Variations in extra-hepatic biliary tree morphology and morphometry: a narrative review of literature with focus on cystohepatic triangle

The morphometry and morphology of the components of extrahepatic biliary tree show extensive variations. A beforehand recognition of these variations is very crucial to prevent unintended complications while performing surgeries in this region. This study was conducted to analyse the configuration of the extrahepatic biliary tree and its possible variations, as well as measure the components that limit the cystohepatic triangle. Articles were searched in major online indexed databases (Medline and PubMed, Scopus, Embase, CINAHL Plus, Web of Science and Google Scholar) using relevant key words. A total of 73 articles matched the search criteria of which 55 articles were identified for data extraction. The length of left and right hepatic duct in majority of studies was found to be > 10 mm. A wide range of diameters of hepatic ducts were observed between 5 and 43 mm. The average length of cystic duct is around 20 mm. The length and diameter of the common bile duct are 50-150 mm and 3-9 mm, respectively. The most frequently observed pattern of insertion of cystic duct into common hepatic duct is right lateral, rarely anterior, or posterior spiral insertion can present. The results of this study will provide a standard reference range which instead will help to differentiate the normal and pathological conditions.

Effectiveness of near-infrared fluorescent cholangiography in the identification of cystic duct-common hepatic duct anatomy in comparison to magnetic resonance cholangio-pancreatography: a preliminary study

INTRODUCTION

Bile duct injury represents the most serious complication of LC, with an incidence of 0.3-0.7% resulting in a significant impact on quality-of-life, overall survival, and frequent medico-legal litigations. Near-infrared fluorescent cholangiography (NIRF-C) represents a novel intra-operative imaging technique that allows a real-time enhanced visualization of the extrahepatic biliary tree by fluorescence. The role of routine use of pre-operative magnetic resonance cholangio-pancreatography (MRCP) to better clarify the biliary anatomy before laparoscopic cholecystectomy is still a matter of debate. The primary aim of this study was to evaluate the effectiveness of NIRF-C in the detection of cystic duct-common hepatic duct anatomy intra-operatively in comparison with pre-operative MRCP.

METHODS

Data from 26 consecutive patients with symptomatic cholelithiasis or chronic cholecystitis, who underwent elective laparoscopic cholecystectomy with intra-operative fluorescent cholangiography and pre-operative MRCP examination between January 2018 and May 2018, were analyzed. Three selected features of the cystic duct-common hepatic duct anatomy were identified and analyzed by the two different imaging methods: insertion of cystic duct, cystic duct-common hepatic duct junction, and cystic duct course.

RESULTS

Fluorescent cholangiography was performed successfully in all twenty-six patients undergoing elective laparoscopic cholecystectomy. The visualization of cystic duct was reported in 23 out of 26 cases, showing an overall diagnostic accuracy of 86.9%. The level of insertion, course, and wall implantation of cystic duct were achieved by NIRF-C with diagnostic accuracy values of 65.2%, 78.3%, and 91.3%, respectively in comparison with MRCP data. No bile duct injuries were reported.

CONCLUSION

Fluorescent cholangiography can be considered a useful imaging diagnostic tool comparable to MRCP for detailed intra-operative visualization of the cystic duct-common hepatic duct anatomy during elective laparoscopic cholecystectomies.

A novel classification of aberrant right hepatic ducts ensures a critical view of safety in laparoscopic cholecystectomy

BACKGROUND

Based on the spatial relationship of an aberrant right hepatic duct (ARHD) with the cystic duct and gallbladder neck, we propose a practical classification to evaluate the specific form predisposing to injury in laparoscopic cholecystectomy (LC).

METHODS

We retrospectively investigated the preoperative images (mostly magnetic resonance cholangiopancreatography) and clinical outcomes of 721 consecutive patients who underwent LC at our institute from 2015 to 2018. We defined the high-risk ARHD as follows: Type A: communicating with the cystic duct and Type B: running along the gallbladder neck or adjacent to the infundibulum (the minimal distance from the ARHD < 5 mm), regardless of the confluence pattern in the biliary tree. Other ARHDs were considered to be of low risk.

RESULTS

A high-risk ARHD was identified in 16 cases (2.2%): four (0.6%) with Type A anatomy and 12 (1.7%) with Type B. The remaining ARHD cases (n = 34, 4.7%) were categorized as low risk. There were no significant differences in the operative outcomes (operative time, blood loss, hospital stay) between the high- and low- risk groups. Subtotal cholecystectomy was applied in four cases (25%) in the high-risk group, a significantly higher percentage than the low-risk group (n = 1, 2.9%). In all patients with high-risk ARHD, LC was completed safely without bile duct injury or conversion to laparotomy.

CONCLUSIONS

Our simple classification of high-risk ARHD can highlight the variants located close to the dissecting site to achieve a critical view of safety and may contribute to avoiding inadvertent damage of an ARHD in LC.

Unique origin of the cystic artery

The cystic artery (CA) is known to exhibit variations in its origin and branching pattern. This is attributed to the developmental changes occurring in the primitive ventral splanchnic arteries. During routine dissection of a male cadaver, we observed that the CA originated from the middle hepatic artery (MHA) at a distance of about 1 cm from its origin, and the MHA originated from the right hepatic artery at a distance of 2.1 cm from its origin. The CA traversed for a distance of 1.5 cm, giving off a branch to the cystic duct. It then passed anterior to the cystic duct. The origin of the CA was located to the left of the common hepatic duct, outside the Calot's triangle. The topographical anatomy of the arterial system of the hepatobiliary region and their anomalous origin should be considered during hepatobiliary surgeries. This knowledge is also important for interventional radiologists in routine clinical practice.

