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To improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese Society of Hepato-Biliary-Pancreatic Surgery. The aim of the study was to evaluate transition in the characteristics and treatment strategy in CRLM patients and analyze prognostic factors using large-scale data. The present study summarizes the data of patients newly diagnosed between 2015 and 2017 and presents prognostic data of patients newly diagnosed in 2013 and 2014. Survival curves were generated by the Kaplan-Meier method and compared by log-rank test. Multivariate analyses were carried out using Cox proportional hazard modeling. The data of 4502 patients newly diagnosed with CRLM between 2015 and 2017 and the prognostic data of 2427 patients diagnosed in 2013 and 2014 are included. Regarding the 2013 and 2014 prognostic data, the 5-year overall survival (OS) rates of patients who underwent hepatectomy alone was 59.8%. Multivariate analyses identified age at diagnosis of CRLM ≥70 years, concomitant extrahepatic metastasis at diagnosis of CRLM, tumor depth of primary lesion ≥subserosa/pericolic or perirectal tissue, mutant KRAS status, number of CRLM ≥5, maximum diameter of CRLM5 cm, and surgical curability R1/R2 as independent predictors of OS. Analysis of the latest nationwide database of patients diagnosed with CRLM revealed changes in patients and oncological characteristics, a transition in treatment strategy, and different independent prognosticators to those reported previously.

Although the number of minimally invasive liver resections (MILRs) has been steadily increasing in many institutions, minimally invasive anatomic liver resection (MIALR) remains a complicated procedure that has not been standardized. We present the results of a survey among expert liver surgeons as a benchmark for standardizing MIALR.We administered this survey to 34 expert liver surgeons who routinely perform MIALR. The survey contained questions on personal experience with liver resection, inflow/outflow control methods, and identification techniques of intersegmental/sectional planes (IPs).All 34 participants completed the survey; 24 experts (70%) had more than 11 years of experience with MILR, and over 80% of experts had performed over 100 open resections and MILRs each. Regarding the methods used for laparoscopic or robotic anatomic resection, the Glissonean approach (GA) was a more frequent procedure than the hilar approach (HA). Although hepatic veins were considered essential landmarks, the exposure methods varied. The top three techniques that the experts recommended for identifying IPs were creating a demarcation line, indocyanine green negative staining method, and intraoperative ultrasound.Minimally invasive anatomic liver resection remains a challenging procedure; however, a certain degree of consensus exists among expert liver surgeons.

Background Although we previously proposed a nomogram to predict malignancy in intraductal papillary mucinous neoplasms (IPMN) and validated it in an external cohort, its application is challenging without data on tumor markers. Moreover, existing nomograms have not been compared. This study aimed to develop a nomogram based on radiologic findings and to compare its performance with previously proposed American and Korean/Japanese nomograms. Methods We recruited 3708 patients who underwent surgical resection at 31 tertiary institutions in eight countries, and patients with main pancreatic duct > 10 mm were excluded. To construct the nomogram, 2606 patients were randomly allocated 1:1 into training and internal validation sets, and area under the receiver operating characteristics curve (AUC) was calculated using 10-fold cross validation by exhaustive search. This nomogram was then validated and compared to the American and Korean/Japanese nomograms using 1102 patients. Results Among the 2606 patients, 90 had main-duct type, 900 had branch-duct type, and 1616 had mixed-type IPMN. Pathologic results revealed 1628 low-grade dysplasia, 476 high-grade dysplasia, and 502 invasive carcinoma. Location, cyst size, duct dilatation, and mural nodule were selected to construct the nomogram. AUC of this nomogram was higher than the American nomogram (0.691 vs. 0.664, p = 0.014) and comparable with the Korean/Japanese nomogram (0.659 vs 0.653, p = 0.255). Conclusions A novel nomogram based on radiologic findings of IPMN is competitive for predicting risk of malignancy. This nomogram would be clinically helpful in circumstances where tumor markers are not available. The nomogram is freely available at http://statgen.snu.ac.kr/software/nomogramIPMN.

