Effects of the Bile Duct Bifurcation Angle and Position of the Living Donor on Biliary Complications in Recipients after Living Donor Liver Transplantation

Effects of the Bile Duct Bifurcation Angle and Position of the Living Donor on Biliary Complications in Recipients after Living Donor Liver Transplantation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effects of the Bile Duct Bifurcation Angle and Position of the Living Donor on Biliary Complications in Recipients after Living Donor Liver Transplantation Taku Kimura, Akira Umemura, Hiroyuki Nitta, Hirokatsu Katagiri, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7206048/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Mar, 2026 Read the published version in BMC Surgery → Version 1 posted 14 You are reading this latest preprint version Abstract Background: This study aims to search for new risk factors for biliary complications (BCs) in recipients after living donor liver transplantation (LDLT), focusing on the biliary anatomy of the donor. Methods: The study included 123 patients who underwent donor hepatectomies. Anatomical variations in biliary branching patterns, the maximum bifurcation angle of the left and right hepatic ducts, the rotation axis of the hepatic ducts, the bifurcation position of the hepatic ducts, and the bile duct diameter were evaluated with the occurrence of BCs. Results: BCs occurred in 25 recipients (20.3%), who had a larger bifurcation angle (83.6° vs. 105.9°, p = 0.001) and rotation axis (13.8° vs. 25.6°, p < 0.001), as well as a cranial bifurcation position (52.0% vs. 13.3%, p < 0.001). From the measurements obtained, cutoff values ​​were identified for the bifurcation angle of the left and right hepatic ducts at 91.8° and for the rotation axis at 30.0°. In multivariate analysis, the bifurcation angle (odds ratio [OR] 4.46), rotation axis (OR 4.96), and bifurcation position (OR 4.54) were independent risk factors. Conclusions: This study demonstrated a potential association between the biliary anatomy of donors and BCs and suggested the importance of a detailed preoperative evaluation of the donor biliary anatomy. Living donor liver transplantation biliary complication risk factor biliary anatomy living donor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction In recent years, advancements in transplantation techniques and immunosuppressive therapy have significantly improved the survival rate of recipients after living donor liver transplantation (LDLT), with the cumulative five-year survival rate in Japan reaching 80% [ 1 – 3 ]. However, the incidence of biliary complications (BCs) in recipients after LDLT remains high, reportedly being two to three times higher in LDLT than in deceased donor liver transplantation [ 4 – 6 ]. Jeon et al. reported that the right posterior bile duct anatomy of donors is an important factor in the occurrence of BCs in recipients after LDLT. They demonstrated an association between the biliary branching pattern and BCs in the right lobe graft [ 7 ]. The bifurcation of the left and right hepatic ducts occurs in a two-dimensional plane, branching to the left and right, making it easily identifiable through imaging modalities, such as direct cholangiography, drip infusion cholangiographic computed tomography (DIC-CT), and magnetic resonance cholangiopancreatography (MRCP). However, the actual bifurcation of the bile ducts forms a three-dimensional (3D) structure. As observed in the anatomy of the portal umbilical portion, the left hepatic duct runs ventrally, and the right one runs slightly dorsally. When considering the common bile duct as the central axis, this configuration results in a rightward rotational orientation. We hypothesized that living donors with BCs have the following characteristics of biliary anatomy: First, a wider bifurcation angle between the left and right hepatic ducts of living donors may result in a more acute anastomotic angle between the graft bile duct and the recipient bile duct, increasing the risk of biliary outflow obstruction. Second, if the aforementioned axial rotation is large, the bile duct orifice could face ventrally in the right liver graft and dorsally in the left liver graft possibly, making anastomosis more difficult. Moreover, if the right and left hepatic ducts bifurcate cranially to the portal vein, the bile ducts to be anastomosed may be positioned farther from the hepatic hilum, leading to excessive tension in the bile ducts. The increased distance between the bile duct or intestine of the recipient and the bile duct of the liver graft may complicate anastomosis. Based on these hypotheses, comprehensive analyses of the biliary branching pattern by anatomical features may be informative for predicting BCs. This study was designed to demonstrate that the anatomical characteristics of donors contribute to the risk of BCs and to mitigate the anatomical risk factors through preoperative simulation and intraoperative management in the future. The objective of this study was to identify novel risk factors for BCs that could be evaluated preoperatively by focusing on the biliary anatomy of the donor, independent of recipient-related factors. Materials and Methods 1 Study Subjects and Database Compilation The potential participants in this retrospective study were given the opportunity to opt out, and it was approved by the Ethics Committee of Iwate Medical University (ID number MH2019-119). From April 2007 to July 2024, 127 LDLTs were performed at Iwate Medical University Hospital in Japan. Of these, 123 living donors whose biliary anatomy was evaluated preoperatively using 3D constructed images were included in the study. Four cases from the initiation of LDLT were excluded from the present study because they were evaluated by direct cholangiography. The database was retrospectively compiled. 2 Hepatic Graft Harvesting and Biliary Anastomosis Donor hepatectomy was performed as follows: The right or left hepatic lobe was mobilized, and the hepatic veins were identified. After hepatic parenchymal transection under the Pringle maneuver, the hepatic veins were taped. The hepatoduodenal ligament was carefully dissected, and after taping the hepatic artery and portal vein, the bile duct was identified. The bile duct transection site was determined using direct cholangiography via the cystic duct until August 2017, and from September 2017 onward, it was assessed using an indocyanine green (ICG) fluorescence imaging system [8]. When we could not identify the transection line using ICG imaging, we converted it to performing direct cholangiography. Biliary anastomosis was performed through bile duct–bile duct anastomosis, bile duct–jejunal anastomosis, or a combination thereof. 3 Evaluation of Biliary Branching Anatomy 3.1 Modalities for the Assessment of Biliary Anatomy Preoperative dynamic computed chromatography (CT) and DIC-CT images of living donors were analyzed using a 3D image analysis system (SYNAPSE VINCENT, Fujifilm, Japan). 3.2 Anatomical Variations in Biliary Branching Patterns The standard type, in which the right hepatic duct is normally formed (Type I), was classified as having no anatomical variation. Other variations were classified as anomalies, including cases in which the right anterior and right posterior hepatic ducts bifurcate simultaneously (Type II), and the right posterior or anterior bile ducts drained into the left hepatic duct (Type IIIA or Type IIIB, respectively) (Fig. 1). 3.3 Maximum Bifurcation Angle of the Left and Right Hepatic Ducts and Rotation Axis of the Hepatic Ducts Using 3D reconstructed images of the bile ducts, the bifurcation angle of the left and right hepatic ducts was measured by rotating the image leftward in 5° increments from the true frontal view (0°) up to 90°. The maximum bifurcation angle (range: 0–180°) was recorded along the rotation axis of the hepatic ducts at which this maximum value was obtained (Fig. 2). Type II was considered to have a very short right hepatic duct. The midline of the right anterior and posterior bile ducts and the angle of the left hepatic duct were measured. In cases without a right hepatic duct, the angle between the right anterior bile duct and the left hepatic duct was measured (Fig. 1). 3.4 Bifurcation Position of the Left and Right Hepatic Ducts The dynamic CT and DIC-CT images were fused to create a 3D reconstruction. The intersection of the two defined straight lines measuring the bifurcation angle was assessed to determine whether it was located cranial to the primary bifurcation of the portal vein (Fig. 3). 3.5 Running of the Right Posterior Bile Duct For Types I, II, and IIIA, running of the right posterior bile duct was evaluated to determine whether it was of the supra-portal type, which refers to a pattern where the right posterior bile duct runs along the craniodorsal side of the right portal vein and joins the right anterior bile duct to form the right hepatic duct. 3.6 Bile Duct Diameter In the right liver graft cases, the maximum short-axis diameter of the right hepatic duct or the anterior sectoral duct (in cases in which the right hepatic duct was not formed) was measured. In the left liver graft cases, the maximum short-axis diameter of the left hepatic duct was measured just after the bile duct bifurcated. 