[Anatomical variations of roots of the common bile duct]

Variations of extrahepatic bile ducts are the basis of hepatobilliar surgery, and they may be a problem during the surgical procedures. In this paper we present the results of our research, wich is conducted on 100 human livers. Common hepatic duct wich is formed by connecting of right hepatic duct and left hepatic duct is noticed in 92% of cases, and in 5% of cases was formed by tree bile ducts. Aberant bile ducts was found in 3% of total number of examined.

Optimizing the critical view of safety in laparoscopic cholecystectomy by clipping and transecting the cystic artery before the cystic duct

Might prevent bile duct injury

Magnetic resonance cholangiopancreatography of biliary system abnormalities in children

OBJECTIVE

The aim of this study was to assess the usefulness of magnetic resonance cholangiopancreatography (MRCP) with a single-shot fast spin-echo sequence as a noninvasive method to evaluate the biliary system in children.

METHODS

Twenty-five MRCP examinations of 23 patients were evaluated. On the basis of surgical (n=5), endoscopic retrograde cholangiopancreatography (n=4), liver biopsy (n=4), clinical data, and follow-up observation, 6 children were considered to have no significant abnormality. The other 17 children were found to have pancreaticobiliary disease, including choledochal cyst, biliary system dilatation, choledocholithiasis, biliary atresia, multiseptated gallbladder, anomalous pancreaticobiliary union, ruptured hydatic cyst, and biloma. The findings were correlated with the ultrasonography, computed tomography, surgical, and endoscopic retrograde cholangiopancreatography results.

RESULTS

Magnetic resonance cholangiopancreatography showed the first branch of the intrahepatic duct, the common hepatic duct, the gallbladder, and the common bile duct in 14 children. Cystic duct was not seen in infants, but was partially visible in younger children. Although the main pancreatic duct was visible in head and body portions in 65% of the patients, it was visible in 17% of the patients in the tail. The diagnostic accuracy of MRCP was 100% in patients with choledochal cysts and stenoses. In a patient with hydatic cyst, cystobiliary communication was successfully demonstrated.

CONCLUSION

Magnetic resonance cholangiopancreatography can be used effectively for the evaluation of the biliary system in children.

Contrast-enhanced magnetic resonance cholangiography with Gd-BOPTA and Gd-EOB-DTPA in healthy subjects

PURPOSE

To evaluate the biliary enhancement dynamics of the two gadolinium chelates Gd-BOPTA (MultiHance) and Gd-EOB-DTPA (Primovist) in normal healthy subjects.

MATERIAL AND METHODS

Ten healthy volunteers were evaluated with both agents by magnetic resonance (MR) imaging at 1.5T using a breath-hold gradient-echo T1-weighted VIBE sequence. The relative signal intensity (SI) differences between the common hepatic duct (CHD) and liver parenchyma were measured before and 10, 20, 30, 40, 130, 240, and 300 min after contrast medium injection.

RESULTS

Biliary enhancement was obvious 10 min post-injection for Gd-EOB-DTPA and was noted at 20 min for Gd-BOPTA. At 40 min delay, Gd-BOPTA reached its peak biliary enhancement, but at neither 30 nor 40 min delay was there any significant difference compared with that of Gd-EOB-DTPA. At later delays, the contrast between CHD and liver continued to increase for Gd-EOB-DTPA, whereas it decreased for Gd-BOPTA.

CONCLUSION

The earlier onset and longer duration of a high contrast between CHD and liver for Gd-EOB-DTPA facilitates examination of hepatobiliary excretion. Therefore, Gd-EOB-DTPA may provide adequate hepatobiliary imaging within a shorter time span than Gd-BOPTA and facilitate scheduling at the MR unit. Further studies in patients are required to compare the imaging advantages of Gd-EOB-DTPA and Gd-BOPTA in clinical practice.

Microvascularization of the canine hepatic ducts

The angioarchitecture of the proximal and distal segments of the hepatic duct in the dog was investigated by means of vascular corrosion casts under a scanning electron microscope. The results of observations indicated a change of the pattern of vascularization of the hepatic duct along with the increasing distance of the hepatic duct from the liver and increasing diameter of the duct. In the proximal hepatic duct, the main blood vessels run along the duct as a pair of supplying arteriole and voluminous collecting venule, while in the distal segments of the hepatic duct on the opposite margin of the duct two vascular triads were observed, composed of two venules and one medial arteriole. On the surface of both segments of the hepatic duct, there are well-anastomosed outer venous plexuses. In the distal segments of the hepatic duct, the outer venous plexus accompanies a fine outer arterial rete. Observations of the intramural network indicate the presence of single terminal arterioles running to mucosa and supplying a subepithelial capillary network. Differences were observed in the blood drainage from the mucosa, as in the proximal segment of the hepatic duct single post-capillary venules are found, while in the distal segment in the mucosa a well-developed mucosal venous plexus is formed. In the well-developed venous system of the hepatic duct no valves were observed.