Purpose In this systematic review, we aimed to clarify the useful anatomic structures and assess available surgical techniques and strategies required to safely perform minimally invasive anatomic liver resection (MIALR), with a particular focus on the hepatic veins (HVs). Methods A systematic review was conducted using MEDLINE/PubMed for English articles and Ichushi databases for Japanese articles through September 2020. The quality assessment of the articles was performed in accordance with the Scottish Intercollegiate Guidelines Network (SIGN). Results A total of 3,372 studies were obtained, and 59 were selected and reviewed. Due to the limited number of published comparative studies and case series, the degree of evidence from our review was low. Thirty-two articles examined the anatomic landmarks and crucial structures for approaching HVs. Regarding the direction of HV exposure, 32 articles focused on the techniques and advantages of exposing HVs from either the root or the periphery. Ten articles focused on the techniques to perform a segmentectomy 8 in particularly difficult cases of MIALR. In seven articles, bleeding control from HVs was also discussed. Conclusions This review may help experts reach a consensus regarding the best approach to the management of hepatic veins during MIALR.

Background Minimally invasive pancreaticoduodenectomy (MIPD) has recently been safely performed by experts, and various methods for resection have been reported. This review summarizes the literature describing surgical approaches for MIPD. Methods A systematic literature search of PubMed (MEDLINE) was conducted for studies reporting robotic and laparoscopic pancreaticoduodenectomy; the reference lists of review articles were searched. Of 444 articles yielded, 23 manuscripts describing the surgical approach to dissect around the superior mesenteric artery (SMA), including hand-searched articles, were assessed. Results Various approaches to dissect around the SMA have been reported. These approaches were categorized according to the direction toward the SMA when initiating dissection around the SMA: anterior approach (two articles), posterior approach (four articles), right approach (16 articles), and left approach (three articles). Thus, many reports used the right approach. Most articles provided a technical description. Some articles showed the advantage of their method in a comparison study. However, these were single-center retrospective studies with a small sample size. Conclusions Various approaches for MIPD have been reported; however, few authors have reported the advantage of their methods compared to other methods. Further discussion is needed to clarify the appropriate surgical approach to the SMA during MIPD.

Background A large amount of blood flows in and out of the liver through the inflow system consisting of the portal vein and hepatic artery within the Glissonean cord and the outflow system constituted by the hepatic veins. Methods During liver parenchymal dissection, useful methods to maintain a dry operative field are to control the inflow system with the Pringle maneuver and the outflow system by managing the central venous pressure. Additionally, mature techniques of dissecting the liver parenchyma, which can prevent injury to the blood vessels and appropriately and promptly stop bleeding, are fundamental. Similar to archaeological excavation, in which buried remains are unearthed and exposed in intact form, the Glissonean cords and hepatic veins buried in the liver parenchyma should be exposed or isolated without causing injury to these structures during liver parenchymal dissection. Results The cavitron ultrasonic surgical aspirator (CUSA) is useful as a surgical device for excavation because it has multiple functions in one device. However, there have been no systematic guidelines on how to use it effectively during hepatectomy. Conclusion We herein describe how to use the CUSA, based on our knowledge and experiences.

Highlight Although recent advances in robotic surgery have enabled more precise movements of the needle driver, a sophisticated laparoscopic suturing technique is still desired. Honda and colleagues describe the basic knowledge of and a small but useful trick for atraumatic needle driving in laparoscopic suturing, based on mechanistic considerations.