4 Definition of BCs Bile leakage was defined as the bilirubin concentration in the drain fluid at least three times the serum bilirubin concentration on or after postoperative day three, or as the need for treatment intervention resulting from biliary collections or bile peritonitis [9]. Biliary stenosis was defined as a condition in which drug-induced liver damage, rejection, or worsening of the current disease was ruled out and biliary interventions were required, or the condition was accompanied by worsening liver damage or jaundice. Statistical Analysis Continuous variables were reported as the mean ± standard deviation and compared using the two-side Student’s t test for normally distributed parameters. Categorical variables were compared using Fisher’s exact test. To identify variables that were independent predictors of BCs, logistic regression analysis was conducted using variables with significant differences in univariate analysis. For the logistic regression analysis, continuous variables were converted into binary variables by determining the cutoff values using receiver operating characteristic (ROC) curve analysis. The variables were presented as the odds ratio (OR) with a confidence interval (CI) and p -value. Statistical significance was set to p < 0.05, and the statistical analyses were performed using R (version 4.4.3) and EZR (version 1.68). Results 1 Characteristics of 123 living donors The living donor group consisted of 58 males and 65 females, with a mean age of 37.8 years. There were 76 right liver grafts (61.8%) and 47 left liver grafts (28.2%). BCs occurred in 25 recipients (20.3%). Among these, 12 cases had bile leakage alone, 11 had biliary stenosis alone, and two had both bile leakage and biliary stenosis (Table 1). In the univariate analysis, no statistically significant differences were observed in the characteristics of the living donors between the groups with and without BCs (Table 2). 2 Risk factors for BCs in univariate analysis Among the overall living donors, the maximum bifurcation angle of the left and right hepatic ducts (83.6° vs. 105.9°, p = 0.001) and the rotation axis (13.8° vs. 25.6°, p < 0.001) were significantly larger in the group with BCs than in the group without BCs. In addition, in the group with BCs, a significantly higher number of cases exhibited a bifurcation position of the left and right hepatic ducts cranial to the primary branch of the portal vein ( p < 0.001). Right liver graft donors (right lobe graft, extended right lobe graft, and right posterior segment graft) exhibited similar results, with significant differences in the maximum bifurcation angle of the left and right hepatic ducts (78.2° vs. 105.9°, p = 0.001), the rotation axis (13.8° vs. 25.6°, p < 0.001), and the bifurcation position of the left and right hepatic ducts ( p < 0.001). In the left liver graft donors (left lobe graft, left lobe and Segment 1 graft, left lateral segment graft, and other grafts), significant differences were observed in the rotation axis (12.2° vs. 25.0°, p = 0.012) and the bifurcation position of the hepatic ducts ( p = 0.018) (Table 3). In the right posterior bile duct, 91.3% of the total was of the supra-portal type. There was no significant difference in the running of the bile duct between those with and without BCs (Table 4). 3 Risk factors for BCs in multivariate analysis Among the overall living donors, the ROC curve identified a cutoff value of 91.8° (area under the curve [AUC] 0.731, 95% CI 0.63–0.83) for the maximum bifurcation angle of the left and right hepatic ducts and 30.0° (AUC 0.691, 95% CI 0.56–0.82) for the rotation axis of the hepatic ducts (Fig. 4). Multivariate analysis revealed that the maximum value of the bifurcation angle of the left and right hepatic ducts (≥ 91.8°) ( p = 0.009, OR 4.46, 95% CI 1.46–13.60), the rotation axis (≥ 30°) ( p = 0.003, OR 4.96, 95% CI 1.71–14.40), and the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) ( p = 0.007, OR 4.54, 95% CI 1.51–13.70) were independent risk factors for BCs (Table 5). Similarly, in the right liver graft donors, the cutoff values were defined as 90.0° for the bifurcation angle of the right and left hepatic ducts (AUC 0.770, 95% CI 0.65–0.89) and 30.0° for the rotation axis (AUC 0.676, 95% CI 0.51–0.84). Multivariate analysis revealed that the maximum value of the bifurcation angle of the left and right hepatic ducts (≥ 90.0°) ( p = 0.009, OR 9.19, 95% CI 2.16–39.00), rotation axis (≥ 30°) ( p = 0.003, OR 6.24, 95% CI 1.50–26.00), and the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) ( p = 0.007, OR 5.30, 95% CI 1.17–24.10) were independent risk factors for BCs (Table 5). In the left liver graft donors, the cutoff value for the rotation axis of the hepatic ducts was defined as 30.0° (AUC 0.699, 95% CI 0.49–0.91). In the multivariate analysis, the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) was the only independent risk factor for BCs ( p = 0.029, OR 6.84, 95% CI 1.21–38.60) (Table 5). Discussion BCs in recipients after LDLT are complex to manage and often refractory to treatment [ 10 ]. BCs significantly affect not only recipients’ survival prognoses but also their quality of life. Therefore, reducing BCs remains a constant challenge in liver transplantation. In this study, we focused on the biliary anatomy of donors to identify novel risk factors for BCs based solely on objective donor factors that are independent of recipient characteristics and can be assessed preoperatively. Our analysis suggested an association between donor biliary anatomy and BCs. Specifically, a wider bifurcation angle of the right and left hepatic ducts, greater rightward rotation along the craniocaudal axis of the hepatic ducts, and a more cranial bifurcation position of the right and left hepatic ducts were associated with an increased incidence of BCs (Fig. 5 ). Among the overall and right liver graft donors, the bifurcation angle of the right and left hepatic ducts, the rotation axis of the bile ducts, and the bifurcation position of the right and left hepatic ducts were independent risk factors for BCs. In contrast, among left liver graft donors, only the bifurcation position of the hepatic ducts was identified as an independent risk factor. Although similar trends were observed across the overall, right liver graft, and left liver graft donors, there were slight variations between these groups. The results among the overall donors resembled those among the right liver graft donors, suggesting that the overall findings were strongly influenced by the right liver graft donors. In contrast, the left liver graft donors had fewer risk factors. The rotation axis that showed a significant difference in univariate analysis also had a low AUC. As previously mentioned, this may suggest that left lobe grafts are at a lesser risk of BCs [ 11 ]. Multiple ducts for anastomosis, ductoplasty, donor bile duct size, and multiple ducts for anastomosis have been reported as predictors of BCs [ 12 ]. These risk factors are closely associated with the complexity and difficulty of anastomosis of the bile duct, making it evident that cases with challenging anastomoses are more likely to develop BCs. In addition, right lobe grafts and ABO incompatibility have also been reported as risk factors [ 13 – 15 ]. While it is advisable to avoid known risk factors whenever possible, actual graft selection in LDLT prioritizes donor safety, graft-to-recipient weight ratio, and standard liver volume percentage for eligibility assessment. Consequently, these risks are sometimes unavoidable. Furthermore, in actual graft procurement procedures, various factors, such as the bile duct transection site and liver transection line, introduce variability, making precise preoperative prediction challenging. Jeon et al. reported that the anatomical characteristics of donor bile ducts that are prone to biliary complications are a supra-portal right posterior bile duct (RPBD), a short right hepatic duct common duct, and a long caudal segment of the RPBD [ 7 ]. They suggested that these features increase BC incidence because the bifurcation of the right anterior bile duct and RPBD is close to the liver transection plane, making them more susceptible to direct injury. In our study, cases with a small bifurcation angle of the right and left hepatic ducts predicted that the main trunks of the secondary branches of the Glissonian sheath would easily close and be exposed to the liver transection plane. If the mechanism is similar to that of the above hypothesis, the number of BCs would likely increase. However, contrary to this expectation, cases with a smaller bifurcation angle of the right and left hepatic ducts had a lower incidence of BCs. This study was conceived because of the impression that BCs are often not fully explained by technical errors alone. LDLT is a highly complex procedure requiring the full range