Significant allograft dysfunction after liver transplantation

Transcription

1 Bile Duct Strictures After Adult Liver Transplantation: A Role for Biliary Reconstructive Surgery? Robert Sutcliffe, 1 Donal Maguire, 1 Andrej Mróz, 2 Bernard Portmann, 1 John O Grady, 1 Matthew Bowles, 1 Paolo Muiesan, 1 Mohamed Rela, 1 and Nigel Heaton 1 There is no accurate method to determine the functional significance of bile duct strictures after liver transplantation, and although biliary reconstructive surgery (Rouxen-Y hepaticojejunostomy, HJ) is the second-line treatment in patients with persistent allograft dysfunction following failed endoscopic therapy, there is no evidence to support this approach. Liver transplant recipients with allograft dysfunction and demonstrable bile duct strictures who had undergone hepaticojejunostomy were identified from a prospective database. Preoperative and follow-up clinical, biochemical, and radiological data were collected. Perioperative liver biopsies were evaluated prospectively by two histopathologists blinded to clinical information. The biopsies were scored according to presence and severity of biliary features, fibrosis, and coexisting diseases. The effects of preoperative factors on postoperative allograft function were analyzed using SPSS statistical software. After hepatico-jejunostomy, graft function returned to normal in 8/44 patients (18%), improved in 16/44 (36%), but remained abnormal in 20/44 (45%), including 4 patients who subsequently underwent retransplantation. Hepaticojejunostomy was more likely to yield a favorable outcome (improved or normal graft function) when performed within 2 years of transplantation. Prolonged duration of biliary obstruction was associated with development of advanced graft fibrosis at the time of surgery, but neither factor significantly influenced postoperative graft function. In conclusion, biliary reconstruction successfully restores graft function in the majority of patients who present with anastomotic strictures within the first 2 years after liver transplantation. In patients presenting with bile duct strictures late after transplantation, surgery should be reserved for selected patients without histological evidence of graft fibrosis (moderate severe) or significant nonbiliary pathology. (Liver Transpl 2004;10: ) Abbreviations: HJ, Roux-en-Y hepaticojejunostomy; OR, odds ratio; CI, confidence interval; OLT, orthotopic liver transplant. From the 1 Liver Transplant Unit, King s College Hospital, London, UK; and 2 Transplantation Institute, Warsaw, Poland. Supported by a Novartis-ESOT Study grant to A.M. Address reprint requests to Nigel Heaton, Liver Transplant Unit, King s College Hospital, Denmark Hill, London, SE5 9RS, UK. Telephone: ; FAX: ; nigel.heaton@kingshc.nhs.uk Copyright 2004 by the American Association for the Study of Liver Diseases Published online in Wiley InterScience ( DOI /lt Significant allograft dysfunction after liver transplantation is suggested by persistently raised serum liver enzymes, with elevated transaminases being indicative of acute and progressive processes such as acute cellular rejection, hepatitis, or hepatic artery thrombosis. Elevated alkaline phosphatase and gamma-glutamyl transferase are commonly seen, but are often less specific and more difficult to interpret. 1,2 A proportion of patients with cholangitic symptoms, bile duct dilatation on ultrasound, or features of bile duct obstruction on liver biopsy, will have a radiologically significant bile duct stricture on endoscopic retrograde cholangiopancreatography, 3 5 and where endoscopic therapy (either balloon dilatation or stenting) fails, 6 these patients usually undergo biliary reconstructive surgery (HJ) However, the role of surgery in the management of bile duct strictures after liver transplantation has not been established. The aims of this study were to analyze liver biopsy findings in patients with bile duct strictures, with particular reference to the presence of coexisting pathologies, and to determine