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.     

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.     

Distributing pattern of the bile duct of the caudate lobe on computed tomography with drip infusion cholangiography and its surgical significance

BACKGROUND/AIMS: It is important to recognize the distribution of the bile ducts in the caudate lobe of the liver for the hepato-biliary surgery. To map the spatial relationship between the bile ducts and the liver parenchyma under physiological conditions, we performed an anatomical analysis of them using computed tomography combined with drip infusion cholangiography (DIC-CT). METHODOLOGY: We identified the bile ducts in the caudate lobe, which was divided into the Spiegel lobe, paracaval portion, and caudate process, with DIC-CT. We then investigated their number and confluence pattern in 132 patients without any abnormality in the hilar bile ducts. RESULTS: The mean number of the bile ducts in the caudate lobe was 2.68 per liver. In the Spiegel lobe, the branches drained into the left hepatic duct system in about 83%. The confluence of the paracaval branch was the left hepatic duct, right hepatic duct, and posterior segmental branch, all with the same frequency of approximately 30%. Almost all of the caudate process branches (92.4%) drained into the posterior segmental branch. CONCLUSIONS: DIC-CT is a useful method for the anatomical analysis of the intrahepatic bile ducts under physiological conditions, and we obtained novel and important findings for surgery.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Hepatectomy for cholangiocarcinoma complicated with right umbilical portion: anomalous configuration of the intrahepatic biliary tree

The right umbilical portion (right‐sided round ligament) has been discussed as an intrahepatic portal venous anomaly associated with “left‐sided gallbladder” in several reports. We treated two patients with right umbilical portion (RUP) associated with cholangiocarcinoma. Left hepatectomies were performed, preserving the residual hepatic blood flow and biliary continuity. From our experience in these patients we propose the presence of anomalous configuration of the intrahepatic biliary tree in RUP, because both patients showed medial segmental bile ducts ramified from the right and left hepatic ducts. In general, although the medial segmental bile duct ramified from the left, we surmised that this abnormal bilateral drainage pattern may not be a rare phenomenon in RUP. Special attention may be required to focus on the anatomy of the portal tributaries and biliary ramifications in RUP.     

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%).     

Anomalous connection of the right hepatic duct into the cystic duct: utility of magnetic resonance cholangiopancreatography

A 41-year-old female was admitted to our hospital for treatment of uterus carcinoma. Abdominal ultrasound showed gallbladder stones. Although magnetic resonance cholangiopancreatography revealed the right intrahepatic bile ducts, left hepatic duct and the common bile duct, the confluence of the right and left hepatic ducts was not visualized. At surgery, intra-operative cholangiography showed a biliary anomaly of the right hepatic duct entering the cystic duct. Subsequently cholecystectomy was accomplished without any injury to the bile duct. Our case may be the eighth such case of this rare biliary anomaly. When magnetic resonance cholangiopancreatography does not show the confluence of the right and left hepatic ducts, biliary anomaly of the right hepatic duct should be suspected and careful dissection should be performed from the Hartman's pouch, followed by intraoperative cholangiography, in order to avoid unnecessary injury to the bile duct.     

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.     

Hepatic parenchymal atrophy induction for intractable segmental bile duct injury after liver resection

Liver resection can result in various types of bile duct injuries but their treatment is usually difficult and often leads to intractable clinical course. We present an unusual case of hepatic segment III duct (B3) injury, which occurred after left medial sectionectomy for large hepatocellular carcinoma and was incidentally detected 1 week later due to bile leak. Since the pattern of this B3 injury was not adequate for operative biliary reconstruction, atrophy induction of the involved hepatic parenchyma was attempted. This treatment consisted of embolization of the segment III portal branch to inhibit bile production, induction of heavy adhesion at the bile leak site and clamping of the percutaneous transhepatic biliary drainage (PTBD) tube to accelerate segment III atrophy. This entire procedure, from liver resection to PTBD tube removal took 4 months. This patient has shown no other complication or tumor recurrence for 4 years to date. These findings suggest that percutaneous segmental portal vein embolization, followed by intentional clamping of external biliary drainage, can effectively control intractable bile leak from segmental bile duct injury.     