of skills needed for hepato-biliary surgery. Thus, surgeons performing LDLT have at least average skills, and they all try to perform to the best of their abilities. Nevertheless, the incidence of BCs has not yet been reduced, and in this respect, we felt that something was off. Although technical errors are certainly a risk factor, we suspect that complications may be caused by more fundamental and physical barriers to biliary reconstruction. Early postoperative bile leakage may result from increased tension in the bile duct due to the lengthened distance between the donor and recipient bile ducts, as well as the compression of the bile duct from the dorsal side through the portal vein. In cases of postoperative cholestasis, endoscopic drainage is the first line of treatment [ 16 ]. However, we frequently encounter cases in which biliary dilation persists and jaundice is difficult to resolve, even in the absence of a clear biliary stricture in cholangiography. This suggests that postoperative cholestasis, including delayed strictures, may be due to changes in bile duct alignment caused by liver regeneration and expansion of the transection plane. To confirm this hypothesis, comparative evaluations before and after the onset of BCs are necessary, requiring further investigation. It has been reported that the greater the angle formed by the anastomosed donor and recipient bile ducts, the lower the success rate of endoscopic drainage [ 17 ]. This suggests that cases with a wider bifurcation angle not only have a higher risk of BCs but may also face challenges in successful endoscopic drainage, leading to a dual burden. Recent advancements have led to the increasing application of 3D printing in surgical planning. Park et al. reported the use of a 3D-printed model based on CT imaging to simulate graft placement in pediatric LDLT, ensuring an optimal fit within the recipient’s abdominal cavity [ 18 ]. 3D printers make it possible to reproduce not only the shape of the graft but also that of vascular structures. In the field of living donor lung transplantation, simulations using 3D printers have led to the development of a novel surgical procedure for transplanting the lower lobe of the right lung into the left thoracic cavity [ 19 ]. It is highly likely that this will be similarly useful in LDLT, in which the graft is fixed by vascular anastomosis. Therefore, we think that even greater importance should be placed on the anatomical evaluation of both donors and recipients. Further investigation of other anatomical risk factors, such as the portal vein, hepatic vein, and hepatic artery, is required in addition to biliary branching morphology. Given the persistent shortage of deceased donor liver grafts, the demand for LDLT is expected to continue to increase [ 20 – 22 ]. We hope that, in the future, if it becomes possible to perform the so-called “tailor-made put-in” for each graft, this will lead to a reduction in BCs. This study has several limitations. First, the small number of cases with BCs may have limited the identification of additional risk factors. The findings may represent only a fraction of the risk factors, necessitating the further accumulation of cases and data to allow for a more comprehensive analysis from different perspectives. In addition, this study included a mixture of left and right cases, and the incidence of BCs was low. Thus, the detection frequency was in sufficient. Second, the bile duct diameter was not evaluated after dilating the bile duct with a contrast medium, as previously reported, because the bile duct diameter was measured using DIC-CT rather than direct cholangiography. The resolution of CT images is limited, making it difficult to accurately evaluate bile ducts only a few millimeters in size from the images alone. One method for evaluating biliary diameter preoperatively is direct cholangiography through endoscopic retrograde cholangiopancreatography (ERCP), but this is an overly invasive test. Non-invasive tests, such as DIC-CT and MRCP, are adequate alternatives for the evaluation of bile duct anatomy, and we think that a new evaluation method for bile duct diameter is needed in the future [ 23 ]. Moreover, because this study focused on donors’ anatomical factors, the immune system and surgical factors were excluded. Conclusions This study demonstrated a potential association between the biliary anatomy of donors and BCs in recipients after LDLT. A larger bifurcation angle of the left and right hepatic ducts, the rotation axis of the hepatic ducts at the maximum value of the bifurcation angle of the left and right hepatic ducts, and the bifurcation position of the left and right hepatic ducts cranial to the primary branch of the portal vein were identified as significant risk factors for BCs. In the future, establishing a preoperative simulation system that takes these factors into consideration will be important for reducing BCs. Abbreviations LDLT living donor liver transplantation BCs biliary complications DIC-CT drip infusion cholangiographic computed tomography MRCT magnetic resonance cholangiopancreatography 3D three-dimensional ICG indocyanine green CT computed chromatography ROC curve receiver operating characteristic curve OR odds ratio CI confidence interval RPBD the right posterior bile duct Declarations Ethics approval and consent to participate This study was conducted in accordance with the declaration of Helsinki. This study was conducted with approval from the Ethics Committee of Iwate Medical University (ID number MH2019-119). Written informed consent was obtained from all patients. Clinical trial number: not applicable. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This study received no external funding. Authors' contributions Conceptualization, TK and AU; data curation, TK, KK, SA, DT, and HK; investigation, YI, SK, TK, and TA.; writing-original draft, TK and AU; writing-review and editing, HN and AS. All authors have read and agreed to the published version of the manuscript. Acknowledgements Not applicable. Authors' information Taku Kimura, M.D., Ph.D. Department of Surgery, Iwate Medical University School of Medicine Idai-dori 2-1-1, Yahaba-cho, Shiwa-gun, Iwate, JAPAN. Full postal: 028-3695. [email protected] References Ce F, Bw G, Aj K, As L, Tl P, Jc E, et al. Recipient morbidity after living and deceased donor liver transplantation: findings from the A2ALL Retrospective Cohort Study. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons. 2008;8. Olthoff KM, Smith AR, Abecassis M, Baker T, Emond JC, Berg CL, et al. Defining long-term outcomes with living donor liver transplantation in North America. Ann Surg. 2015;262:465–75; discussion 473-475. Humar A, Ganesh S, Jorgensen D, Tevar A, Ganoza A, Molinari M, et al. Adult Living Donor Versus Deceased Donor Liver Transplant (LDLT Versus DDLT) at a Single Center: Time to Change Our Paradigm for Liver Transplant. Ann Surg. 2019;270:444–51. Girotra M, Soota K, Klair JS, Dang SM, Aduli F. Endoscopic management of post-liver transplant biliary complications. World J Gastrointest Endosc. 2015;7:446–59. Moy BT, Birk JW. A Review on the Management of Biliary Complications after Orthotopic Liver Transplantation. J Clin Transl Hepatol. 2019;7:61–71. Boeva I, Karagyozov PI, Tishkov I. Post-liver transplant biliary complications: Current knowledge and therapeutic advances. World J Hepatol. 2021;13:66–79. Jeon YM, Lee K-W, Yi N-J, Lee JM, Hong G, Choi Y, et al. The right posterior bile duct anatomy of the donor is important in biliary complications of the recipients after living-donor liver transplantation. Ann Surg. 2013;257:702–7. Hasegawa Y, Nitta H, Takahara T, Katagiri H, Kanno S, Sasaki A. Pure laparoscopic living donor hepatectomy using the Glissonean pedicle approach (with video). Surg Endosc. 2019;33:2704–9. Koch M, Garden OJ, Padbury R, Rahbari NN, Adam R, Capussotti L, et al. Bile leakage after hepatobiliary and pancreatic surgery: a definition and grading of severity by the International Study Group of Liver Surgery. Surgery. 2011;149:680–8. Oh D-W, Lee SK, Song TJ, Park DH, Lee SS, Seo D-W, et al. Endoscopic management of bile leakage after liver transplantation. Gut Liver. 2015;9:417–23. Ikegami T, Soejima Y, Shirabe K, Taketomi A, Yoshizumi T, Uchiyama H, et al. Evolving strategies to prevent biliary strictures after living donor liver transplantation. Transplant Proc. 2010;42:3624–9. Hassouneh R, Beran A, Rosenheck M, Sosio J, Olchawa N, Kubal C, et al. Risk factors for biliary strictures and leaks after living-donor liver transplantation: a systematic review and meta-analysis. J Gastrointest Surg. 2024;28:1870–82. Sharma S, Gurakar A, Jabbour N. Biliary strictures following liver transplantation: past, present and preventive strategies. Liver Transpl. 2008;14:759–69. Kyoden Y, Tamura S, Sugawara Y, Akamatsu N, Matsui Y, Togashi J, et al. Biliary complications in right lateral sector graft live donor liver transplantation. Transpl Int. 2008;21:332–9. Gondolesi GE, Varotti G, Florman SS, Muñoz L, Fishbein TM, Emre SH, et al. Biliary complications in 96 consecutive right lobe living donor transplant recipients. Transplantation. 