To collect large-scale data for further research to improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese society of Hepato-Biliary-Pancreatic Surgery. The joint committee was initiated to collect data since 2014 and has already reported data including the prognostic data of 3820 patients newly diagnosed with CRLM between 2005 and 2007.The data of patients newly diagnosed with CRLM after 2013 are continuously being registered prospectively, and herein, we report the data of the patients newly diagnosed with CRLM in 2013 and 2014.The data of 3839 patients newly diagnosed with CRLM in 2013 and 2014 were registered from 156 departments (75%) of 152 institutions among 209 departments (from 201 institutions) that agreed to participate in this database system at its initiation. Finally, 3525 patients were enrolled in this study after a quality management process conducted by the joint committee. We report the comprehensive data obtained from 3525 patients, including clinicopathological findings, treatment strategies, and implementation status of chemotherapy.The joint committee will provide these raw data while updating prognostic data to researchers who will conduct meaningful studies that meet the aim of the joint committee.

Laparoscopic pancreaticoduodenectomy (LPD) requires sufficient laparoscopic training for optimal outcomes. Our aim is to determine the learning curve and investigate the factors influencing surgical outcomes during the learning curve.We analyzed surgical results of 150 consecutive cases of LPD performed by three hepatopancreatobiliary surgeons during their 50 first cases. Learning curves were constructed by cumulative sum (CUSUM) analysis. Preoperative factors influencing resection time and blood loss were investigated in the introductory and stable periods. RESULTS : The learning curve could be divided into three phases: initial (1-20 cases), plateau (21-30), and stable (31-50). Resection time with lymph node dissection was significantly longer during the introductory period (initial and plateau periods) (P0.01) but not the stable phase (P = 0.51). Multivariate analysis revealed that patients with pancreatitis had longer resection times and massive blood loss in both the introductory and stable periods (stable phase). High visceral fat area was also significantly related to massive blood loss in the introductory period (P = 0.04).Hepatopancreatobiliary surgeons need more than 30 cases until LPD becomes stable. Lymph node dissection and patients with high visceral fat area and concomitant pancreatitis should be avoided during the introductory period of the learning curve.

To collect big data for further research to improve treatment outcomes in patients with colorectal liver metastasis (CRLM), the Joint Committee for Nationwide Survey on CRLM was established by the Japanese Society for Cancer of the Colon and Rectum and the Japanese Society of Hepato-Biliary-Pancreatic Surgery. The joint committee initiated data collection since 2014. The data of 4,237 patients newly diagnosed with CRLM between 2005 and 2007 were registered from 134 departments of 127 institutions (64%) among 209 departments (from 201 institutions) that agreed to participate in this study. Finally, 3,820 patients were enrolled in this report after a quality management process by the joint committee. We report the comprehensive data obtained from 3,820 patients, clinicopathological findings, treatment strategies, prognoses, and implementation status of chemotherapy. The joint committee is prospectively collecting data of patients newly diagnosed with CRLM after 2013 and will provide these raw data, including data of patients diagnosed between 2005 and 2007, to researchers who will conduct meaningful studies that meet the aim of the joint committee.

Introduction We employed a safe approach during laparoscopic splenectomy by first mobilizing the pancreatic tail and then dissecting the splenic vessels at the splenic hilum before mobilizing the spleen. Materials and Surgical Technique Patients were placed in the lithotomy position, and only the upper body was twisted to the right side. Five trocars were placed. After the bursa omentalis was opened, an avascular layer was identified behind the pancreas. This avascular layer was bluntly dissected, and the pancreatic tail was isolated from the retroperitoneum. The tissue surrounding the splenic hilum was dissected by a handling tape that was placed around the pancreatic tail. Because the spleen remained connected to the retroperitoneum with the splenorenal ligament, a good operative view of the splenic hilum was obtained with proper extension. After sufficient space was secured between the pancreatic tail and the spleen, the splenic vessels were divided with a linear stapler. The spleen was detached in the final stage. Discussion The current standardized procedure is highly recommended for a safe laparoscopic splenectomy.