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.     

Left-Sided gallbladder with intrahepatic portal venous anomalies

The congenital anomaly in which the gallbladder is found on the left of the round and falciform ligaments (left-sided gallbladder) is rare. We report two patients with left-sided gallbladder in whom intrahepatic portal venous anomalies were identified. Computed tomography and intraoperative ultrasonography were used to define the portal venous anomaly. A long straight left main portal vein was demonstrated, which did not have the typical umbilical portion. The right anterior segmental portal branch (case 1), or the right main portal vein (case 2) were shown to course in a ventral direction and terminate as a cul de sac. The round ligament (right round ligament) was attached to this venous termination, forming the right umbilical portion. The left medial segmental portal venous branches originated from the right umbilical portion, and coursed to the left. In contrast, cholangiography disclosed that the left medial segmental bile duct coursed to the right after arising from the left hepatic duct (case 1), or the common hepatic duct (case 2). The essence of this anomalous condition is not a left-sided gallbladder, but a right round ligament, which is an embryologic abnormality of the umbilical vein. A review of the English language literature revealed no reports of left-sided gallbladder with intrahepatic portal venous anomalies.     

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.     

Intrahepatic segmental bile duct patterns in hepatolithiasis: a comparative cholangiographic study between Taiwan and Japan

Background/Purpose. We analyzed confluence patterns of intrahepatic segmental bile ducts, seeking to relate hepato-lithiasis to anatomic variation. The comparative study was completed patients with hepatolithiasis in Taiwan and Japan. Methods. Direct cholangiography was performed in 103 hepatolithiasis patients in Taiwan and 77 in Japan. Segmental ducts patterns were classified as type I, normal configuration; type II, “triad” confluence; type III, posterior segmental duct joining left hepatic duct; or type IV, distal confluence of the right posterior segmental duct. Results. Taiwanese patients had only calcium bilirubinate or black stones, and were mostly female. As overall analysis, types I, II, III, and IV were found in 61, 26, 13, and 3 patients, respectively. In Japanese, types I, II, III, and IV were found in 52, 10, 13, and 2, respectively. There was no difference between the two institutes. Since no patients in Taiwan had cholesterol calculi, Japanese patients were reanalyzed including only 58 patients with calcium bilirubinate or black stones. Differences in those populations remained insignificant. Conclusion. Anatomic variations in segmental ducts apparently do not contribute to pathogenesis of hepatolithiasis.     

Drainage area of the head of the pancreas by computed tomography under endoscopic retrograde pancreatography (ERP-CT).

BACKGROUND/AIMS: This study evaluated the drainage area of the capitular branches of the pancreas head by computed tomography under endoscopic retrograde pancreatography (ERP-CT). METHODOLOGY: ERP-CT was performed in 43 patients. The drainage area of the capitular branches of Wirsung's and Santorini's ducts were evaluated by dividing the pancreatic head into two areas, the anterior area and the posterior area. RESULTS: The pancreatic duct pattern was classified in 4 types; normal type, ansa type, loop type, and embryonic type. In normal type duct pattern, all inferior capitular branches of Wirsung's duct drained the posterior area and all inferior capitular branches of Santorini's duct drained the anterior area. In ansa type duct pattern, all inferior branches from Wirsung's duct drained the posterior area and inferior branches from Santorini's duct drained the anterior area and the posterior area. In loop type duct pattern, all inferior branches from Santorini's duct drained the posterior area and inferior branches from Wirsung's duct drained the anterior area and the posterior area. Middle capitular branches were detected only in normal B, normal C, and loop type. CONCLUSIONS: ERP-CT is a useful procedure that provided three-dimensional morphology of the capitular branch of the pancreas head.