2004;77:1842–8. Lee SH, Ryu JK, Woo SM, Park JK, Yoo JW, Kim Y-T, et al. Optimal interventional treatment and long-term outcomes for biliary stricture after liver transplantation. Clin Transplant. 2008;22:484–93. Kim MS, Hong SK, Woo HY, Cho J-H, Lee J-M, Yoon KC, et al. Optimal Intervention for Initial Treatment of Anastomotic Biliary Complications After Right Lobe Living Donor Liver Transplantation. Transpl Int. 2022;35:10044. Park S, Choi G-S, Kim JM, Lee S, Joh J-W, Rhu J. 3D Printing Model of Abdominal Cavity of Liver Transplantation Recipient to Prevent Large-for-Size Syndrome. Int J Bioprint. 2022;8:609. Chen F, Miyamoto E, Takemoto M, Minakata K, Yamada T, Sato M, et al. Right and left inverted lobar lung transplantation. Am J Transplant. 2015;15:1716–21. Rela M, Reddy MS. Living donor liver transplant (LDLT) is the way forward in Asia. Hepatol Int. 2017;11:148–51. Tsujino T, Isayama H, Kogure H, Sato T, Nakai Y, Koike K. Endoscopic management of biliary strictures after living donor liver transplantation. Clin J Gastroenterol. 2017;10:297–311. You MS, Paik WH, Choi YH, Shin B-S, Lee SH, Ryu JK, et al. Optimal Biliary Drainage for Patients With Biliary Anastomotic Strictures After Right Lobe Living Donor Liver Transplantation. Liver Transpl. 2019;25:1209–19. Goyen M, Barkhausen J, Debatin JF, Kühl H, Bosk S, Testa G, et al. Right-lobe living related liver transplantation: evaluation of a comprehensive magnetic resonance imaging protocol for assessing potential donors. Liver Transpl. 2002;8:241–50. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 10 Mar, 2026 Read the published version in BMC Surgery → Version 1 posted Editorial decision: Revision requested 09 Sep, 2025 Reviews received at journal 31 Aug, 2025 Reviewers agreed at journal 31 Aug, 2025 Reviews received at journal 31 Aug, 2025 Reviewers agreed at journal 23 Aug, 2025 Reviews received at journal 20 Aug, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviewers invited by journal 20 Aug, 2025 Editor invited by journal 04 Aug, 2025 Editor assigned by journal 01 Aug, 2025 Submission checks completed at journal 01 Aug, 2025 First submitted to journal 24 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7206048","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":506500221,"identity":"66003357-3902-4e31-ba2f-6e15a444b6cd","order_by":0,"name":"Taku Kimura","email":"","orcid":"","institution":"Iwate Medical University Yahaba","correspondingAuthor":false,"prefix":"","firstName":"Taku","middleName":"","lastName":"Kimura","suffix":""},{"id":506500223,"identity":"d6403dbe-1cdf-468a-9259-e339783a878c","order_by":1,"name":"Akira Umemura","email":"","orcid":"","institution":"Iwate Medical University 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Yahaba","correspondingAuthor":false,"prefix":"","firstName":"Taro","middleName":"","lastName":"Ando","suffix":""},{"id":506500233,"identity":"125d31d1-0eb3-425c-b20c-1d0c3eee8d8b","order_by":8,"name":"Satoshi Amano","email":"","orcid":"","institution":"Iwate Medical University Yahaba","correspondingAuthor":false,"prefix":"","firstName":"Satoshi","middleName":"","lastName":"Amano","suffix":""},{"id":506500235,"identity":"81d0141b-582a-4af7-a7ff-ce9de50c6536","order_by":9,"name":"Toma Kawashima","email":"","orcid":"","institution":"Iwate Medical University Yahaba","correspondingAuthor":false,"prefix":"","firstName":"Toma","middleName":"","lastName":"Kawashima","suffix":""},{"id":506500236,"identity":"5715e534-bd20-46d8-842f-2411c518218e","order_by":10,"name":"Koji Kikuchi","email":"","orcid":"","institution":"Iwate Medical University Yahaba","correspondingAuthor":false,"prefix":"","firstName":"Koji","middleName":"","lastName":"Kikuchi","suffix":""},{"id":506500237,"identity":"3bcb3b61-c2bd-4043-9e9d-de9b08d7950a","order_by":11,"name":"Akira Sasaki","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+klEQVRIie3Rv4rCMBzA8V8Q6hJwbbgTXyFQKAiir2II5BYf4IYbfi51s28THFMCuhS7FlyUgrfccC7HLfenHW6Qw0g3kXyGQIYv+SUB8LybFIABGNG/LcFmDa8nqk46LZKahfPEZbBYC/v8UjzyTZHtyWzUx67dw3B1OeG5Mlm+3lGeyw4nWkVIFQeWOxJ4wgyDHY2NDB6+tBUIMwCWOAZLX+vke0vjoup+Ev0jsPfmTqCsB5snhsalDIBoIzC8cgovj9NsvpR0UlZRSLSMkvDIjesug1RFJ/wYT1gqDu9Ej/tpTx4q5nix/5p/sgzbJA1yap14nufdsV8rLFOpAJtuOgAAAABJRU5ErkJggg==","orcid":"","institution":"Iwate Medical University Yahaba","correspondingAuthor":true,"prefix":"","firstName":"Akira","middleName":"","lastName":"Sasaki","suffix":""}],"badges":[],"createdAt":"2025-07-24 13:23:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7206048/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7206048/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12893-025-03406-6","type":"published","date":"2026-03-10T15:59:48+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90308185,"identity":"00abc1cb-b675-4b70-a42a-182b1c22cddd","added_by":"auto","created_at":"2025-09-01 09:36:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":887453,"visible":true,"origin":"","legend":"\u003cp\u003eBiliary anatomy and bifurcation angle of the left and right hepatic ducts.\u003c/p\u003e\n\u003cp\u003eAbbreviations: L, the left hepatic duct; R, the right hepatic duct; RA, the right anterior bile duct; RP, the right posterior bile duct.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/066c85e73f8cbbb0eb43a2f0.png"},{"id":90310617,"identity":"462a432c-7d53-42ad-87d8-3c99cd16f937","added_by":"auto","created_at":"2025-09-01 09:44:42","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1184786,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of bifurcation angle of the left and right hepatic ducts and its rotation axis.\u003c/p\u003e\n\u003cp\u003e(A) bifurcation angle of the left and right hepatic ducts at 0°\u003c/p\u003e\n\u003cp\u003e(B) Maximum bifurcation angle of the left and right hepatic ducts at 45°\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/c456d9d295a25f0135c1b9e6.png"},{"id":90310618,"identity":"3ab44eec-50db-43c9-9505-d9b2d38ac0fb","added_by":"auto","created_at":"2025-09-01 09:44:42","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1069744,"visible":true,"origin":"","legend":"\u003cp\u003eEvaluation of bifurcation position of the left and right hepatic ducts.\u003c/p\u003e\n\u003cp\u003eYellow arrow indicates the location where the left and right portal veins branch, and red arrow indicates the intersection of lines passing through the centers of the left and right hepatic ducts.\u003c/p\u003e\n\u003cp\u003e(A) A case caudal to the primary bifurcation of the portal vein.\u003c/p\u003e\n\u003cp\u003e(B) A case cranial to the primary bifurcation of the portal vein.\u003c/p\u003e\n\u003cp\u003eAbbreviations: LHD, the left hepatic duct; RHD, the right hepatic duct; CD, the cystic duct; PV, the portal vein; LPV, the left portal vein; RPV, the right portal vein.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/947ae7e52a317640999d2907.png"},{"id":90308184,"identity":"a41f8ec4-3cd5-4bfc-9c09-b58dd94bfa4c","added_by":"auto","created_at":"2025-09-01 09:36:41","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":761008,"visible":true,"origin":"","legend":"\u003cp\u003eThe using receiver operating characteristic (ROC) curve in the overall living donors.\u003c/p\u003e\n\u003cp\u003e(A) The maximum bifurcation angle of the left and right hepatic ducts (cutoff value 91.8°, AUC 0.731, 95% CI 0.63–0.83)\u003c/p\u003e\n\u003cp\u003e(B) Rotation axis of the hepatic ducts (cutoff value 30.0°, AUC 0.691, 95 % CI 0.56–0.82).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/0934f3c2c6262f68a205e46e.png"},{"id":90308193,"identity":"74b7748c-6aa5-4630-b36b-22b2bd91a8fa","added_by":"auto","created_at":"2025-09-01 09:36:42","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2852740,"visible":true,"origin":"","legend":"\u003cp\u003e\u0026nbsp;Anatomical features associated with biliary complications (BCs) in the recipients after living donor liver transplantation.\u003c/p\u003e\n\u003cp\u003e(A) to (C) are typical images of a donor without BCs. (D) to (F) are typical images of a donor who developed BCs.\u003c/p\u003e\n\u003cp\u003e(A) 3D image of DIC-CT.\u003c/p\u003e\n\u003cp\u003e(B) coronal section image of DIC-CT.\u003c/p\u003e\n\u003cp\u003e(C) A composite image of a DIC-CT and a Dynamic CT.\u003c/p\u003e\n\u003cp\u003e(D) 3D image of DIC-CT.\u003c/p\u003e\n\u003cp\u003e(E) coronal section image of DIC-CT.\u003c/p\u003e\n\u003cp\u003e(F) A composite image of a DIC-CT and a Dynamic CT.\u003c/p\u003e\n\u003cp\u003eAbbreviations: LHD, the left hepatic duct; RHD, the right hepatic duct; CHD, the common hepatic duct; CBD, the common bile duct; CD, the cystic duct; PV, the portal vein; LPV, the left portal vein; RPV, the right portal vein.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/8a7c6430ddd09a4d2234439d.png"},{"id":104739583,"identity":"23905b73-7b55-4a55-808f-a81af095ed39","added_by":"auto","created_at":"2026-03-16 16:09:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7283257,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7206048/v1/9c87a227-4194-440d-b22d-3f67e3af7153.