Background Generally, surgeons’ perceptions of surgical safety are based on experience and institutional policy. Our recent pilot survey demonstrated that the acceptable duration of surgery and criteria for open conversion during laparoscopic cholecystectomy (LC) vary among workplaces. Methods A web-based survey was distributed to 554 expert LC surgeons in Japan, Korea, and Taiwan. The questionnaire covered LC experience, safety measures and recognition of landmarks, decision-making regarding conversion to open/partial cholecystectomy and the implications of this decision. Overall responses were compared among nations, and then stratified by LC experience level (lifetime cases 200–499, 500–999, and ≥1000). Results The response rate was 92.6% (513/554); 67 surgeons with ≤199 LCs were excluded, and responses from 446 surgeons were analyzed. We observed significant differences among nations on almost all questions. Differences that remained after stratification by LC experience were on questions related to acceptable duration of surgery, adoption rates of intraoperative cholangiography, the “critical view of safety” technique, identification of Rouviere's sulcus, recognition of the SS-Inner layer theory, and intraoperative judgment to abandon conventional LC. Conclusions Even among experts, surgeons’ perceptions during LC are workplace-dependent. A novel grading system of surgical difficulty and standardized LC procedures are paramount to generate high-level evidence. This article is protected by copyright. All rights reserved.

Background Prospective studies are needed to understand the safety and feasibility of laparoscopic pancreatectomy. The aim of the present study was to describe laparoscopic pancreatectomy currently undertaken in Japan, using a prospective registration system. Methods Patient characteristics and planned operations were registered preoperatively, and then the performed operation and outcomes were reported using an online system. Collected data were also compared between institutions based on their level of experience. This study was registered with UMIN000022836. Results Available data were obtained from 1,429 patients at 100 Japanese institutions, including 1,197 laparoscopic distal pancreatectomies (LDPs) and 232 laparoscopic pancreatoduodenectomies (LPDs). The rates of completion for planned operations were 92% for LDP and 91% for LPD. Postoperative complication rates after LDP and LPD were 17% and 30%, and 90-day mortality rates were 0.3% and 0.4%, respectively. Shorter operation time, less blood loss, and lower incidence of pancreatic fistula were observed in institutions experienced in LDP. A higher rate of pure laparoscopic procedure and shorter operation time were noted in institutions experienced with LPD. Conclusion LDPs and LPDs are performed safely in Japan, especially in experienced institutions. Our data could support the next challenges in the field of laparoscopic pancreatectomy.

Background/Purpose Serious complications continue to occur in laparoscopic cholecystectomy (LC). The commonly used indicators of surgical difficulty such as the duration of surgery are insufficient because they are surgeon and institution dependent. We aimed to identify appropriate indicators of surgical difficulty during LC. Methods A total of 26 Japanese expert LC surgeons discussed using the nominal group technique (NGT) to generate a list of intraoperative findings that contribute to surgical difficulty. Thereafter, a survey was circulated to 61 experts in Japan, Korea, and Taiwan. The questionnaire addressed LC experience, surgical strategy, and perceptions of 30 intraoperative findings listed by the NGT. Results The response rate of the survey was 100%. There was a statistically significant difference among nations regarding the duration of surgery and adoption rate of safety measures and recognition of landmarks. The criteria for conversion to an open or subtotal cholecystectomy were at the discretion of each surgeon. In contrast, perceptions of the impact of 30 intraoperative findings on surgical difficulty (categorized by factors related to inflammation and additional findings of the gallbladder and other intra-abdominal factors) were consistent among surgeons. Conclusions Intraoperative findings are objective and considered to be appropriate indicators of surgical difficulty during LC.

