of the dorsal portion of the left caudate lobe, preserving the ventral portion of the left caudate lobe, was performed. Postoperative cholangiography showed that the ventral branch of the left caudate lobe bile duct was preserved. Precise preoperative anatomic diagnosis of the biliary system in patients with hepatobiliary cancer allows successful subsegmental resection of the caudate lobe.     

Anomalous intrahepatic portal system in a patient with hilar bile duct cancer

We report a case of anomaly of the intrahepatic portal system in a 65-year-old man with hilar bile duct cancer. Preoperatively, percutaneous transhepatic portography demonstrated that there was a right posterior portal vein arising from the main portal vein. In addition, a large portal branch originated from the left portal vein and coursed toward the right hepatic lobe. Following portal embolization of the right posterior branch, the patient underwent an extended right hepatectomy with a caudate lobectomy. Intraoperatively, to the left at the porta hepatis and then it first gave off the right anterior portal vein originated from the left portal vein and coursed toward the right hepatic lobe horizontally behind the gallbladder and then separated into superior and inferior segmental branches to supply the right anterior segment of the liver. The ramification of some major branches without malposition of the gallbladder or round ligament was the important clinical feature of this anomaly.     

Surgical anatomy of the bile duct branches of the medial segment (B4) of the liver in relation to hilar carcinoma

In some patients, hilar bile duct carcinoma can easily spread to the bile duct branches of the caudate lobe (B1) as well as to the bile duct branches of the medial segment (B4), and resection of the inferior portion of the medial segment (S4a) is then required. It is therefore important to understand the detailed anatomy of the B4, its confluence patterns, and its relation to the B1 in order to be able to identify such patients. The confluence pattern of the B4 was studied in 141 specimens (68 adult cadavers and 73 liver casts) and the distance between the left bile duct branches of the caudate lobe (B11) and the B4 was measured in 56 of the 73 casts in which both B11 and B4 were present. Two main gross types of B4 were recognized: type I, in which B4 joined the left hepatic duct (LHD) close to the hilar confluence (35.5%), and type II, in which B4 joined the LHD far from the hilar confluence (54.6%). Analysis of the relationship between B11 and B4 revealed a mean distance between B11 and B4 of 8 mm in type 1, and 17 mm in type II. When the distance is less than 10 mm, B11 and B4 are considered to be located very close to each other, and in such individuals hilar bile duct carcinoma can infiltrate the B4 easily, thereby necessitating the resection of S4a, together with a caudate lobectomy for curative resection. Also, the confluence pattern of the B4 often creates a problem when the LHD is divided and reconstructed during hepatectomy, because of the numerous anatomical variations of the B4 itself. We therefore concluded that a good anatomical knowledge of the B4 and its relation to the B11 is essential in making the decision to perform S4a resection in selected patients with hilar bile duct carcinoma with the aim of curative resection.     

Surgical anatomy of the medial segment (S4) of the liver with special reference to bile ducts and vessels

BACKGROUND/AIMS: Resection of the inferior area of the medial segment (S4a) plus S5 with preservation of the superior area of the medial segment (S4b) is being performed to manage hilar bile duct carcinoma and pT2 type gallbladder carcinoma, and thus, attention has been focused on the surgical anatomy of the medial segment of the liver to identify the specific vessels and bile ducts of the areas of that segment to be resected and to be preserved. METHODOLOGY: Anatomical study of the bile duct, portal vein, middle hepatic vein, and middle hepatic artery to the medial segment branches of the liver (S4) was performed in a total of 171 specimens comprised of 71 adult cadavers, and 100 liver casts. RESULTS: 1) Two main types of bile duct branches of the medial segment (B4) were recognized. Type I included the branches which joined to the left hepatic duct on the hilar duct side (35.5%), and type II included the branches that joined on the peripheral side (54.6%). Several subtypes were also found in both types. The B2-B3 confluence was mostly on the left (41.7%) or posterior (42.7%) to the umbilical portion (UP) of the portal vein, and to the right of the UP (hilar side) in only 15.6%. 2) The portal vein of the medial segment branches (P4): P4a branched from the right angle and upper right border of the UP in every specimen. The most common morphology was 1 large and 2-3 small branches (41%). P4b was almost always found to branch posterior to the UP and lower than P4a, and the most common morphology was 1 large and 0-1 small branches (57.8%). 3) The middle hepatic vein: In 83.2% a common trunk was observed at the confluence with the inferior vena cava, and 8 types of the middle hepatic vein were recognized. 4) The middle hepatic artery: It arose from the left hepatic artery in 61.5%, from of the right hepatic artery in 27.5%, from the proper hepatic artery in 5.5%, and from both the left and the right hepatic artery in 5.5%. CONCLUSIONS: The detailed vascular and bile duct anatomy of S4 is described. This study should be helpful in identifying the specific vessels and bile ducts of the areas of the medial segment to be resected and to be preserved, thereby facilitating resection of the medial segment.     