the functional significance of strictures indirectly by examining the effect of biliary reconstruction on allograft function. Patients and Methods Over a 14-year period (42 whole organ liver allografts), 44 patients (24 male, 20 female, mean age years) underwent HJ because of isolated extrahepatic biliary strictures (Table 1). Preoperatively, all patients were evaluated by ultrasound and either endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography. In cases in which hepatic artery thrombosis could not be excluded by ultrasound, patients also underwent hepatic angiography. All patients underwent liver biopsy at the time of surgery. Patients were followed (median of 51 months; range 2 117) by routine clinical evaluation and liver function tests, and underwent liver biopsy when clinically indicated. Perioperative liver biopsy specimens were reviewed at the time of compilation of this report by two histopathologists who were blinded to clinical outcome. Biopsies were scored according to presence/severity of biliary features (edema and neutrophilic/eosinophilic infiltration of portal tracts, cholestasis, ductular proliferation, biliary interface activity, and deposition of copper-associated orcein-positive granules), severity of fibrosis, and presence of other pathologies. Fibrosis was scored 928 Liver Transplantation, Vol 10, No 7 ( July), 2004: pp

2 Bile Duct Strictures After Adult LT 929 Table 1. Patient Demographics Postoperative Allograft Function Improved or Resolved Progressive Total Age (yrs) Gender (female : male) 5:7 1:1 Median follow-up (months) Indication for OLT (n) Acute liver failure 4 3 Autoimmune 0 2 Hepatitis B 1 2 Hepatitis C 5 1 Primary biliary cirrhosis 5 6 Primary sclerosing cholangitis 2 0 Alcoholic liver disease 3 5 Alpha-1 antitrypsin deficiency 0 1 Budd-Chiari syndrome 1 0 Cryptogenic cirrhosis 3 0 Biliary anastomosis (n) Direct Gallbladder conduit 5 4 Roux-en-Y 3 2 T-tube (n, %) 4 (17%) 6 (30%) Cold ischaemia time (hours) Hepatic artery thrombosis (n, %) 1 2 Anastomotic stricture 17 (71%) 10 (50%) Preoperative Bilirubin (1 20 mol/l) Preoperative AST (10 50 U/L) Preoperative ALP ( U/L) Preoperative GT (1 55 U/L) Duct dilatation on ultrasonography (n, %) 14 (58%) 11 (55%) Radiological intervention (stent or balloon dilation) (n, %) 5 (21%) 6 (30%) Time from OLT to Biliary reconstruction (months) (mean SD) months from OLT to biliary reconstruction (n, %)* 8 (33%) 13 (65%) *P.04. on scale from 0 4 according to Scheuer. 12 Mean immunosuppressant drug levels (tacrolimus, cyclosporine A, or mycophenolate mofetil) were determined for each patient, but as assay methodology has changed during the study period (cyclosporine A assay changed from Fluorescent Polarization Immunoassay for the Abbott TDx analyzers (TDx FPIA) to Fluorescent Polarization Immunoassay for the Abbott AxSYM analyzers (AxSYM FPIA) on 20 January 1998; tacrolimus assay changed from IMx1 to Imx2 on 11 February 1997), for purposes of comparison, old levels were converted to current assay equivalents using derived formulas (cyclosporine A: (N 6.8)/1.33; tacrolimus: (N 1.05) 1.81). 13,14 Patients were grouped according to postoperative allograft function, and preoperative variables, including histology, were compared between groups. Statistical Analysis Continuous variables are expressed as means standard deviation. Differences between groups were analyzed using oneway analysis of variance (continuous data) and independent t test (categorical data). Statistical analysis was done using SPSS statistical software (SPSS, Chicago, IL). Results Preoperative Data Clinical and Laboratory All patients underwent orthotopic liver transplantation with ABO compatible allografts. Primary indications for orthotopic liver transplantation are presented in Table 1. Bile duct anastomoses were direct (end-toend) in 30 cases, gallbladder conduit in 9, and HJ in 5. Mean cold ischemia time was hours. Posttransplant, all 44 patients developed allograft dysfunction with an obstructive pattern of liver enzyme derangement. Mean bilirubin, aspartate transaminase, alkaline phosphatase, and gamma-glutamyl transferase