Background Among young residents, there seems to be a decreasing desire to become surgeons, resulting in a decrease in the number of surgeons. There is concern regarding a shortage of hepatobiliary pancreatic (HBP) surgery residents in Japan. A questionnaire survey was designed to assess the work motivations of Japanese gastrointestinal (GI) and HBP surgeons. Methods Questionnaires assessing seven domains related to motivation (aptitude, satisfaction/dissatisfaction, knowledge/skill, evaluation/approval, self-management, community/expectation from other parties, and emotion) were sent to GI and HBP surgeons throughout Japan. Differences between HBP and GI surgeons were analyzed. Results Responses were received from 27 institutions in Japan between May and August 2014. Mid-career and senior HBP surgeons (11–20 years after graduation) working in university hospitals were significantly less satisfied with their work than GI surgeons (P = 0.036). Evaluation/approval factors were significantly lower in senior HBP surgeons than in GI surgeons 16–20 years after graduation (P = 0.048). Conclusions The future satisfaction of young residents seeking to become HBP surgeons should be enhanced, providing an appealing workplace for young residents and preventing discontinuation by mid-career and senior surgeons.

An incorrect approach to the critical view of safety can cause bile duct and/or vascular injury. However, only superficial anatomical features have been proposed as surgical landmarks to initiate laparoscopic cholecystectomy (LC) safely in previous reports. Accordingly, we have proposed a novel surgical anatomical definition of the gallbladder wall, in which the subserosal (SS) layer is divided into the inner layer of the SS (SS-Inner) layer consisting of vasculature and fibrous tissue, and the outer layer of the SS (SS-Outer) layer consisting of abundant fat tissue. By dissecting the gallbladder along the SS-Inner layer after exposure at a safe region, bile duct and/or vascular injury can be avoided, even in cholecystitis cases. Furthermore, recognition of this surgical anatomy reveals several aspects. In cholecystitis cases associated with severe fibrotic change, completion of LC by dissecting along the SS-Inner layer is impossible, resulting in abandonment of regular LC. An abscess in the liver bed associated with acute cholecystitis usually forms in the SS-Outer layer, thus, the gallbladder can be dissected easily. In the dome-down technique, the right hepatic duct is endangered by whole-layer dissection, in which the SS-Outer layer is also removed. The proposed procedure should become the universal standard for LC.

Background The optimal therapeutic strategy for very elderly pancreatic cancer patients remains to be determined. The aim of this study was to clarify the role of pancreatic resection in patients 80 years of age or older. Methods A retrospective multicenter analysis of 1401 patients who had undergone pancreatic resection for pancreatic cancer was performed. The patients aged ≥80 years (n = 99) were compared with a control group

Background The aim of the present study was to clarify the surgical outcome and long-term prognosis of laparoscopic liver resection (LLR) compared with conventional open liver resection (OLR) in patients with colorectal liver metastases (CRLM). Methods A one-to-two propensity score matching (PSM) analysis was applied. Covariates (P

Background An aberrant right posterior sectoral hepatic duct (PHD) draining into extrahepatic bile duct, gallbladder or cystic duct directly is a common and critical anomaly during cholecystectomy. This study aimed to investigate the frequency of aberrant PHD and describe why PHD is critical. Methods In 753 consecutive patients who underwent laparoscopic cholecystectomy (LC) using our standardized procedure over 9 years, we reinvestigated whether an aberrant PHD was present using preoperative images. A PHD joining the common bile duct through the cranial side of the hilar plate was defined as the supraportal type, and one passing through the caudal side of the right portal vein was defined as the infraportal type. Results Fifty-one (6.8%) patients had aberrant PHD. All of them had the infraportal type, and the cystic duct drained into aberrant PHD in 10 (1.3%) and aberrant PHD drained into the cystic duct in six (0.8%). These 16 most dangerous anomalies were diagnosed before surgery. In all patients with aberrant PHD, LC was completed without any complications. Conclusions It seems possible to identify most aberrant PHD by attention to the infraportal-type PHD, and injury to them can be avoided by exposing a critical view using an appropriate procedure.