A comparative study of the anatomy of rat and human livers

To compare the fundamental structure of the human liver, in relation to that of the rat a comparative study was performed, in which 20 rat livers and 78 human cadaver livers were examined. The rat livers had four lobes (left, middle, right, and caudate). The left and middle lobes formed a single lobe but the middle lobe had a deep notch to which the round ligament attached. The right lobe was split into two sub-lobes and the caudate lobe was divided into the paracaval portion and the Spiegel lobe, which was split into two sub-lobes. The left, right, and caudate lobes had one primary portal branch, whereas the middle lobe had two portal branches. The left and the right sub- and caudate lobes had one large hepatic vein each, whereas three large hepatic veins were observed in the middle lobe. Based on the ramifying patterns of the portal and hepatic veins, the rat middle lobe possessed left and right hepatic components and a main portal fissure. The following rat hepatic lobes were equivalent to the following human liver segments: the left lobe to segment II; the middle lobe to segments III, IV, V, and VIII; and the right lobe to segments VI and VII. The fundamental structures of rat and human livers were similar, and the findings demonstrated a new interpretation of the anatomy of the human liver.     

Left hepatectomy or left trisectionectomy with resection of the caudate lobe and extrahepatic bile duct for hilar cholangiocarcinoma (with video)

Purpose

Although left-sided hepatectomy, such as a left hepatectomy or left trisectionectomy with resection of the caudate lobe and extrahepatic bile duct, is used to treat hilar cholangiocarcinoma predominantly involving the left side of the hepatic hilum, it is associated with several difficult technical points. The important points during left-sided hepatectomy are described here.

Techniques

There are anatomical variations of the sectional artery and bile duct. It is essential to understand the individual intrahepatic and hilar anatomy preoperatively. Surgical procedures consist of lymph node clearance, dissection of the distal bile duct, skeletonization resection of the hepatoduodenal ligament, mobilization of the liver and liver resection, dissection of the intrahepatic bile ducts, and biliary reconstruction. During lymph node dissection and skeletonization resection of the hepatoduodenal ligament, the nerve plexus around the hepatic artery is dissected, and its adventitia is exposed with great care to avoid injuring the hepatic artery. Mobilization of the caudate lobe is performed only from the left side. There is no clear landmark between the caudate lobe and the right posterior section during liver resection. In the final step of liver resection, it progresses toward the right edge of the inferior vena cava. When dividing intrahepatic bile ducts, extreme care should be used to avoid injury to the corresponding hepatic arteries, especially the anomalous supraportal posterior sectional artery.

Conclusions

Left-sided hepatectomy for hilar cholangiocarcinoma should be considered a more complicated and technically demanding procedure than right-sided hepatectomy. Surgeons need to pay close attention to anatomical variations in order to perform a left-sided hepatectomy safely and successfully.     

Cholangiocellular carcinoma in the caudate lobe with intraluminal growth in the extrahepatic bile duct.

A case of cholangiocellular carcinoma in the caudate lobe with intraluminal growth in the extrahepatic bile duct is reported. The main tumor in the caudate lobe was detected by computed tomography and angiography, and two intraluminal tumors at the hepatic hilus and at the root of the right posterior segmental duct were well demonstrated by cholangiography and percutaneous transhepatic cholangioscopy. Independent total caudate lobectomy with bile duct resection was performed. Cholangiocellular carcinoma of the liver with intraluminal growth in the extrahepatic bile duct is very rare and has not been reported in the literature. Independent caudate lobe resection requires a rather complicated technique. However, this method has the advantage of reducing to a minimum the hepatic volume to be resected, and is useful for poor-risk patients or for cases with localized carcinoma at the hepatic hilus.     