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effects of the Bile Duct Bifurcation Angle and Position of the Living Donor on Biliary Complications in Recipients after Living Donor Liver Transplantation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn recent years, advancements in transplantation techniques and immunosuppressive therapy have significantly improved the survival rate of recipients after living donor liver transplantation (LDLT), with the cumulative five-year survival rate in Japan reaching 80% [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, the incidence of biliary complications (BCs) in recipients after LDLT remains high, reportedly being two to three times higher in LDLT than in deceased donor liver transplantation [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eJeon et al. reported that the right posterior bile duct anatomy of donors is an important factor in the occurrence of BCs in recipients after LDLT. They demonstrated an association between the biliary branching pattern and BCs in the right lobe graft [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe bifurcation of the left and right hepatic ducts occurs in a two-dimensional plane, branching to the left and right, making it easily identifiable through imaging modalities, such as direct cholangiography, drip infusion cholangiographic computed tomography (DIC-CT), and magnetic resonance cholangiopancreatography (MRCP). However, the actual bifurcation of the bile ducts forms a three-dimensional (3D) structure. As observed in the anatomy of the portal umbilical portion, the left hepatic duct runs ventrally, and the right one runs slightly dorsally. When considering the common bile duct as the central axis, this configuration results in a rightward rotational orientation.\u003c/p\u003e\u003cp\u003eWe hypothesized that living donors with BCs have the following characteristics of biliary anatomy: First, a wider bifurcation angle between the left and right hepatic ducts of living donors may result in a more acute anastomotic angle between the graft bile duct and the recipient bile duct, increasing the risk of biliary outflow obstruction. Second, if the aforementioned axial rotation is large, the bile duct orifice could face ventrally in the right liver graft and dorsally in the left liver graft possibly, making anastomosis more difficult. Moreover, if the right and left hepatic ducts bifurcate cranially to the portal vein, the bile ducts to be anastomosed may be positioned farther from the hepatic hilum, leading to excessive tension in the bile ducts. The increased distance between the bile duct or intestine of the recipient and the bile duct of the liver graft may complicate anastomosis. Based on these hypotheses, comprehensive analyses of the biliary branching pattern by anatomical features may be informative for predicting BCs.\u003c/p\u003e\u003cp\u003eThis study was designed to demonstrate that the anatomical characteristics of donors contribute to the risk of BCs and to mitigate the anatomical risk factors through preoperative simulation and intraoperative management in the future. The objective of this study was to identify novel risk factors for BCs that could be evaluated preoperatively by focusing on the biliary anatomy of the donor, independent of recipient-related factors.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e1\u0026nbsp; \u0026nbsp; \u0026nbsp;Study Subjects and Database Compilation\u003c/p\u003e\n\u003cp\u003eThe potential participants in this retrospective study were given the opportunity to opt out, and it was approved by the Ethics Committee of Iwate Medical University (ID number MH2019-119).\u003c/p\u003e\n\u003cp\u003eFrom April 2007 to July 2024, 127 LDLTs were performed at Iwate Medical University Hospital in Japan. Of these, 123 living donors whose biliary anatomy was evaluated preoperatively using 3D constructed images were included in the study. Four cases from the initiation of LDLT were excluded from the present study because they were evaluated by direct cholangiography. The database was retrospectively compiled.\u003c/p\u003e\n\u003cp\u003e2\u0026nbsp; \u0026nbsp; \u0026nbsp;Hepatic Graft Harvesting and Biliary Anastomosis\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDonor hepatectomy was performed as follows: The right or left hepatic lobe was mobilized, and the hepatic veins were identified. After hepatic parenchymal transection under the Pringle maneuver, the hepatic veins were taped. The hepatoduodenal ligament was carefully dissected, and after taping the hepatic artery and portal vein, the bile duct was identified. The bile duct transection site was determined using direct cholangiography via the cystic duct until August 2017, and from September 2017 onward, it was assessed using an indocyanine green (ICG) fluorescence imaging system\u0026nbsp;[8]. When we could not identify the transection line using ICG imaging, we converted it to performing direct cholangiography. Biliary anastomosis was performed through bile duct–bile duct anastomosis, bile duct–jejunal anastomosis, or a combination thereof.\u003c/p\u003e\n\u003cp\u003e3\u0026nbsp; \u0026nbsp; \u0026nbsp;Evaluation of Biliary Branching Anatomy\u003c/p\u003e\n\u003cp\u003e3.1\u0026nbsp; \u0026nbsp; \u0026nbsp;Modalities for the Assessment of Biliary Anatomy\u003c/p\u003e\n\u003cp\u003ePreoperative dynamic computed chromatography (CT) and DIC-CT images of living donors were analyzed using a 3D image analysis system (SYNAPSE VINCENT, Fujifilm, Japan).\u003c/p\u003e\n\u003cp\u003e3.2\u0026nbsp; \u0026nbsp; \u0026nbsp;Anatomical Variations in Biliary Branching Patterns\u003c/p\u003e\n\u003cp\u003eThe standard type, in which the right hepatic duct is normally formed (Type I), was classified as having no anatomical variation. Other variations were classified as anomalies, including cases in which the right anterior and right posterior hepatic ducts bifurcate simultaneously (Type II), and the right posterior or anterior bile ducts drained into the left hepatic duct (Type IIIA or Type IIIB, respectively) (Fig. 1).\u003c/p\u003e\n\u003cp\u003e3.3\u0026nbsp; \u0026nbsp; \u0026nbsp;Maximum Bifurcation Angle of the Left and Right Hepatic Ducts and Rotation Axis of the Hepatic Ducts\u003c/p\u003e\n\u003cp\u003eUsing 3D reconstructed images of the bile ducts, the bifurcation angle of the left and right hepatic ducts was measured by rotating the image leftward in 5° increments from the true frontal view (0°) up to 90°. The maximum bifurcation angle (range: 0–180°) was recorded along the rotation axis of the hepatic ducts at which this maximum value was obtained (Fig. 2). Type II was considered to have a very short right hepatic duct. The midline of the right anterior and posterior bile ducts and the angle of the left hepatic duct were measured. In cases without a right hepatic duct, the angle between the right anterior bile duct and the left hepatic duct was measured (Fig. 1).\u003c/p\u003e\n\u003cp\u003e3.4\u0026nbsp; \u0026nbsp; \u0026nbsp;Bifurcation Position of the Left and Right Hepatic Ducts\u003c/p\u003e\n\u003cp\u003eThe dynamic CT and DIC-CT images were fused to create a 3D reconstruction. The intersection of the two defined straight lines\u0026nbsp;measuring the bifurcation angle was assessed to determine whether it was located cranial to the primary bifurcation of the portal vein (Fig. 3).\u003c/p\u003e\n\u003cp\u003e3.5\u0026nbsp; \u0026nbsp; \u0026nbsp;Running of the Right Posterior Bile Duct\u003c/p\u003e\n\u003cp\u003eFor Types I, II, and IIIA, running of the right posterior bile duct was evaluated to determine whether it was of the supra-portal type, which refers to a pattern where the right posterior bile duct runs along the craniodorsal side of the right portal vein and joins the right anterior bile duct to form the right hepatic duct.\u003c/p\u003e\n\u003cp\u003e3.6\u0026nbsp; \u0026nbsp; \u0026nbsp;Bile Duct Diameter\u003c/p\u003e\n\u003cp\u003eIn the right liver graft cases, the maximum short-axis diameter of the right hepatic duct or the anterior sectoral duct (in cases in which the right hepatic duct was not formed) was measured. In the left liver graft cases, the maximum short-axis diameter of the left hepatic duct was measured just after the bile duct bifurcated.\u003c/p\u003e\n\u003cp\u003e4\u0026nbsp; \u0026nbsp; \u0026nbsp;Definition of BCs\u003c/p\u003e\n\u003cp\u003eBile leakage was defined as the bilirubin concentration in the drain fluid at least three times the serum bilirubin concentration on or after postoperative day three, or as the need for treatment intervention resulting from biliary collections or bile peritonitis\u0026nbsp;[9]. Biliary stenosis was defined as a condition in which drug-induced liver damage, rejection, or worsening of the current disease was ruled out and biliary interventions were required, or the condition was accompanied by worsening liver damage or jaundice.