3 930 Sutcliffe et al. levels prior to HJ were mol/l, IU/L, IU/L, and IU/L, respectively. Mean bilirubin, aspartate transaminase, alkaline phosphatase, and gamma-glutamyl transferase in patients with normal/improved and abnormal allograft function were vs mol/l, vs IU/L, vs IU/L, and vs IU/L, respectively. There was no significant difference in age, gender, median followup, or indication for orthotopic liver transplantation between patients with abnormal allograft function and patients with normal or improved allograft function (Table 1). Duct dilation was evident on ultrasonographic examination in 25 patients, and endoscopic retrograde cholangiopancreatography, which was possible in 43 patients, demonstrated 27 anastomotic and 8 nonanastomotic strictures. Other diagnoses were duct dilatation (4), stones (3), and cholangiopathy (1). Hepatic artery thrombosis was diagnosed preoperatively in 3 patients. All patients (including 11 who had balloon dilatation or stent placement) underwent HJ at a median of 23 months (range 2 126) after liver transplantation. Perioperative Liver Biopsies Out of 39 available biopsy specimens, 29 (74%) displayed predominantly biliary features, alone in 20 cases and in combination with other pathological features in 9 (chronic rejection, 3; viral-like hepatitis, 1; recurrent primary biliary cirrhosis, 2; and recurrent hepatitis C, 3). Features of either rejection or disease recurrence were the most frequently observed nonbiliary pathology (32 and 37%, respectively) in patients without biliary features preoperatively (n 10; Table 2). Advanced fibrosis (grade 3 or 4) was present in 12/39% of biopsies taken at the time of HJ (31%), including biopsies taken in two patients with normal allograft function at follow-up. There was significant correlation between the duration of biliary features prior to biliary reconstruction (defined as the time between the earliest available biopsy showing biliary features and biliary reconstruction) and the presence of advanced fibrosis at the time of reconstruction (OR 1.05; 95% CI ; P.04, see Figs. 1 and 2). The median duration of biliary features in patients with and without advanced fibrosis at the time of surgery was 21 (range 1 108) and 4 months (range 1 84), respectively. Correlation between duration of biliary features and presence of advanced fibrosis was also evident on multivariate analysis, although it was not of statistical significance (P.06). Follow-Up Clinical and Laboratory After a median follow-up of 51 months (range 3 117) after HJ, allograft function returned to normal in 8 patients (18%), improved in 16 (36%), and remained abnormal in 20 (45%) (Table 2). Postoperative complications occurred in 8 patients (18%) and there were no perioperative deaths. In the group of 20 patients with abnormal allograft function, 2 patients underwent unsuccessful HJ revision at 4 months and 7 years. Four patients required retransplantation, 2 for chronic rejection and 2 for recurrent viral hepatitis (B and C). Postoperative Liver Biopsies Follow-up biopsies were available for comparison in 23 out of 44 patients (including 13 out of 20 patients with persistently abnormal allograft function; Table 2). Of 20 cases with isolated biliary features at the time of reconstruction, postoperative allograft function returned to normal in 4 (20%), improved in 6 (30%), and remained abnormal in 10 (50%). Follow-up biopsies were obtained in 9 (including 5/10 patients with abnormal postoperative allograft function) and showed persistence of biliary features in 4 (isolated in 2 and associated with rejection in 2) and presence of other pathologies in the remainder (rejection, 2; recurrent autoimmune hepatitis, 1; steatohepatitis, 1; nodular regenerative hyperplasia, 1). Where biliary features coexisted with features of other pathologies (n 9), allograft function remained abnormal in 33%, improved in 44%, and returned to normal in 22%. Follow-up