Gadobenate dimeglumine as an intrabiliary contrast agent: comparison with mangafodipir trisodium with respect to non-dilated biliary tree depiction

OBJECTIVE

To compare the efficacy of Mangafodipir trisodium (Mn-DPDP)-enhanced MR cholangiogrphy (MRC) and Gadobenate dimeglumine (Gd-BOPTA)-enhanced MRC in visualizing a non-dilated biliary system.

MATERIALS AND METHODS

Eighty-eight healthy liver donor candidates underwent contrast-enhanced T1-weighted MRC. Mn-DPDP and Gd-BOPTA was used in 36 and 52 patients, respectively. Two radiologists reviewed the MR images and rated the visualization of the common duct, the right and left hepatic ducts, and the second-order branches using a 4-point scale. The contrast-to-noise ratio (CNR) of the common duct to the liver in the two groups was also compared.

RESULTS

Mn-DPDP MRC and Gd-BOPTA MRC both showed similar visualization grades in the common duct (p=.380, Mann-Whitney U test). In the case of the proximal bile ducts, the median visualization grade was significantly higher with Gd-BOPTA MRC than with Mn-DPDP MRC (right hepatic duct: p=0.016, left hepatic duct: p=0.014, right secondary order branches: p=0.006, left secondary order branches, p=0.003). The common duct-to-liver CNR of the Gd-BOPTA MRC group was significantly higher (38.90+/-24.50) than that of the Mn-DPDP MRC group (24.14+/-17.98) (p=.003, Student's t test).

CONCLUSION

Gd-BOPTA, as a biliary contrast agent, is a potential substitute for Mn-DPDP.

Intraoperative cholangiography: past, present, and future

The extrahepatic biliary tree was first visualized in 1918 when Reich injected bismuth and petrolatum and defined a biliary fistula, thus opening the field for further studies of the biliary tree. Mirizzi recorded the first series of intraoperative cholangiography in 1932 using static films. Later, the mobile C-arm image intensifier using a TV monitor was reported in a series by Berci and colleagues in 1978. They emphasized the importance of using routine cholangiography in all laparoscopic cholecystectomies. This procedure can be performed through the cystic duct or through the gallbladder with excellent visualization of the anatomy of the extrahepatic biliary tree, including the potential of finding bile duct stones, stricture, and tumor, as well as defining the function and anatomy of Oddi's sphincter. Numerous benefits of this technique can be observed, including early definition of a bile duct leak or injury. X-ray resolution will continue to improve as well as three-dimensional imaging, and intraoperative magnetic imaging cholangiopancreatography may be developed as the future intraoperative cholangiogram.

Cystic duct and Heister's "valves"

The anatomy and physiology of the cystic duct have been relatively neglected by anatomists and the function of the spiral mucosal folds or "valves" of Heister, first described in 1732, remains obscure. The gross and microscopic anatomy of the cystic duct is reviewed together with results from laboratory investigations into the function of the cystic duct and its spirally arranged folds. The duct and spiral folds contain muscle fibers responsive to pharmacologic, hormonal, and neural stimuli. There is, however, no convincing evidence of a discrete muscular sphincter within the duct. Although the cystic duct is unlikely to play a major role in gallbladder filling and emptying, it appears to function as more than a passive conduit. Coordinated, graded muscular activity in the cystic duct in response to hormonal and neural stimuli may facilitate gallbladder emptying. The principal function of the internal spiral folds that are found in man and other animals may be to preserve patency of this narrow, tortuous tube rather than to regulate bile flow.

Spiegel?s Lobe Bile Ducts Often Drain into the Right Hepatic Duct or Its Branches: Study Using Drip-Infusion Cholangiography-Computed Tomography in 179 Consecutive Patients

Using drip-infusion cholangiography-computed tomography (DIC-CT), we successfully identified the bile ducts draining the caudate lobe in 138 of 179 consecutive patients with extrahepatic cholelithiasis (179 ducts from Spiegel's lobe and 154 from the paracaval portion; 1-5 ducts per patient). The dorsal subsegmental duct of S8 (B8c) was often identified and could be discriminated from the paracaval caudate ducts, thus acting as a landmark for the right margin of the caudate lobe. Notably, in more than one-third of the 138 patients, at least one of the Spiegel's lobe ducts drained into the right hepatic duct or its branches (30.2% of the 179 ducts overall; all ducts joined branches of the right lobe in 25 patients). Similarly, 34.4% of the 154 paracaval caudate lobe ducts drained into the left hepatic duct or its branches. These "anatomical left/right dissociations" between the drainage territory and route were much more frequent than previously reported. Our results confirm the effectiveness of DIC-CT as a classical, noninvasive method for presurgical evaluation of the biliary system, but they also suggest that anatomical partial resection of the dorsal liver in patients with hilar cholangioma is often impossible because of contralateral biliary drainage.

MR cholangiopancreatography: improved ductal distention with intravenous morphine administration

Magnetic resonance (MR) cholangiopancreatography has proved a robust and noninvasive imaging modality for evaluating the biliary and pancreatic ducts without the use of ionizing radiation. Although MR cholangiopancreatography reliably depicts the main extrahepatic and intrahepatic bile ducts, it does not depict the segmental intrahepatic ducts unless they are dilated. The segmental ducts are difficult to visualize with MR cholangiopancreatography because of their small caliber and the limited spatial resolution and signal-to-noise ratio achievable with standard MR pulse sequences. However, visualization of the normal (ie, nondistended) biliary system is necessary for the evaluation of donor candidates for living related liver transplantation. Because of the prevalence of variant biliary anatomy, MR cholangiopancreatography is often used for preoperative evaluation of prospective liver donors. Intravenous morphine administered prior to MR cholangiopancreatography can improve image quality by causing the sphincter of Oddi to contract, which increases pressure in and distention of the biliary and pancreatic ducts. Morphine administration may also be particularly helpful for the evaluation of patients with primary sclerosing cholangitis, malignant neoplasms such as cholangiocarcinoma, or cystic and non-organ-deforming benign pancreatic neoplasms.