Variations of intrahepatic and proximal extrahepatic bile ducts

BACKGROUND/AIMS: The modern segmental concept of the liver with a segmental bile duct distribution is of practical importance for biliary specialists and should include information on variations of intrahepatic and extrahepatic bile ducts. The aim of this study was to find biliary variations, especially on a segmental and sectorial level, and to try to arrange them into types. METHODOLOGY: We analyzed 51 corrosion casts of the human liver, which enabled the three-dimensional study of extrahepatic, sectorial, segmental and subsegmental bile ducts, their variations in course and confluencing, and the relationship between the structures of the portal pedicle. RESULTS: The types of confluence and their frequency were determined separately for the left, right, right anterior sectorial, right posterior sectorial and common hepatic ducts. "Normal" left confluence was formed in 82% and three variations in 18%. "Normal" right confluence was formed in 75% and four variations in 25%. A complete ("normal") anterior sectorial duct was present in 35% and four variations in 65%. A complete ("normal") posterior sectorial duct was present in 61% and four variations in 39%. CONCLUSIONS: The study showed that the biliary tree variations are quite frequent, and therefore clinically important, and that they could be arranged into several types.     

The paracaval segments of the liver

Two segments constitute thedorsal sector: I to the left and in front of the inferior vena cava, and IX in front and to the right of the cava; they are united inferiorly by the caudate process. Segment I includes the caudate lobe, and segment IX is incorporated in the posterior surface of the right liver. Small dorsal pedicles, which are quite numerous, arise from the posterior margin of the main portal elements, and ascend upward. Segment I receives twigs from the left or right livers, many from the right lateral pedicle (67 biliary branches enter the right lateral duct, the unique duct in three cases). Segment IX consists of three subsegments. IXb lies under the interval between the middle and right superior hepatic veins, in 40% of the cases examined the veins come from the left portal vein or the bifurcation, in 6 cases the ducts enter the left hepatic duct, in 40 cases the branches extend higher than the plane of the main hepatic veins, in 18 cases reaching the upper surface of the liver. IXc is under the right hepatic vein, and IXd is to the right of a vertical plane passing by the right superior vein. Hepatic veins, enter the cava directly, sometimes the middle or the left hepatic veins.     

Compensatory hepatic hypertrophy after occlusion of branches of the portal vein or bile duct

The effect on the liver of portal or bile duct branch occlusion was examined in rabbits by measuring hepatic tissue blood flow and cellular kinetics, using the bromodeoxyuridine labeling index. The portal branch bile duct branch, or both, to the main lobe and caudate lobe (80.4% of total liver weight) were ligated or embolized just above the right posterior lobe (19.6%), resulting in compensatory hypertrophy of the right posterior lobe and atrophy of the main and caudate lobes. Twenty-four days after ligation, the degree of compensatory hypertrophy in the different groups was comparable. There were significant differences in the pattern of the development of hypertrophy. Ligation of both a portal branch and the corresponding bile duct resulted in more rapid hypertrophy and atrophy than ligation of a portal branch alone. Ligation of a branch of the bile duct resulted in slow development of hypertrophy and atrophy. In the embolization group, the increase in the right posterior lobe stopped 6 days after the operation, resulting that it was about 40% thereafter. Histological findings showed that the fibrin clot had contracted and was floating in the portal branch to the main lobe. These results suggested that portal blood flow to the main lobe had resumed and was gradually increasing as the clot contracted. Portal branch ligation gave results superior to those with portal branch embolization with regard to application to preoperative procedure in extended hepatobiliary surgery.     

An unusual growth pattern of a mucin-producing intrahepatic cholangiocellular carcinoma involving the hepatic hilus.

The case of a mucin-producing intrahepatic cholangiocellular carcinoma in a 73 year-old-man is presented. A tumor originating in the right posterior inferior segment of the liver was found to be invading the right posterior and anterior bile ducts, and the hepatic hilus. Extensive superficial spread was observed in the entire posterior segmental bile duct extending to the hepatic hilus. Mucin produced and excreted by the tumor was retained in the common hepatic and common bile duct. The diagnosis in this case was suggested by percutaneous transhepatic aspiration of mucinous bile, and was confirmed by utilizing the techniques of ultrasonography, percutaneous transhepatic cholangiography, computed tomography and angiography. Curative surgery, which included right hepatic lobectomy with total caudate lobectomy and bile duct resection, was performed. Biliary continuity was maintained by left hepaticojejunostomy using a Roux-en-Y jejunal loop. The histological diagnosis was mucin-producing papillary adenocarcinoma originating in the right posterior inferior segment of the liver. Postoperative recovery was very good and the patient has now been enjoying a good active social life for the last 20 months with no signs of tumor recurrence. This case report discusses the unusual growth pattern of a mucin-producing intrahepatic cholangiocellular carcinoma involving the hepatic hilus, and suggests rational surgical treatment.     