Background The optimal cut-off value of the number of colorectal liver metastases (CRLM) to predict prognosis after hepatic resection remains unclear. This study was conducted to determine a suitable cut-off value. Methods A total of 727 hepatectomized patients with CRLM were evaluated. We proposed the following optimal cut-off values: first, a small P-value for the log-rank test with no overlapping of the 95% confidence interval (CI) for median survival time using the Kaplan–Meier method and the hazard ratio (HR) using the Cox proportional hazards model and, second, the maximum HR value for accurate separation. Results For disease-free survival analysis, of the three group separations, A2 (1, 2–4, and ≥5) showed a small P-value and the largest HR, whereas two group separations, B2, B3 and B4 showed similarly small P-values, but B4 (1–4, ≥5) indicated the largest HR. Regarding the overall survival analysis, of the three group separations, A2 showed the smallest P-value, whereas the two group separations, B4 showed similarly small P-values, with the largest HR. Conclusions Tumor number separation in patients with CRLM after hepatic resection should be performed using the A2 (1, 2–4, and ≥5) or B4 (1–4 and ≥5) classifications.

Background Little is known about the effects of neoadjuvant therapy on outcomes in patients with pancreatic cancer. This study evaluated the effects of neoadjuvant therapy on resectability and perioperative outcomes. Methods A total of 992 patients were enrolled, with 971 deemed eligible. Of these, 582 had resectable tumors and 389 had borderline resectable tumors, and 388 patients received neoadjuvant therapy. Demographic characteristics and peri- and postoperative parameters were assessed by a questionnaire survey. Results The R0 rate was significantly higher in patients with resectable tumors who received neoadjuvant therapy than in those who underwent surgery first, but no significant difference was noted in patients with borderline resectable tumors. Operation time was significantly longer and blood loss was significantly greater in patients who received neoadjuvant therapy than in those who underwent surgery first, but there were no significant differences in specific complications and mortality rates. The node positivity rate was significantly lower in the neoadjuvant than in the surgery-first group, indicating that the former had significantly lower stage tumors. Conclusions Neoadjuvant therapy may not increase the mortality and morbidity rate and may be able to increase the chance for curative resection against resectable tumor.

Even during laparoscopic hepatectomy, a technique is often required to expose the major vessels, for example, in anatomical hepatectomy. We have standardized and performed such laparoscopic hepatectomy as successfully as open hepatectomy. We divide the liver parenchyma without pre-coagulation, exposing the major vessels using CUSA. To control the bleeding, we keep the central venous pressure low and often perform Pringle’s maneuver. Over 49 months, we performed totally laparoscopic hepatectomies in 41 patients with the technique of exposing the major vessels. These included major hepatectomy in 7, sectorectomy in 17, segmentectomy in 14, and others in 3. The median operative time was 361 (range 176–605) minutes, with median blood loss of 216 (range 0–1600) g. The conversion rate was 4.9 %. Postoperative morbidity rate was 9.8 % (prolonged ascites in 1, port site infection in 1, peroneal palsy in 2). Mortality was zero. The median length of hospital stay after surgery was 8 (range 5–28) days. No local recurrence was found at the time of writing. By using our standardized procedure exposing the major vessels, we could raise the quality of laparoscopic hepatectomy toward the level of open hepatectomy significantly.

Introduction: While the amount of blood loss during laparoscopic hepatectomy tends to be smaller than that during open hepatectomy, intermittent vascular occlusion to control hepatic inflow can diminish blood loss during laparoscopic hepatectomy. Described herein is a useful and convenient method for intermittent vascular occlusion, which was standardized for laparoscopic hepatectomy. Methods: A tourniquet system consisting of cloth tape and a 20-cm catheter was used for intermittent vascular occlusion. This was placed through a hole in the abdominal wall from which a 5-mm trocar had been extracted. By operating this tourniquet system outside the patient’s body, we were easily able to repeat intermittent vascular occlusion. Twenty-three patients underwent laparoscopic hepatectomy using this system. Results: The mean time of operation and vascular occlusion were 311.6 and 83.6 min, respectively. The mean blood loss was 215.0 mL. There were no intraoperative blood transfusions or critical postoperative complications. The average length of postoperative hospital stay was 6.5 days. The mean time to place this system was 354 s, and there were no complications caused by this system.