[Study of three-dimensional reconstruction of digitized virtual hepatic images]

OBJECTIVE

To study the methods of three-dimensional reconstruction of digitized virtual hepatic.

METHODS

Images of DSCF 2511-2520 were taken from the database of digitized Virtual Chinese Human female No. 1 (VCH-F1). Method of insertion value algorithm of three-dimensional reconstruction was used to make three-dimensional block diagram. In ordering to auto-judge the position of hepatic solid and hepatic ducts, these images were shown with different colors according to the character of color and location of every spot.

RESULTS

Stereo image of hepatic solid could be shown satisfactorily. Every shape of stereo image and the structure of hepatic duct could be shown by revolving the three-dimensional image with different direction.

CONCLUSIONS

The image of hepatic database of digitized Virtual Chinese female No. 1 was exact. The three-dimensional image of the liver and hepatic duct made by insertion value algorithm of three-dimensional reconstruction were distinct, and it was a ideal method of three-dimensional reconstruction.

[Anatomic variations of the cystic duct and its junction with the common hepatic duct]

The ductus cysticus is variable in the length, position and the site where it enters the ductus hepaticus communis--the cystohepatic junction. The investigations were carried out on 100 livers (50 anatomical preparations and 50 patients) adults of both sexes, randomized trial. Main methods of the research were: anatomical macrodissection and analysis of the clinical radiograms. The ductus cysticus were present as: flat--down course in 70%, flat--horizontal course in 2%, flat--ascendant course in 4%, curved in the shape "J" in 10%, curved in the shape "S" in 12% and curved in the shape "U" in 2%. The cystohepatic junction shows variations in topographic zones.

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.

[Anatomic variants of the cystic duct and cysticohepatic junction: diagnosis with MR cholangiography]

The cystic duct are variable in length, course and site of termination. A knowledge of the variable anatomy of the cystic duct and cysticohepatic junction is important in biliary surgery, because failure to recognize anatomic variations may result in a significant ductal injury. Magnetic resonance cholangiography (MRC) is a recently developed technique that demonstrates the biliary tree noninvasively and without injection of contrast material. Anatomic variants of the cystic duct and cysticohepatic junction that may increase the risk of bile duct injury in biliary surgery are frequently identified with MRC. MRC will be a noninvasive and a useful technique in the diagnosis of anatomic variants of the cystic duct and cysticohepatic junction.

Luminal cross-sectional area and tension-strain relation of the porcine bile duct

The bile duct is a distensible tube serving to transport bile from the liver and gallbladder to the duodenum. The purpose of this study was to characterize the luminal cross-sectional area (CSA) and tension-strain properties during distension of the normal isolated porcine common bile duct in vitro. An impedance planimetric system located inside a balloon was used. Eleven porcine bile ducts were examined in two locations, in the hepatic duct and in the common bile duct. The CSAs obtained in the common bile duct were significantly higher than those in the hepatic duct in the pressure range 0-8 kPa (P < 0.001). The circumferential wall tension (T)-strain (epsilon) relations for both locations fitted to the exponential equation T = a.eb. epsilon with determination coefficients of 0.97 +/- 0.01. The a and b constants were not statistically different between the two locations indicating that the elastic properties did not differ. In conclusion, the luminal CSAs were larger in the common bile duct when compared to the hepatic duct and the tension-strain relations did not differ between the two segments of the bile duct.

The normal retrograde cholangiogram: a definition of normal caliber

PURPOSE

To evaluate normal retrograde cholangiograms to determine a normal range of ductal calibers and identify its variation with age.

MATERIALS AND METHODS

The retrograde cholangiograms of 136 patients (age range: 17-84 years; mean age 49.8 years +/- 17.3 [standard deviation]) with clinical follow-up and subsequent studies suggesting normal biliary trees were evaluated. Patients with previous cholecystectomy, choledocholithiasis, or pancreatitis were excluded. Common bile duct (CBD) and common hepatic duct (CHD) sizes were measured.

RESULTS

Measurements uncorrected for radiographic magnification of CBD revealed a mean of 8.5 mm +/- 2.7 mm [standard deviation] and CHD had a mean of 8.1 mm +/- 2.6 mm. There was an increase in CBD caliber by 0.5 mm per decade of increasing age (p < 0.001) and an increase in CHD caliber by 0.35 mm per decade of age (p < 0.01).

CONCLUSION

The range of normal cholangiographic bile duct caliber is wide and a CBD caliber of 13.9 mm occurs at the top of this range (mean plus two standard deviations). There is a small but statistically significant trend of ductal dilatation with advancing age.