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eContinuous variables were reported as the mean ± standard deviation and compared using the two-side Student’s \u003cem\u003et\u0026nbsp;\u003c/em\u003etest for normally distributed parameters. Categorical variables were compared using Fisher’s exact test. To identify variables that were independent predictors of BCs, logistic regression analysis was conducted using variables with significant differences in univariate analysis. For the logistic regression analysis, continuous variables were converted into binary variables by determining the cutoff values using receiver operating characteristic (ROC) curve analysis. The variables were presented as the odds ratio (OR) with a confidence interval (CI) and \u003cem\u003ep\u003c/em\u003e-value. Statistical significance was set to \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05, and the statistical analyses were performed using R (version 4.4.3) and EZR (version 1.68).\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e1\u0026nbsp; \u0026nbsp; \u0026nbsp;Characteristics of 123 living donors\u003c/p\u003e\n\u003cp\u003eThe living donor group consisted of 58 males and 65 females, with a mean age of 37.8 years. There were 76 right liver grafts (61.8%) and 47 left liver grafts (28.2%). BCs occurred in 25 recipients (20.3%). Among these, 12 cases had bile leakage alone, 11 had biliary stenosis alone, and two had both bile leakage and biliary stenosis (Table 1). In the univariate analysis, no statistically significant differences were observed in the characteristics of the living donors between the groups with and without BCs (Table 2).\u003c/p\u003e\n\u003cp\u003e2\u0026nbsp; \u0026nbsp; \u0026nbsp;Risk factors for BCs in univariate analysis\u003c/p\u003e\n\u003cp\u003eAmong the overall living donors, the maximum bifurcation angle of the left and right hepatic ducts (83.6° vs. 105.9°, \u003cem\u003ep\u003c/em\u003e = 0.001) and the rotation axis (13.8° vs. 25.6°, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) were significantly larger in the group with BCs than in the group without BCs. In addition, in the group with BCs, a significantly higher number of cases exhibited a bifurcation position of the left and right hepatic ducts cranial to the primary branch of the portal vein (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001). Right liver graft donors (right lobe graft, extended right lobe graft, and right posterior segment graft) exhibited similar results, with significant differences in the maximum bifurcation angle of the left and right hepatic ducts (78.2° vs. 105.9°, \u003cem\u003ep\u003c/em\u003e = 0.001), the rotation axis (13.8° vs. 25.6°,\u003cem\u003e\u0026nbsp;p\u003c/em\u003e \u0026lt; 0.001), and the bifurcation position of the left and right hepatic ducts (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001). In the left liver graft donors (left lobe graft, left lobe and Segment 1 graft, left lateral segment graft, and other grafts), significant differences were observed in the rotation axis (12.2° vs. 25.0°, \u003cem\u003ep\u003c/em\u003e = 0.012) and the bifurcation position of the hepatic ducts (\u003cem\u003ep\u003c/em\u003e = 0.018) (Table 3).\u003c/p\u003e\n\u003cp\u003eIn the right posterior bile duct, 91.3% of the total was of the supra-portal type. There was no significant difference in the running of the bile duct between those with and without BCs (Table 4).\u003c/p\u003e\n\u003cp\u003e3\u0026nbsp; \u0026nbsp; \u0026nbsp;Risk factors for BCs in multivariate analysis\u003c/p\u003e\n\u003cp\u003eAmong the overall living donors, the ROC curve identified a cutoff value of 91.8° (area under the curve [AUC] 0.731, 95% CI 0.63–0.83) for the maximum bifurcation angle of the left and right hepatic ducts and 30.0° (AUC 0.691, 95% CI 0.56–0.82) for the rotation axis of the hepatic ducts (Fig. 4). Multivariate analysis revealed that the maximum value of the bifurcation angle of the left and right hepatic ducts (≥ 91.8°) (\u003cem\u003ep\u003c/em\u003e = 0.009, OR 4.46, 95% CI 1.46–13.60), the rotation axis (≥ 30°) (\u003cem\u003ep\u003c/em\u003e = 0.003, OR 4.96, 95% CI 1.71–14.40), and the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) (\u003cem\u003ep\u003c/em\u003e = 0.007, OR 4.54, 95% CI 1.51–13.70) were independent risk factors for BCs (Table 5).\u003c/p\u003e\n\u003cp\u003eSimilarly, in the right liver graft donors, the cutoff values were defined as 90.0° for the bifurcation angle of the right and left hepatic ducts (AUC 0.770, 95% CI 0.65–0.89) and 30.0° for the rotation axis (AUC 0.676, 95% CI 0.51–0.84). Multivariate analysis revealed that the maximum value of the bifurcation angle of the left and right hepatic ducts (≥ 90.0°) (\u003cem\u003ep\u003c/em\u003e = 0.009, OR 9.19, 95% CI 2.16–39.00), rotation axis (≥ 30°) (\u003cem\u003ep\u003c/em\u003e = 0.003, OR 6.24, 95% CI 1.50–26.00), and the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) (\u003cem\u003ep\u003c/em\u003e = 0.007, OR 5.30, 95% CI 1.17–24.10) were independent risk factors for BCs (Table 5).\u003c/p\u003e\n\u003cp\u003eIn the left liver graft donors, the cutoff value for the rotation axis of the hepatic ducts was defined as 30.0° (AUC 0.699, 95% CI 0.49–0.91). In the multivariate analysis, the bifurcation position of the left and right hepatic ducts (cranial to the primary branch of the portal vein) was the only independent risk factor for BCs (\u003cem\u003ep\u003c/em\u003e = 0.029, OR 6.84, 95% CI 1.21–38.60) (Table 5).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eBCs in recipients after LDLT are complex to manage and often refractory to treatment [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. BCs significantly affect not only recipients\u0026rsquo; survival prognoses but also their quality of life. Therefore, reducing BCs remains a constant challenge in liver transplantation. In this study, we focused on the biliary anatomy of donors to identify novel risk factors for BCs based solely on objective donor factors that are independent of recipient characteristics and can be assessed preoperatively. Our analysis suggested an association between donor biliary anatomy and BCs. Specifically, a wider bifurcation angle of the right and left hepatic ducts, greater rightward rotation along the craniocaudal axis of the hepatic ducts, and a more cranial bifurcation position of the right and left hepatic ducts were associated with an increased incidence of BCs (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAmong the overall and right liver graft donors, the bifurcation angle of the right and left hepatic ducts, the rotation axis of the bile ducts, and the bifurcation position of the right and left hepatic ducts were independent risk factors for BCs. In contrast, among left liver graft donors, only the bifurcation position of the hepatic ducts was identified as an independent risk factor. Although similar trends were observed across the overall, right liver graft, and left liver graft donors, there were slight variations between these groups. The results among the overall donors resembled those among the right liver graft donors, suggesting that the overall findings were strongly influenced by the right liver graft donors. In contrast, the left liver graft donors had fewer risk factors. The rotation axis that showed a significant difference in univariate analysis also had a low AUC. As previously mentioned, this may suggest that left lobe grafts are at a lesser risk of BCs [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMultiple ducts for anastomosis, ductoplasty, donor bile duct size, and multiple ducts for anastomosis have been reported as predictors of BCs [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These risk factors are closely associated with the complexity and difficulty of anastomosis of the bile duct, making it evident that cases with challenging anastomoses are more likely to develop BCs. In addition, right lobe grafts and ABO incompatibility have also been reported as risk factors [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. While it is advisable to avoid known risk factors whenever possible, actual graft selection in LDLT prioritizes donor safety, graft-to-recipient weight ratio, and standard liver volume percentage for eligibility assessment. Consequently, these risks are sometimes unavoidable. Furthermore, in actual graft procurement procedures, various factors, such as the bile duct transection site and liver transection line, introduce variability, making precise preoperative prediction challenging.\u003c/p\u003e\u003cp\u003eJeon et al. reported that the anatomical characteristics of donor bile ducts that are prone to biliary complications are a supra-portal right posterior bile duct (RPBD), a short right hepatic duct common duct, and a long caudal segment of the RPBD [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. They suggested that these features increase BC incidence because the bifurcation of the right anterior bile duct and RPBD is close to the liver transection plane, making them more susceptible to direct injury. In our study, cases with a small bifurcation angle of the right and left hepatic ducts predicted that the main trunks of the secondary branches of the Glissonian sheath would easily close and be exposed to the liver transection plane. If the mechanism is similar to that of the above hypothesis, the number of BCs would likely increase. However, contrary to this expectation, cases with a smaller bifurcation angle of the right and left hepatic ducts had a lower incidence of BCs.