The aim of this study was to create a nomogram to predict the disease-free survival of patients with colorectal liver metastases treated with hepatic resection.Perioperative factors were assessed in 727 hepatectomized patients with colorectal liver metastases between 2000 and 2004 at the 11 institutions of the "Project Committee of the Liver" in the Japanese Society of Hepato-Biliary-Pancreatic Surgery. A nomogram was developed as a graphical representation of a stepwise Cox proportional hazards regression model.Perioperative mortality was 0.55%. Disease-free and overall survival rates were 31.2 and 63.8% at 3 years, 27.2 and 47.7% at 5 years, and 24.7 and 38.5% at 10 years, respectively. Six preoperative factors were selected to create the nomogram for disease-free survival: synchronous metastases, 3 points; primary lymph node positive, 3 points; number of tumors 2-4, 4 points and ≥5, 9 points; largest tumor diameter5 cm, 2 points; extrahepatic metastasis at hepatectomy, 4 points, and preoperative carbohydrate antigen 19-9 level100, 4 points. The estimated median disease-free survival time was easily calculated by the nomogram:8.4 years for patients with 0 points, 1.9 years for 5 points, 1.0 years for 10 points, and the rates were lower than 0.6 years for patients with more than 10 points.This nomogram can easily calculate the median and yearly disease-free survival rates from only 6 preoperative variables. This is a very useful tool to determine the likelihood of early recurrence and the necessity for perioperative chemotherapy in patients with colorectal liver metastases after hepatic resection.

Introduction: During laparoscopic cholecystectomy, an enlarged field of vision increases safety and precision, but surgeons often encounter bleeding that can cause difficulties. It is important to prevent and control arterial bleeding from Calot's triangle and the liver bed that results from injury to the deep branch of the cystic artery (DBCA). However, no previous reports have mentioned the layer between the gallbladder and liver through which the DBCA runs. Materials and Surgical Technique: To determine this layer, we investigated the histological findings from consecutive thin-slice (3 mm) blocks in six cases (three cadavers and three patients who underwent extended cholecystectomy). Results: The subserosal layer of the gallbladder wall can be divided into an inner (ss-i) layer, which consists of abundant vasculature and some fibrous tissue, and an outer (ss-o) layer, which consists of abundant fat tissue. DBCA runs through the ss-o layer, far from the ss-i layer in Calot's triangle, and runs toward the gallbladder body and ramifies into several branches that flow into the ss-i layer. Discussion: If the gallbladder is dissected in the layer close to the ss-i layer, as in our standardized procedure, the subbranches of DBCA are transected at the border of the ss-i layer, and most of the DBCA is left within the ss-o layer in Calot's triangle and the liver bed. Knowledge of the anatomy of DBCA is useful to avoid and stop bleeding from the deep part of Calot's triangle and the liver bed.

Gallbladder cancer occurs frequently in patients with pancreaticobiliary maljunction due to pancreatobiliary reflux. Pancreatobiliary reflux is also detected in some patients with a relatively long common channel. This study aimed to clarify the correlation between pancreatobiliary reflux and the length of a common channel.Two hundred and three patients, in whom both the length of a common channel and amylase level in the bile were measured, were enrolled from nine centers.Bile amylase level was correlated with the length of a common channel (P0.01). The minimum length of a common channel that could induce a markedly elevated amylase level in the bile (1,000 mg/dl) was determined as 5 mm. We redefined high confluence of pancreatobiliary ducts (HCPBD) as cases with a common channelor = 5 mm, in which the communication between the pancreatic and bile ducts was occluded with the sphincter contraction. Gallbladder cancer was found in 20% of 56 redefined HCPBD patients. Bile amylase level1,000 mg/dl and biliopancreatic reflux were detected in 79 and 95% of the patients, respectively.Patients with a common channelor = 5 mm (redefined HCPBD) should be monitored for the development of gallbladder cancer, as they frequently showed significant pancreatobiliary reflux.