Variations of the intrahepatic bile ducts: application in living related liver transplantation and splitting liver transplantation

The variations in the anatomy of intrahepatic bile ducts complicate operations in living related liver transplantation (LRLT) and therefore preoperative delineation of the biliary system is important to achieve a successful outcome. The aim of this study was to establish a standard relationship between the biliary variations and the methods of the graft splitting and anastomosis. Of 958 endoscopic retrograde cholangiographies with good visualization of bile duct branches were selected and were available for evaluation of their ramifications and variants. According to drainage of right hepatic duct and left hepatic duct, we classified the bile ducts into two major groups. Unusual routes of the intrahepatic ducts were present in 105 cases (11% in group A) the right sectoral duct drained into the left hepatic duct directly; in 200 cases (21% in groups B) the duct of segment IV drained into right side or common hepatic duct; and in 29 cases (3% in groups B) the duct of segment: II and III drained into the CBD and right hepatic duct separately. There is no specific bile duct variation that forbids someone from LRLT and SLT, but unusual intrahepatic ducts routes may require a change both in the cutting plane during graft retrieval and pattern of ductoenteral anastomosis to avoid potential complications to both donors and recipients. Cholangiography for screening intrahepatic duct variations is therefore important for safe bile drainage for both donors and recipients.

Anatomic variation of extrahepatic biliary tree structures: importance in treatment planning for radiation therapy

PURPOSE

To demonstrate the variable location of biliary tree components and to assess two treatment planning rules of thumb used for locating porta hepatic nodes for radiation therapy.

MATERIALS AND METHODS

The distance of the common hepatic duct bifurcation and duodenal papilla from adjacent vertebral bodies was measured on 34 cholangiograms, and their relationships to particular vertebral body levels were recorded. Adequacy of treatment volume to encompass porta hepatic lymph nodes was evaluated in 30 of these cholangiograms by constructing radiation portals according to the two rules of thumb.

RESULTS

Location of the common hepatic duct bifurcation and duodenal papilla varied widely. The treatment portal encompassed 13% (four of 30) of cases when the first rule of thumb was used and 80% (24 of 30) of cases when the second rule of thumb was used.

CONCLUSION

The wide variability of location of extrahepatic biliary tree structures suggests the need for individualized treatment planning so that sensitive and dose-limiting healthy tissues can be optimally excluded from radiation treatment portals. Computed tomography and other imaging modalities enable precise location of biliary tree components for radiation treatment planning.

Anatomic variants of the biliary tree: diagnosis with MR cholangiopancreatography

PURPOSE

To evaluate the accuracy of magnetic resonance (MR) cholangiopancreatography in the diagnosis of anatomic variants of the biliary tree.

MATERIALS AND METHODS

In 171 patients, the anatomy of the biliary tree was evaluated with MR cholangiopancreatography. Two independent reviewers evaluated the presence of anatomic variants. Contrast material-enhanced cholangiography that was previously performed opacified the cystic duct in 77 patients and the bile duct bifurcation in 93 patients, and was chosen as the standard of reference in the diagnosis of anatomic variants.

RESULTS

MR cholangiopancreatography demonstrated the cystic duct in 126 patients (74%). MR cholangiopancreatography showed a low cystic duct insertion in 11 patients (9%), a medical cystic duct insertion in 22 patients (17%), and a parallel course of the cystic and hepatic ducts in 31 patients (25%). The bile duct bifurcation was demonstrated in 139 patients (81%), and an aberrant right hepatic duct was demonstrated in 12 patients (9%).

CONCLUSION

MR cholangiopancreatography is accurate in the diagnosis of anatomic variants of the biliary tree that may increase the risk of bile duct injury during laparoscopic cholecystectomy.

Low insertion of hepatic segmental duct VII-VIII is an important cause of major biliary injury or misdiagnosis

BACKGROUND

The importance of variant anatomy is only mentioned generally in most articles in this era of laparoscopic cholecystectomy. We report a series of 14 patients in whom a seemingly low insertion of hepatic segmental duct VII-VIII was clinically important.

METHODS

The patients were managed at Duke University Medical Center. Two intraoperative videotapes of injury were reviewed.

RESULTS

Three categories of patients were identified: 6 patients who had injury in association with another major injury to the biliary system, 7 patients who had an isolated VII-VIII system injury, and 1 patient with a Klatskin tumor in whom the unobstructed variant duct was stented. After appropriate evaluation, all patients were successfully treated. Several lawsuits resulted, even when the injury was seemingly minor. Symptoms developed in all patients who filed lawsuits, but none in those who did not.

CONCLUSION

Appreciation of the VII-VIII biliary variant can lead to avoidance of injury or to a successful repair. The injury can easily occur despite "normal" cholangiography. Successful clinical outcome does not necessarily correlate with freedom from lawsuits.

Segmental organization of the pig liver: anatomical basis of controlled partition for experimental grafting

Segmental anatomy has been investigated on 54 pig livers by bench-top radiology and ultrasonography of hepatic and portal vessels and bile ducts and dissection of suprahepatic veins. Eight segments were recognized, homologous to those of the human liver. Major variations were found only of arterial distribution. The inferior vena cava invariably ran within the parenchyma of the right lobe and close to the liver hilum; suprahepatic veins were also entirely intraparenchymal. Therefore, the pig liver can easily be divided into two halves, but only the right one can be used for reduced-size grafting into a recipient.