biopsies, which were available in 6, showed resolution of biliary features in 3 (all with abnormal allograft function, due to hepatitis B recurrence in 1 and rejection in 2), and residual biliary features in the remaining 3 (all with an improvement in allograft function). In 3 patients who had biliary features coexisting with features of hepatitis C recurrence preoperatively, allograft function returned to normal after surgery in 2 patients, and improved in a patient who had advanced fibrosis preoperatively and persistent biliary features postoperatively. Allograft function failed to return to normal in 90% of patients (9/10), with preoperative biopsies lacking biliary features; follow-up biopsies available in 7 showed features of rejection (3), fibrosis (2), hepatitis (1), or nodular regenerative hyperplasia (1). In the 6 patients with features of rejection on preoperative biopsy (isolated in 3 and associated with biliary features in 3), follow-up biopsies showed ongo-

4 Bile Duct Strictures After Adult LT 931 Table 2. Pathological Findings Patient Primary diagnosis Preoperative pathology Preoperative advanced fibrosis Postoperative graft function Postoperative pathology 1 Alcoholic cirrhosis Rejection No Abnormal Rejection 2 Alcoholic cirrhosis Biliary Yes Abnormal 3 Alcoholic cirrhosis Biliary Yes Abnormal 4 Alcoholic cirrhosis Biliary No Abnormal Cholestasis rejection 5 Primary biliary cirrhosis Biliary No Abnormal Cholangiopathy 6 Seronegative hepatitis Biliary No Abnormal Rejection HCV 7 Acute hepatitis B Biliary Hepatitis No Abnormal HBV 8 Primary biliary cirrhosis Biliary Rejection No Abnormal Rejection 9 Alcoholic cirrhosis Biliary No Abnormal 10 Seronegative hepatitis Biliary Yes Abnormal Cholestasis rejection 11 1 antitrypsin deficiency No Abnormal 12 Primary biliary cirrhosis Biliary Rejection No Abnormal Rejection 13 Autoimmune hepatitis Biliary No Abnormal Recurrent A1 hepatitis 14 Primary biliary cirrhosis Hepatitis Yes Abnormal NRH 15 HCV cirrhosis Biliary Yes Abnormal 16 Autoimmune hepatitis Biliary No Abnormal 17 HBV cirrhosis No Abnormal HBV 18 Seronegative hepatitis Hepatitis No Abnormal Rejection 19 Primary biliary cirrhosis Ischaemia No Abnormal Fibrosis 20 Primary biliary cirrhosis Cirrhosis No Abnormal 21 Budd-Chiari syndrome Biliary Rejection No Improved Cholangiopathy 22 Primary biliary cirrhosis Biliary No Improved 23 Alcoholic cirrhosis Steatosis No Improved 24 Primary biliary cirrhosis Biliary No Improved Steatohepatitis 25 Primary biliary cirrhosis Biliary PBC No Improved 26 Drug-induced ALF No Improved 27 HBV cirrhosis No Improved 28 Primary biliary cirrhosis Biliary PBC Yes Improved Cholangiopathy NRH 29 PSC Hepatitis No Improved Biliary fibrosis 30 HCV Cirrhosis Biliary Yes Improved Cholangiopathy HCV 31 HCV Cirrhosis Biliary HCV Yes Improved Biliary HCV 32 Acute liver failure Rejection No Improved Rejection 33 Cryptogenic cirrhosis Biliary No Improved 34 Alcoholic cirrhosis Biliary Yes Improved 35 Alcoholic cirrhosis Hepatitis No Improved Hepatitis 36 Cryptogenic cirrhosis Biliary Yes Improved 37 Primary biliary cirrhosis Biliary No Normal NRH 38 PSC No Normal 39 Cryptogenic cirrhosis Biliary No Normal Rejection 40 Seronegative hepatitis Biliary Yes Normal 41 Drug-induced ALF Biliary No Normal 42 HCV Cirrhosis Biliary HCV No Normal 43 HCV Cirrhosis Rejection No Normal 44 HCV Cirrhosis Biliary HCV Yes Normal Abbreviations: ALF, acute liver failure; PSC, primary sclerosing cholangitis; NRH, nodular regenerative hyperplasia; HCV, hepatitis C virus; PBC, primary biliary cirrhosis. ing rejection in 4 (3 of whom had progressive allograft dysfunction) and cholangiopathy in 1. Of patients with follow-up biopsies that showed chronic rejection, 70% were classified perioperatively as biliary, and 36% of all biopsies that showed rejection also had biliary features. In the 4 patients with hepatitis on preoperative biopsies, postoperative biopsies showed nodular regenerative hyperplasia, biliary features with fibrosis, chronic rejection, and autoimmune-like hepatitis.