\u003c/p\u003e\u003cp\u003eThis study was conceived because of the impression that BCs are often not fully explained by technical errors alone. LDLT is a highly complex procedure requiring the full range of skills needed for hepato-biliary surgery. Thus, surgeons performing LDLT have at least average skills, and they all try to perform to the best of their abilities. Nevertheless, the incidence of BCs has not yet been reduced, and in this respect, we felt that something was off. Although technical errors are certainly a risk factor, we suspect that complications may be caused by more fundamental and physical barriers to biliary reconstruction. Early postoperative bile leakage may result from increased tension in the bile duct due to the lengthened distance between the donor and recipient bile ducts, as well as the compression of the bile duct from the dorsal side through the portal vein. In cases of postoperative cholestasis, endoscopic drainage is the first line of treatment [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, we frequently encounter cases in which biliary dilation persists and jaundice is difficult to resolve, even in the absence of a clear biliary stricture in cholangiography. This suggests that postoperative cholestasis, including delayed strictures, may be due to changes in bile duct alignment caused by liver regeneration and expansion of the transection plane. To confirm this hypothesis, comparative evaluations before and after the onset of BCs are necessary, requiring further investigation. It has been reported that the greater the angle formed by the anastomosed donor and recipient bile ducts, the lower the success rate of endoscopic drainage [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. This suggests that cases with a wider bifurcation angle not only have a higher risk of BCs but may also face challenges in successful endoscopic drainage, leading to a dual burden.\u003c/p\u003e\u003cp\u003eRecent advancements have led to the increasing application of 3D printing in surgical planning. Park et al. reported the use of a 3D-printed model based on CT imaging to simulate graft placement in pediatric LDLT, ensuring an optimal fit within the recipient\u0026rsquo;s abdominal cavity [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. 3D printers make it possible to reproduce not only the shape of the graft but also that of vascular structures. In the field of living donor lung transplantation, simulations using 3D printers have led to the development of a novel surgical procedure for transplanting the lower lobe of the right lung into the left thoracic cavity [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. It is highly likely that this will be similarly useful in LDLT, in which the graft is fixed by vascular anastomosis. Therefore, we think that even greater importance should be placed on the anatomical evaluation of both donors and recipients. Further investigation of other anatomical risk factors, such as the portal vein, hepatic vein, and hepatic artery, is required in addition to biliary branching morphology. Given the persistent shortage of deceased donor liver grafts, the demand for LDLT is expected to continue to increase [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. We hope that, in the future, if it becomes possible to perform the so-called \u0026ldquo;tailor-made put-in\u0026rdquo; for each graft, this will lead to a reduction in BCs.\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, the small number of cases with BCs may have limited the identification of additional risk factors. The findings may represent only a fraction of the risk factors, necessitating the further accumulation of cases and data to allow for a more comprehensive analysis from different perspectives. In addition, this study included a mixture of left and right cases, and the incidence of BCs was low. Thus, the detection frequency was in sufficient. Second, the bile duct diameter was not evaluated after dilating the bile duct with a contrast medium, as previously reported, because the bile duct diameter was measured using DIC-CT rather than direct cholangiography. The resolution of CT images is limited, making it difficult to accurately evaluate bile ducts only a few millimeters in size from the images alone. One method for evaluating biliary diameter preoperatively is direct cholangiography through endoscopic retrograde cholangiopancreatography (ERCP), but this is an overly invasive test. Non-invasive tests, such as DIC-CT and MRCP, are adequate alternatives for the evaluation of bile duct anatomy, and we think that a new evaluation method for bile duct diameter is needed in the future [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Moreover, because this study focused on donors\u0026rsquo; anatomical factors, the immune system and surgical factors were excluded.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study demonstrated a potential association between the biliary anatomy of donors and BCs in recipients after LDLT. A larger bifurcation angle of the left and right hepatic ducts, the rotation axis of the hepatic ducts at the maximum value of the bifurcation angle of the left and right hepatic ducts, and the bifurcation position of the left and right hepatic ducts cranial to the primary branch of the portal vein were identified as significant risk factors for BCs. In the future, establishing a preoperative simulation system that takes these factors into consideration will be important for reducing BCs.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLDLT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eliving donor liver transplantation\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBCs\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ebiliary complications\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eDIC-CT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003edrip infusion cholangiographic computed tomography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMRCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003emagnetic resonance cholangiopancreatography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003e3D\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ethree-dimensional\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICG\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eindocyanine green\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ecomputed chromatography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eROC curve\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ereceiver operating characteristic curve\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eOR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eodds ratio\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003econfidence interval\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRPBD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ethe right posterior bile duct\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the declaration of Helsinki. This study was conducted with approval from the Ethics Committee of Iwate Medical University (ID number MH2019-119). Written informed consent was obtained from all patients.\u003c/p\u003e\n\u003cp\u003eClinical trial number: not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization, TK and AU; data curation, TK, KK, SA, DT, and HK; investigation, YI, SK, TK, and TA.; writing-original draft, TK and AU; writing-review and editing, HN and AS. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTaku Kimura, M.D., Ph.D.\u003c/p\u003e\n\u003cp\u003eDepartment of Surgery, Iwate Medical University School of Medicine\u003c/p\u003e\n\u003cp\u003eIdai-dori 2-1-1, Yahaba-cho, Shiwa-gun, Iwate, JAPAN. Full postal: 028-3695.\u003c/p\u003e\n\u003cp\[email protected]\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eCe F, Bw G, Aj K, As L, Tl P, Jc E, et al. Recipient morbidity after living and deceased donor liver transplantation: findings from the A2ALL Retrospective Cohort Study. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons. 2008;8.\u003c/li\u003e\n \u003cli\u003eOlthoff KM, Smith AR, Abecassis M, Baker T, Emond JC, Berg CL, et al. Defining long-term outcomes with living donor liver transplantation in North America. Ann Surg. 2015;262:465\u0026ndash;75; discussion 473-475.\u003c/li\u003e\n \u003cli\u003eHumar A, Ganesh S, Jorgensen D, Tevar A, Ganoza A, Molinari M, et al. Adult Living Donor Versus Deceased Donor Liver Transplant (LDLT Versus DDLT) at a Single Center: Time to Change Our Paradigm for Liver Transplant. Ann Surg. 2019;270:444\u0026ndash;51.\u003c/li\u003e\n \u003cli\u003eGirotra M, Soota K, Klair JS, Dang SM, Aduli F. Endoscopic management of post-liver transplant biliary complications. World J Gastrointest Endosc. 