[Gross morphology of the pancreas and distribution of pancreatic ducts in the rat]

Gross morphology of the pancreas and distribution of pancreatic ducts were investigated in 12 Jcl: Wistar rats. The pancreas consisted of a body and two (right and left) lobes. The pancreatic body was located along the cranial part of the duodenum. The right lobe extended into the duodenal ligament, while the left lobe extended toward the spleen into the gastrolienal ligament. In 9 animals, the number of ducts ranged between 3 and 10. Each duct joined the hepatoenteric duct. Two (right and left) large ducts found in all animals drained the right and left lobes. Other ducts observed in more than a half of the animals drained either the body or a part of the lobe.

The anatomy of the hepatoduodenal ligament in laparoscopic sonography

Laparoscopic sonography was introduced at our institution in April 1991. It is presently being tested as an alternative to peroperative cholangiography as far as the visualization of the structures of the hepatoduodenal ligament--particularly the extrahepatic bile ducts--during laparoscopic cholecystectomy are concerned. So far, 75 patients have been examined with both modalities. The structures of the hepatoduodenal ligament could be seen sonographically in all patients, while in five patients, the cholangiography had to be aborted for technical reasons. Eleven patients (15%) had anatomical variations of the bile ducts. Nine of these were diagnosed sonographically. A duodenal diverticulum and a long common channel of common bile duct and pancreatic duct were seen only on cholangiography. Variations of the hepatic arteries were found in 15 patients (20%). We conclude that intraoperative laparoscopic sonography is a reliable tool for the visualization of the structures of the hepatoduodenal ligament. This new technique might replace peroperative cholangiography in the future.

Cystic duct anatomy: an endoscopic perspective

Knowledge of the junction of the cystic and common hepatic duct is essential for endoscopic management of biliary tract disease. The cystic and common hepatic ducts were evaluated retrospectively in cholangiograms obtained for a variety of indications in 524 persons. The cysticohepatic junction was adequately visualized in 70%. Medial junctions were noted in 18% and a spiral configuration in 32%, both more common than reported. An 11% occurrence of parallel duct systems was less frequent than expected. In 10% of patients, the cystic duct entered the hepatic duct in the distal third of the extrahepatic biliary tree. The importance of understanding this anatomy is illustrated with selected cases of therapeutic biliary endoscopy and laparoscopic cholecystectomy complications. Suggestions are made for improving performance in this area.

An anatomical study of the lymphatic drainage of the gallbladder

Based upon the detailed dissections of the lymphatic system of four adult cadavers, the lymphatic drainage of the gallbladder was divided into three pathways. 1) The cholecysto-retropancreatic pathway, which can be regarded as the main pathway, had two routes, one running spirally and posteriorly from the anterior surface of the common bile duct to the right, and the other running almost straight down from the posterior surface of the common bile duct. At the retroportal segment, these routes converged at a large lymph node, which appeared critical as the main terminal lymph node of this pathway. We designated this node the principal retroportal node. 2) The cholecysto-celiac pathway was the route by which some of the lymphatics from the gallbladder ran to the left through the hepatoduodenal ligament to reach the celiac nodes. 3) The cholecysto-mesenteric pathway was the route by which some of the lymphatics ran to the left in front of the portal vein and connected with the nodes at the superior mesenteric root. These three pathways converged with the abdomino-aortic lymph nodes near the left renal vein; in particular, the nodes in the interaortico-caval space were considered important.

Biomechanical study of the bile duct system outside the liver

Diseases of the bile duct system in the digestive system after surgery are common. In order to clarify the cause of these diseases, research on the diseases from a biomechanical perspective is increasing; however, the same cannot be said of biochemical research. In this paper, by using a new, well-devised testing apparatus, specimens extracted from the bile duct system of canine body are tested. The test data are analyzed using the finite deformation theory, and mechanical properties of the bile duct system outside the liver are investigated. The conclusions show that the viscoelasticity of the bile duct system is very small. In its normal physiological condition, the bile duct wall has an almost uniform distribution of circumferential and longitudinal stress. However, when the diseases of the bile duct system cause high pressure at the bile duct, the circumferential stress and longitudinal stress at the bile inside wall suddenly increase and are much larger than those stresses at the outside wall. The elastic modulus gradually becomes small from the common bile duct and the common hepatic duct to hepatic duct, and the value of elastic modulus for the cystic duct is almost equal to that of the hepatic duct.

[Clinical significance of the relation of primary or secondary hepatic ducts and their surrounding vessels]

It is necessary that surgeons, who perform the operation on the primary and secondary hepatic ducts, should be familiar with the topography of these ducts and their surrounding vessels. A total of 22 "frame-specimens" of cadaveric liver (FSL) were built by the authors, from which the length of left and right hepatic ducts (LHD, RHD), right anterior lobe duct (RAD), the distance from the confluence of RAD and right posterior lobe duct (CAP) to the visceral surface of the liver, and the projection point of CAP on the diaphragmatic surface of Liver were all directly measured. The relationship between these proximal hepatic ducts and their surrounding vessels was also observed. Based on this study the authors proposed a new approach to incision of the whole length of LHD, RHD and RAD. The stenotic opening of right posterior lobe duct (RPD) can be exposed through the lumen of RHD. In 18.2% of 22 FSLs, the right posterior lobe artery was found in the lateral angle formed by RAD and RPD. To prevent the damage of this artery, which may cause intrahepatic hematoma, and its rupture into biliary tract, the cholongiotomy incision at the stenotic opening of RPD should be made within the lateral-superior quadrant of it close to the horizontal level.