Primary cholesterol hepatolithiasis

Stones extracted from patients with hepatolithiasis were analysed by infrared spectrophotometry. Cholesterol stones containing 70% or more cholesterol were found in 12 out of 55 cases. Judging from the lodging site of the stones, the degree of dilatation of the cystic duct, and the presence of cholecystitis, five of the cases were considered to be cholesterol stones produced in the liver. Two out of the five cases were a 44-year-old female and a 46-year-old female, respectively, with normal bifurcation of intrahepatic ducts, and stones were found in the lateral branches of dilated cystic bile ducts. The other three were 2 males and 1 female with an average age of 33. In these cases, the posterior descending branch bifurcated from the left hepatic duct, and stones were lodged in the dilated bile ducts distal to the junction of the left hepatic duct and the posterior descending branch. It is our conclusion that at least the former two were cases of “primary cholesterol hepatolithiasis” in view of the shape of the stones conforming to the hepatic duct, their easy morcellation, and the high cholesterol contents.     

Carcinoma of the hepatic hilus with superficial spreading to the intrahepatic segmental bile ducts: Report of a case

A case of superficially-spreading carcinoma of the hepatic hilus is presented. Percutaneous transhepatic biliary drainage was performed to alleviate jaundice and to evaluate the biliary system. A nodular tumor originating in the upper part of the common hepatic duct was found to be invading the confluence of the right and left hepatic ducts. Extensive superficial spread was observed in the proximal portion of the right anterior superior, right anterior inferior, right posterior superior, right posterior inferior, and caudate bile duct branches. Preoperative surgical planning was carried out on the basis of an evaluation of the findings of ultrasonography, computed tomography, percutaneous transhepatic cholangiography, and percutaneous transhepatic cholangioscopy. Absolute curative surgery, which included right hepatic lobectomy with total caudate lobectomy and bile duct resection, was performed. Bilioenteric continuity was reestablished with a Roux-en-Y jejunal loop. The histological diagnosis was well-differentiated tubular adenocarcinoma of the common hepatic duct. Postoperative recovery was very good; the patient has now enjoyed a good active social life for the past 4 years and 10 months, with no signs of recurrence. In this case report, we discuss the precise preoperative diagnosis and rational surgical treatment for carcinoma of the hepatic hilus with superficial spread.     

Left hepatic trisegmentectomy for intraductal papillary cholangiocarcinoma: report of a case

We present a rare case of intraductal papillary cholangiocarcinoma in a 69 year-old man which was treated with left hepatic trisegmentectomy. The hepatic bile ducts were dilated by intraductal masses, which had extended into the intrahepatic bile ducts without involvement of the posterior inferior segmental duct (B6). The patient underwent left hepatic trisegmentectomy with hilar duct resection. The tumors in the posterior superior segmental duct (B7) were resected and biliary reconstruction was performed with a jejunal loop. Post-operative recovery was good, and the patient survived for 7 months after surgery.     

Anatomic variations in intrahepatic bile ducts in a north Indian population

Background and Aim:  In the present study, we described the anatomical variations in the branching patterns of intrahepatic bile ducts (IHD) and determined the frequency of each variation in north Indian patients. There are no data from India.
Methods:  The study group consisted of 253 consecutive patients (131 women) undergoing endoscopic retrograde cholangiograms for different indications. Anatomical variations in IHD were classified according to the branching pattern of the right anterior segmental duct (RASD) and the right posterior segmental duct (RPSD), presence or absence of first-order branch of left hepatic duct (LHD) and of an accessory hepatic duct.
Results:  Anatomy of the IHD was typical in 52.9% of cases ( n  = 134), showing triple confluence in 11.46% ( n  = 29), anomalous drainage of the RPSD into the LHD in 18.2% ( n  = 46), anomalous drainage of the RPSD into the common hepatic duct (CHD) in 7.1% ( n  = 18), drainage of the right hepatic duct (RHD) into the cystic duct 0.4% ( n  = 1), presence of an accessory duct leading to the CHD or RHD in 4.7% ( n  = 12), individual drainage of the LHD into the RHD or CHD in 2.4% ( n  = 6), and unclassified or complex variations in 2.7% ( n  = 7). None had anomalous drainage of RPSD into the cystic duct
Conclusion:  The branching pattern of IHD was atypical in 47% patients. The two most common variations were drainage of the RPSD into the LHD (18.2%) and triple confluence of the RASD, RPSD, and LHD (11.5%).