2015;7:446\u0026ndash;59.\u003c/li\u003e\n \u003cli\u003eMoy BT, Birk JW. A Review on the Management of Biliary Complications after Orthotopic Liver Transplantation. J Clin Transl Hepatol. 2019;7:61\u0026ndash;71.\u003c/li\u003e\n \u003cli\u003eBoeva I, Karagyozov PI, Tishkov I. Post-liver transplant biliary complications: Current knowledge and therapeutic advances. World J Hepatol. 2021;13:66\u0026ndash;79.\u003c/li\u003e\n \u003cli\u003eJeon YM, Lee K-W, Yi N-J, Lee JM, Hong G, Choi Y, et al. The right posterior bile duct anatomy of the donor is important in biliary complications of the recipients after living-donor liver transplantation. Ann Surg. 2013;257:702\u0026ndash;7.\u003c/li\u003e\n \u003cli\u003eHasegawa Y, Nitta H, Takahara T, Katagiri H, Kanno S, Sasaki A. Pure laparoscopic living donor hepatectomy using the Glissonean pedicle approach (with video). Surg Endosc. 2019;33:2704\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eKoch M, Garden OJ, Padbury R, Rahbari NN, Adam R, Capussotti L, et al. Bile leakage after hepatobiliary and pancreatic surgery: a definition and grading of severity by the International Study Group of Liver Surgery. Surgery. 2011;149:680\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eOh D-W, Lee SK, Song TJ, Park DH, Lee SS, Seo D-W, et al. Endoscopic management of bile leakage after liver transplantation. Gut Liver. 2015;9:417\u0026ndash;23.\u003c/li\u003e\n \u003cli\u003eIkegami T, Soejima Y, Shirabe K, Taketomi A, Yoshizumi T, Uchiyama H, et al. Evolving strategies to prevent biliary strictures after living donor liver transplantation. Transplant Proc. 2010;42:3624\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eHassouneh R, Beran A, Rosenheck M, Sosio J, Olchawa N, Kubal C, et al. Risk factors for biliary strictures and leaks after living-donor liver transplantation: a systematic review and meta-analysis. J Gastrointest Surg. 2024;28:1870\u0026ndash;82.\u003c/li\u003e\n \u003cli\u003eSharma S, Gurakar A, Jabbour N. Biliary strictures following liver transplantation: past, present and preventive strategies. Liver Transpl. 2008;14:759\u0026ndash;69.\u003c/li\u003e\n \u003cli\u003eKyoden Y, Tamura S, Sugawara Y, Akamatsu N, Matsui Y, Togashi J, et al. Biliary complications in right lateral sector graft live donor liver transplantation. Transpl Int. 2008;21:332\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eGondolesi GE, Varotti G, Florman SS, Mu\u0026ntilde;oz L, Fishbein TM, Emre SH, et al. Biliary complications in 96 consecutive right lobe living donor transplant recipients. Transplantation. 2004;77:1842\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eLee SH, Ryu JK, Woo SM, Park JK, Yoo JW, Kim Y-T, et al. Optimal interventional treatment and long-term outcomes for biliary stricture after liver transplantation. Clin Transplant. 2008;22:484\u0026ndash;93.\u003c/li\u003e\n \u003cli\u003eKim MS, Hong SK, Woo HY, Cho J-H, Lee J-M, Yoon KC, et al. Optimal Intervention for Initial Treatment of Anastomotic Biliary Complications After Right Lobe Living Donor Liver Transplantation. Transpl Int. 2022;35:10044.\u003c/li\u003e\n \u003cli\u003ePark S, Choi G-S, Kim JM, Lee S, Joh J-W, Rhu J. 3D Printing Model of Abdominal Cavity of Liver Transplantation Recipient to Prevent Large-for-Size Syndrome. Int J Bioprint. 2022;8:609.\u003c/li\u003e\n \u003cli\u003eChen F, Miyamoto E, Takemoto M, Minakata K, Yamada T, Sato M, et al. Right and left inverted lobar lung transplantation. Am J Transplant. 2015;15:1716\u0026ndash;21.\u003c/li\u003e\n \u003cli\u003eRela M, Reddy MS. Living donor liver transplant (LDLT) is the way forward in Asia. Hepatol Int. 2017;11:148\u0026ndash;51.\u003c/li\u003e\n \u003cli\u003eTsujino T, Isayama H, Kogure H, Sato T, Nakai Y, Koike K. Endoscopic management of biliary strictures after living donor liver transplantation. Clin J Gastroenterol. 2017;10:297\u0026ndash;311.\u003c/li\u003e\n \u003cli\u003eYou MS, Paik WH, Choi YH, Shin B-S, Lee SH, Ryu JK, et al. Optimal Biliary Drainage for Patients With Biliary Anastomotic Strictures After Right Lobe Living Donor Liver Transplantation. Liver Transpl. 2019;25:1209\u0026ndash;19.\u003c/li\u003e\n \u003cli\u003eGoyen M, Barkhausen J, Debatin JF, K\u0026uuml;hl H, Bosk S, Testa G, et al. Right-lobe living related liver transplantation: evaluation of a comprehensive magnetic resonance imaging protocol for assessing potential donors. Liver Transpl. 2002;8:241\u0026ndash;50.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Living donor liver transplantation, biliary complication, risk factor, biliary anatomy, living donor","lastPublishedDoi":"10.21203/rs.3.rs-7206048/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7206048/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground:\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis study aims to search for new risk factors for biliary complications (BCs) in recipients after living donor liver transplantation (LDLT), focusing on the biliary anatomy of the donor.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods:\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe study included 123 patients who underwent donor hepatectomies. Anatomical variations in biliary branching patterns, the maximum bifurcation angle of the left and right hepatic ducts, the rotation axis of the hepatic ducts, the bifurcation position of the hepatic ducts, and the bile duct diameter were evaluated with the occurrence of BCs.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults:\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBCs occurred in 25 recipients (20.3%), who had a larger bifurcation angle (83.6\u0026deg; vs. 105.9\u0026deg;, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) and rotation axis (13.8\u0026deg; vs. 25.6\u0026deg;, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), as well as a cranial bifurcation position (52.0% vs. 13.3%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). From the measurements obtained, cutoff values ​​were identified for the bifurcation angle of the left and right hepatic ducts at 91.8\u0026deg; and for the rotation axis at 30.0\u0026deg;. In multivariate analysis, the bifurcation angle (odds ratio [OR] 4.46), rotation axis (OR 4.96), and bifurcation position (OR 4.54) were independent risk factors.\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusions:\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis study demonstrated a potential association between the biliary anatomy of donors and BCs and suggested the importance of a detailed preoperative evaluation of the donor biliary anatomy.\u003c/p\u003e","manuscriptTitle":"Effects of the Bile Duct Bifurcation Angle and Position of the Living Donor on Biliary Complications in Recipients after Living Donor Liver Transplantation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-01 09:36:36","doi":"10.21203/rs.3.rs-7206048/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-09T08:42:10+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-31T20:01:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250985104023604695757099369073354544502","date":"2025-08-31T19:57:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-31T11:08:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"73255214965494439744419851876440904585","date":"2025-08-23T16:37:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-20T19:11:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6853554783973992202159545295337916244","date":"2025-08-20T18:42:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"284421218923025408958026386691924639381","date":"2025-08-20T17:28:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"19097812727031539112699199996429835014","date":"2025-08-20T15:26:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-20T14:47:10+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-08-04T06:46:10+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-01T11:09:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-01T11:08:47+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Surgery","date":"2025-07-24T13:17:55+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bsur","sideBox":"Learn more about [BMC Surgery](http://bmcsurg.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bsur/default.aspx","title":"BMC Surgery","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9d875293-ea56-4fcc-9f42-2f7f4aacda71","owner":[],"postedDate":"September 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-16T16:05:12+00:00","versionOfRecord":{"articleIdentity":"rs-7206048","link":"https://doi.org/10.1186/s12893-025-03406-6","journal":{"identity":"bmc-surgery","isVorOnly":false,"title":"BMC Surgery"},"publishedOn":"2026-03-10 15:59:48","publishedOnDateReadable":"March 10th, 2026"},"versionCreatedAt":"2025-09-01 09:36:36","video":"","vorDoi":"10.1186/s12893-025-03406-6","vorDoiUrl":"https://doi.org/10.1186/s12893-025-03406-6","workflowStages":[]},"version":"v1","identity":"rs-7206048","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7206048","identity":"rs-7206048","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}