[Standardized sonographic measurement of the width of the extrahepatic bile ducts]

As there are no exact data available which part of the bile duct should be measured, the hepatoduodenal ligament was examined in 20 cadavers. The constant anatomic relationship between the right hepatic artery and the common hepatic duct is shown. A right hepatic artery properly originating from the hepatic artery passes to 85% dorsally and to 15% ventrally of the common hepatic duct, but remains ventrally to the portal vein. If the right hepatic artery is shown dorsal to the portal vein (20%), an accessory right hepatic artery should be suggested. To maintain uniformity of measurement, the size of the common hepatic duct should be recorded immediately caudal to the right hepatic artery.

Bioconstruction of the extrahepatic biliary duct system in minipigs. Comparing normal condition with experimental obstruction

The extrahepatic biliary duct system is subject to a particular bioconstruction to secure its bile transport function. The dominant structure of the bile duct wall is a network of collagen fibres harboring muscle-fibre bundles. The collagen fibres are virtually inelastic, volumes can be changed only by rearranging the network. The ducts show different spatial arrangements of the fibres causing different extents of dilatation during obstruction. Extreme dilatation might cause a rupture of the network, and deficient postoperative retonisation could be the result.

Glandular elements around the intrahepatic bile ducts in man; their morphology and distribution in normal livers

The morphology and distribution of the glandular elements around the intrahepatic bile ducts, hitherto poorly described, were examined in autopsied human livers with the aid of postmortem cholangiographs. The glands could be divided into intramural and extramural. The former were small in number, scattered within the bile duct walls, and were simple tubular mucous glands. The latter were more abundant, located in the periductal connective tissue, and were branched tubuloalveolar seromucous glands. Serial section observations revealed that neither gland communicated with the hepatic parenchyma, and the extramural glands drained into the large bile duct lumina via the conduits. The mucous cells of both glands contained neutral, carboxylated and sulfated glycoproteins. The extramural glands were distributed from the hepatic to the segment ducts in almost all livers, and were also discerned around the area ducts in two-fifths of the livers. The glands seemed to decrease in number as the bile ducts became more branched.

The need for careful operative dissection in Moosman's area during cholecystectomy

Anatomy contributes two operative difficulties to the surgeon during cholecystectomy; one is access or exposure, and second is variation. Eighty-five per cent of all variations in the hepatic pedicle are found within Moosman's area which is an area the size of a fifty cent coin in the cystohepatic duct angle. Fifty per cent of the variation within Moosman's area is a potential hazard during cholecystectomy. Vessels passing ventrally are most important because bile ducts may be injured in efforts to stop hemorrhage from these vessels. Moosman's (25) area is indeed the zone of careful operative procedure in cholecystectomy.

Morphometrical evaluation of extrahepatic bile ducts in reference to their structural changes with aging

Forty-three autopsy cases with neither history nor anatomic evidence of hepatobiliary or pancreatic diseases were submitted to morphometrical evaluation of the internal diameter of the common hepatic duct. At a cross section of the duct the perimeter length of the mucosal basement membrane was measured to calculate its diameter D to be obtained when it was stretched into a circle. The value of D was found to correlate significantly with age, with the upper rejection limit (5% level) increasingly elevated from 4.8 mm at 20 years to 7.5 mm at 80 years. This implies that the age of patient should be taken into account in judging clinically whether or not bile ducts actually are dilated. The density in the ductal wall of elastic fibers was also determined and was shown to increase as the senile dilatation progressed, a sign of adaptive reinforcement of wall tissue that is liable to gradual hysteresis under chronic tension load.

An anatomic investigation of radical resection of tumor in the hepatic duct confluence

The fetal umbilical vein in the ligamentum teres can be reopened to provide a 10 centimeter long vein, as wide as the left portal vein or the central splenic vein, that gives access to the left portal vein in the umbilical fissure of the liver. By cutting the ligamentum teres, this potential autologous venous graft is lost and, therefore, the ligamentum teres should never be sacrificed without reason. The umbilical side of the reopened umbilical vein can be anastomosed with the splenic vein to form a portal vein bypassing conduit that enters the liver in the umbilical fissure and take over function of the portal vein. From the results of this postmortem investigation, it can be concluded that radical block resection of the area consisting of the hepatic duct confluence, classic right hepatic lobe and complete hepatoduodenal ligament, preceded by construction of a complete separate afferent blood supply of the classic left hepatic lobe, is possible both anatomically and technically. There is no indication denying the supposition that the result of such a procedure is functionally analogous to standard extended right lobectomy with bilioenteric reconstruction.

Sonographic evaluation of bile duct size during pregnancy

Real-time sonography was used to examine the biliary tracts of 103 pregnant women. Common hepatic duct size, degree of right hydronephrosis, and presence of gallstones were noted. There were three important observations: (1) The top normal size of the common hepatic duct was 5 mm; (2) no correlation was found between common hepatic duct size and stage of pregnancy or degree of right hydronephrosis; and (3) gallstones were incidentally noted in 3.9% of patients.