5 932 Sutcliffe et al. Table 3. Effect of Preoperative Variables on Postoperative Allograft Function Figure 1. Relationship between time (in months) of biliary reconstructive surgery after liver transplantation and postoperative allograft function. Postoperative allograft function was significantly more likely to improve or normalize in patients who underwent biliary reconstruction early (within 2 years after transplant) rather than later (70% vs. 38%; P.04). The 2-year cutoff is represented by the horizontal line. Preoperative Variable Positive Predictive Value P Value Clinical HJ 2 years post-olt 68%.04 Absence of viral etiology 51% NS Absence of PBC/PSC diagnosis 55% NS Radiology US: dilated ducts 56% NS ERCP: anastomotic stricture 63% NS Histology Presence of biliary features 55% NS Absence of co-existing pathology 50% NS Presence of advanced fibrosis 53% NS Abbreviations: US, ultrasound; OLT, orthotopic liver transplantation; PBC, primary biliary cirrhosis; PSC, primary sclerosing cholangitis. Effect of Preoperative Parameters on Postoperative Allograft Function Timing of HJ after orthotopic liver transplantation was the only factor that significantly influenced postoperative allograft function on univariate analysis. Of 23 patients, 16 (70%) who underwent early HJ (within 2 years of transplantation) had normal or improved allograft function at follow-up, in contrast to only 8 of 21 (38%) patients who had delayed HJ (OR, 3.71; 95% Figure 2. Relationship between prolonged biliary obstruction (in months) and severity of allograft fibrosis. *Duration of biliary obstruction was estimated to be the length of time between the earliest available biopsy that showed biliary features and biliary reconstructive surgery (one-way analysis of variance; P.04). Figure 3. Algorithm for management of patients with bile duct strictures after liver transplantation.

6 Bile Duct Strictures After Adult LT 933 CI ; P.04; Fig. 1). Of patients who underwent early HJ, 67% had anastomotic strictures, compared to only 29% of those who had delayed HJ (chi-squared, P.02), and allograft function improved in 63% of cases with anastomotic strictures vs. 41% of cases without (P.14). Of patients who underwent early HJ, 21% had previous endoscopic therapy, compared to 50% of patients who had delayed HJ (P.19; Fisher s exact test). Using logistic regression analysis of allograft outcome, and considering the following categorical variables: time from orthotopic liver transplantation to HJ greater than 2 years; presence of advanced fibrosis; type of stricture (anastomotic or other); and previous endoscopic therapy, there remained a strong association between timing of HJ and outcome after surgery, although it was not statistically significant (OR, 4.58; 95% CI ; P.06). Age, gender, primary diagnosis, type of biliary anastomosis, preoperative endoscopic therapy, presence of an anastomotic stricture, hepatic artery thrombosis, preoperative allograft function, or year of surgery had no significant effect on outcome after HJ (Table 1). There was no significant association between either duration of biliary features or presence of advanced fibrosis and postoperative allograft function (P.13 and.24, respectively). Timing of HJ (less than 2 years post-transplant) had a positive predictive value for normal/improved postoperative allograft function of 68%. Corresponding values for the remaining preoperative variables are shown in Table 3. There was no difference in exposure to immunosuppression between patients with abnormal and normal/improved allograft function at followup. All patients with hepatic artery thrombosis (n 3) presented with late biliary strictures. Of these, postoperative allograft function remained abnormal in 2 patients with nonanastomotic strictures, but improved in 1 patient who had an anastomotic stricture. Based on our findings, we have suggested an algorithm that may be useful in identifying which patients with bile duct strictures should be offered biliary reconstructive surgery (Fig. 3). Discussion Of this cohort of patients with demonstrable bile duct obstruction, 49% had histological evidence of nonbiliary pathology, including 26% who had no