Radiological anatomy of the bile ducts based on intraoperative investigation in 250 cases

Intraoperative cholangiograms were studied in 250 patients. Analysis of the data obtained led to the establishment of a protocol for intraoperative cholangiography aimed at identification of anatomical anomalies and variations. Diagnosis of the latter must be achieved in order to avoid possible intraoperative complications. The common hepatic duct was formed by the junction of the right and left hepatic ducts in 52% of the cases studied. Absence of convergence of the posterior and anterior rami of the right hepatic duct was found in 30% of cases. Anatomical variations of the right sectorial duct system were seen in 12% of cases. Conversely, variations of the left sectorial duct system were rarely seen (2% of cases). Careful examination of the intraoperative cholangiograms led us to suspect certain anatomical variations in close to 1% of cases. These variations included abnormal hepatocystic duct, which if undiagnosed could lead to choleperitoneum or inadvertent ligation of the right hepatic duct. An abnormal hepatocystic duct terminating on the gall bladder was found in one patient. Study of the origin of the common bile duct allowed us to define the mode of termination of the cystic duct (on the right margin of the common hepatic duct in 80% of cases) and to identify a short choledochus in 2% of cases. Finally, variations of the duodenal termination of the common bile duct were studied and reflux into the pancreatic duct was seen in 27% of cases. However, the pathological significance of such reflux was rarely found.

Age and sex dependency of bile duct diameter and bile duct pressure--an ERC manometry study

Using ERC-manometry diameters of the common bile duct (CBD) the common hepatic duct (CHD) as well as CBD pressure before and after opacification were determined in 35 non-cholecystectomized patients without extrahepatic cholestasis. We found a significant rise of both CBD and CHD diameters as well as CBD pressure recorded before the injection of contrast medium with increasing age. (p less than 0.005, less than 0.001 and less than 0.05 respectively). Following the opacification CBD pressure became elevated. Again this increase tended to be more pronounced in older patients although this association was lacking statistical significance. In the presence of comparable age female patients (n = 16) exhibited higher CBD and CHD diameters (n.s.) as well as CBD pressure values (p less than 0.05) than male patients (n = 19). We conclude that in the absence of extrahepatic cholestasis bile duct diameter as well as bile duct pressure rise significantly with increasing age. Furthermore women tend to have higher diameters and pressure values than men.

Effect of examination time of day on the quality of real-time cholesonograms

Real-time sector scans of the gallbladder and common hepatic duct were performed at 7:00 a.m., 1:00 p.m., and 5:00 p.m. on 16 volunteers eating a regular diet. Technically satisfactory but not ideal scans of the common duct could be obtained irrespective of dietary status or time of day. As the day progressed, about one-half of subjects having gallbladder scans showed a significant decrease in bile volume, spurious gallbladder wall thickening, or compromised images from excessive intestinal gas. The data suggest that, if possible, gallbladder imaging should be performed early in the morning after overnight fasting, even when high-resolution sector scanners are used. However, because nearly one-half of patients can have satisfactory scans under any circumstances, cholesonograms should be performed in emergency situations or in those instances where patients would suffer inconvenience or financial hardship by delay of the study for an additional day.

[Parallel and spiral anomalies of the cystic duct]

Parallel and spiral anomalies of the cystic duct, that are found in every fourth--fifth patient, are of certain importance for the practical surgery. When at cholecystectomy a hidden long stump of the anomalous cystic duct is left it might result in the same complications which are described when a long external stump of the cystic duct is left. Analysing anatomical peculiarities and positions of the anomalous cystic ducts as regards to the common hepatic duct, found in 51 patients at operations, it was revealed: the length of the anomalous course of the cystic duct in 13 patients was 20-25 mm, in 30 patients--from 30 up to 50 mm, in 10 patients--60--75 mm. The parallel anomalies were revealed in 18 patients, the spiral ones--in 23 patients. In the latter cases the cystic duct adjoined the anterior, posterior and even the medial walls of the common hepatic duct and had not only an oblique-spiral course, but a transversal one, too. For these 6 variants certain working terms were suggested. In 10 patients mixed anomalies of the cystic ducts were found with its parallel and spiral disposition. Four types of the mixed anomalies were distinguished and they were also given certain working terms. The terms suggested for the variants of the cystic ducts could be helpful for medical documentation and for exact statistics of these anomalies.

Sonography of the normal pediatric gallbladder and biliary tract

Fifty-one pediatric patients (range, 1 mo. to 16 yr.), all of whom had normal clinical findings and laboratory data pertaining to the gallbladder and biliary tract, were examined by ultrasound. Scans showed a gradual increase in the size of the gallbladder with age; only one patient had a gallbladder diameter greater than 3.5 cm or a length greater than 7.5 cm. Wall thickness could be measured in 45 patients and was never more than 3 mm. The lumen of the common hepatic duct gradually increased with age but was never greater than 4 mm. The right portal vein also showed a gradual increase with age.

Porta hepatis: sonographic discrimination of bile ducts from arteries with pulsed Doppler with new anatomic criteria

Duplex scanning of the porta hepatis was performed in 71 patients, and the identity of the common duct and hepatic artery were confirmed by characteristic pulsed Doppler signals or by tracing structures to known landmarks. In 59% of patients, the hepatic artery was as large or larger than the adjacent normal bile duct, suggesting that the two structures may occasionally be confused. Sonographic signs that help to confirm or support the differentiation of arteries from ducts include observation of intrinsic pulsations of arteries, indentation or displacement of structures by arteries, change in the caliber of bile ducts during real-time examination, and the orientation, contour, caliber, and curvature of the tubular structures of the porta hepatis. Simultaneous identification of the hepatic artery and extrahepatic bile duct using pulsed Doppler or these newly described anatomic criteria improves the diagnostic accuracy of sonography of the porta hepatis.