biliary features, and 27% who had advanced allograft fibrosis at the time of biliary reconstructive surgery (Table 2). Postoperatively, liver function failed to returned to normal in 82% of patients, and biliary features, when present perioperatively, resolved in only 53%. Allograft loss was due to nonbiliary causes in all 4 cases (rejection and recurrent viral hepatitis). These data suggest that the presence of coexisting disease processes contributes significantly to allograft dysfunction in this group of patients, and that bile duct obstruction plays a role in only a minority. Morbidity and graft loss associated with post-transplant bile duct strictures in earlier reports are probably due to coexisting disease processes rather than obstruction to bile flow. 3,7 9 An adverse outcome following biliary reconstructive surgery (progressive deterioration in allograft dysfunction) was significantly more likely in patients with allograft dysfunction developing more than 2 years after liver transplantation (OR, 3.71; P.04; Fig. 1). Only 1/3 of patients undergoing HJ after 2 years had anastomotic strictures, in contrast to 2/3 of patients undergoing surgery earlier (P.02). Improved allograft function after surgery was more likely in patients who had anastomotic strictures (including 1 patient with concomitant hepatic artery thrombosis) than in those without, but this was not significant (63% vs. 41%, P.14). Local factors, including injury to the vascular supply and size discrepancy between donor and recipient bile ducts, are likely to be responsible for the majority of anastomotic strictures, 1 which present early after transplantation with allograft dysfunction that is responsive to biliary reconstructive surgery. The etiology of nonanastomotic strictures is poorly understood and probably multifactorial. 7,9,15,16 Disease processes such as rejection, recurrence of primary liver disease (including hepatitis C, primary biliary cirrhosis, and primary sclerosing cholangitis), and nodular regenerative hyperplasia, although sometimes evident early after transplantation, tend to become clinically manifest later, and in such patients, a stricture may be incidental and not contributing to allograft dysfunction. It may be secondary to another pathology, such as rejection, or it may coexist with another pathology and exacerbate allograft dysfunction. Of the patients in this series, 67% had histological evidence of nonbiliary pathology (including rejection in 28%) either perioperatively or at follow-up (Table 2). Although liver biopsy plays an important role in the management of patients with allograft dysfunction, in this study the presence of either nonbiliary pathology or advanced fibrosis did not necessarily predict an adverse outcome after biliary reconstructive surgery in patients with bile duct strictures. This reflects difficulties associated with the interpretation of post-transplant liver biopsies and assessing the biological significance of anatomical strictures. 2,17,18 Sampling errors may occur if a disease process such as ischemia or fibrosis is not distributed uniformly throughout the graft parenchyma. A similar pattern of ductopenia and duct loss can be seen

7 934 Sutcliffe et al. in a variety of disease processes, including rejection and biliary obstruction, 17,18 and in the early stages it may not be possible to distinguish between the two. In our study, 70% of patients with follow-up biopsies that showed chronic rejection were classified perioperatively as biliary, and 36% of all biopsies that showed rejection also had biliary features (Table 2). Conclusions In patients with bile duct strictures after liver transplantation, allograft dysfunction is predominantly due to the presence of coexisting diseases (e.g., rejection), particularly in cases presenting more than 2 years after transplantation with nonanastomotic strictures. The presence of biliary features on liver biopsy does not predict a positive outcome after surgery, but the absence of such features argues against surgical reconstruction. Biliary reconstructive surgery is indicated for patients presenting with anastomotic strictures and early allograft dysfunction, while in patients presenting late, its role is less clear. In particular, patients with nonanastomotic strictures combined with unfavorable allograft histology (presence of severe fibrosis and lack of biliary features) are unlikely to benefit from surgery. The decision to perform biliary reconstructive surgery in patients with anastomotic bile duct strictures should be based upon careful clinical and histological evaluation. Liver biopsy is particularly important in patients with delayed allograft dysfunction and a history of viral liver disease, primary biliary cirrhosis (PBC), or primary sclerosing cholangitis (PSC) following orthotopic liver transplantation. Acknowledgment A.M. was kindly supported by an ESOT-Novartis Scholarship. References 1. Sankary HN, Williams JW, Foster PF. Can serum liver function tests differentiate rejection from other causes of liver dysfunction after hepatic transplantation? Transplant Proc 1988;20(Suppl 1): Henley KS, Lucey MR, Appelman HD, Baliga P, Brown KA, Burtch GD, et al. Biochemical and histopathological correlation in liver transplant: the first 180 days. Hepatology 1992;16: D Alessandro AM, Kalayogla M, Pirsch JD, Sollinger HW, Reed A, Knechtle SJ, et al. Biliary tract complications after orthotopic liver transplantation. Transplant Proc 1991;23: Lerut J, Gordon RD, Iwatsuki S, Esquivel CO, Todo S, Tzakis A, Starzl TE. Biliary tract complications in human orthotopic liver transplantation. Transplantation 1987;43: Letourneau JG, Castaneda-Zuniga WR. The role of radiology in the diagnosis and treatment of biliary complications after liver transplantation. Cardiovasc Intervent Radiol 1990;13: Pfau PR, Kochman ML, Lewis JD, Lang WB, Lucey MR, Olthoff K, et al. Endoscopic management of postoperative biliary complications in orthotopic liver transplantation. Gastrointest Endosc 2000;52: Colonna JO 2nd, Shaked A, Gomes AS, Colquhoun SD, Jurim O, McDiarmid SV, et al. Biliary strictures complicating liver transplantation. Incidence, pathogenesis, management, and outcome. Ann Surg 1992;216: Hernandez Q, Ramirez P, Munitiz V, Pinero A, Robles R, Sanchez-Bueno F, et al. Incidence and management of biliary tract complications following 300 consecutive orthotopic liver transplants. Transplant Proc 1999;31: Torras J, Llado L, Figueras J, Ramos E, Lama C, Fabregat J, et al. Biliary tract complications after liver transplantation: type, management, and outcome. Transplant Proc 1999;31: Lopez RR, Benner KG, Ivancek K, Keeffe EB, Deveney CW, Pinson CW. Management of biliary complications after liver transplantation. Am J Surg 1992;163: Stratta RJ, Wood RP, Langnas AN, Hollins RR, Bruder KJ, Donovan JP, et al. Diagnosis and treatment of biliary tract complications after orthotopic liver transplantation. Surgery 1989; 106: Scheuer PJ. Classification of chronic viral hepatitis: a need for reassessment. J Hepatol 1991;13: Tredger JM, Gilkes CD, Gonde CE. Therapeutic monitoring of Tacrolimus (FK506) with the first- and second-generation microparticle enzyme immunoassays: performance and results in four patient populations. Ther Drug Monit 1998;20: Tredger JM, Roberts N, Sherwood R, Higgins G, Keating J. Comparison of five Cyclosporin immunoassays with HPLC. Clin Chem Lab Med 2000;38: Scotte M, Dousset B, Calmus Y, Conti F, Houssin D, Chapius Y. The influence of cold ischemia time on biliary complications following liver transplantation. J Hepatol 1994;21: Sanchez-Urdazpal L, Gores GJ, Ward EM, Maus TP, Wahlstrom HE, Moore SB, et al. Ischemic-type biliary complications after orthotopic liver transplantation. Hepatology 1992;16: Pappo O, Ramos H, Starzl TE, Fung JJ, Demetris AJ. Structural integrity and identification of causes of liver allograft dysfunction occurring more than 5 years after transplantation. Am J Surg Pathol 1995;19: Demetris AJ, Seaberg EC, Batts KP, Ferrell L, Lee RG, Markin R, Detre K. Chronic liver allograft rejection: a National Institute of Diabetes and Digestive and Kidney Diseases interinstitutional study analyzing the reliability of current criteria and proposal of an expanded definition. National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database. Am J Surg Pathol 1998;22:28 39.