Two grafts, one implant: ex vivo assembly and en bloc piggyback implantation for dual-graft liver transplantation

Dual-graft liver transplantation (DGLT) is a recognized option for selected adult recipients with severe graft-to-recipient size mismatch when graft-size adequacy must be balanced against donor safety and a single partial graft of acceptable donor risk cannot provide adequate functional liver mass (1-3). In most centers, DGLT is performed sequentially, with implantation and reperfusion of the first graft followed by implantation and vascular/biliary reconstruction of the second graft. During this sequence, the second graft remains in cold preservation while the first graft is implanted and reperfused, which may extend its waiting time before reperfusion and complicate intraoperative hemodynamic management and graft placement in the abdomen (4,5). We developed an ex vivo assembly approach in which two partial grafts are reconstructed and integrated on the back-table to enable piggyback en bloc implantation with simultaneous portal reperfusion. This workflow was designed to simplify recipient-side reconstruction and enable simultaneous portal reperfusion without altering standard transplant indications. Here, we report three consecutive adult DGLT cases performed using an ex vivo assembly and en bloc piggyback implantation technique at West China Hospital of Sichuan University.

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments, and was approved by the Ethics Committee of West China Hospital, Sichuan University (No. 2025-2107). Given the retrospective, non-interventional design, the requirement for additional informed consent for this analysis was waived. Three adult recipients underwent DGLT using an ex vivo assembly approach between November 2019 and January 2025. Recipient selection and deceased donor (DD) graft allocation followed standard institutional and national transplant protocols, and immunosuppression and perioperative care followed standard institutional liver transplantation practice. Case 1 was a 46-year-old man (66 kg) with recurrent hepatocellular carcinoma (HCC) after resection. The living donor (LD) was his 23-year-old niece, and volumetry estimated a right lobe (RL) graft without the middle hepatic vein (MHV) of 438.1 mL, corresponding to a predicted graft-to-recipient weight ratio (GRWR) of 0.66%. A DD provided a left lateral segment (LLS) graft weighing 400 g, and the final configuration was RL + LLS. Case 2 was a 52-year-old man (60 kg) with recurrent HCC after resection. The LD was his wife. Volumetry estimated RL and left lobe (LL) graft volumes of 747.3 and 378.5 mL, respectively. RL donation was avoided because the predicted donor remnant liver volume would have been 33.6%. A DD provided an LL graft weighing 318 g, and the final configuration was LL + LL. Case 3 was a 36-year-old woman (56 kg) with polycystic liver disease. The LD was her father. Volumetry estimated RL and LL graft volumes of 755.8 and 229.8 mL, respectively. RL donation was contraindicated because the predicted donor remnant liver volume would have been 23.3%. A DD provided an LL graft weighing 389 g, and the final configuration was LL + LL.

In all cases, graft 1 was procured from the LD via laparoscopic donor hepatectomy (6). Graft 2 was obtained by in situ split procurement from a DD, and the corresponding split grafts were transplanted successfully into other recipients without major graft-related complications. In case 1, graft 2 was an LLS including the left hepatic vein (LHV). In cases 2 and 3, graft 2 was an LL including the MHV and was procured en bloc with the retrohepatic inferior vena cava (IVC). For graft 2, the donor main portal vein and proximal common/proper hepatic artery were preserved as future common inflow conduits, with the left portal/arterial branches supplying graft 2 and short right portal/arterial stumps retained for inter-graft anastomoses.

Ex vivo assembly was performed on the back-table in parallel with recipient hepatectomy, with both grafts maintained in cold preservation. The goal was to create a single venous outflow cuff, a common portal inflow for end-to-end anastomosis with the recipient main portal vein, and a single arterial conduit, thereby consolidating the two grafts into one composite graft and reducing the number of recipient-side anastomoses. In case 1 (RL + LLS; Figure 1A,1B), graft 1 was the LD-RL and graft 2 was the DD-LLS. The right hepatic vein (RHV) of graft 1 and the LHV of graft 2 were unified using a venous patch to form the outflow cuff. For the portal system, the right portal vein (RPV) of graft 1 was anastomosed end-to-end to the RPV stump of graft 2, allowing the main portal vein of graft 2 to serve as the common inflow. For the arterial system, the right hepatic artery (RHA) of graft 1 was anastomosed end-to-end to the RHA stump of graft 2, and the proximal common/proper hepatic artery of graft 2 was preserved as the single arterial conduit. In cases 2 and 3 (LL + LL), graft 2 (DD-LL with the retrohepatic IVC) was rotated 180° and positioned to the right of graft 1 (LD-LL) to optimize vascular alignment. The LHV of graft 1 was anastomosed to the RHV orifice on graft 2’s IVC cuff to unify venous outflow. The left portal vein and left hepatic artery of graft 1 were then anastomosed end-to-end to the RPV and RHA stumps of graft 2, respectively, allowing the main portal vein and proximal hepatic artery of graft 2 to serve as the common inflow conduits (Figure 1C,1D). After completion of the back-table anastomoses, cold perfusion was resumed and leak testing was performed to confirm anastomotic integrity and assess vessel patency.

Figure 1.

Stepwise ex vivo assembly and en bloc piggyback implantation for DGLT. (A) Schematic illustration of the stepwise ex vivo assembly process in the RL + LLS configuration, showing back-table reconstruction of graft 1 (LD-RL) and graft 2 (DD-LLS) to create a unified venous outflow, common portal inflow, and single arterial conduit. (B) Intraoperative photographs showing the key venous, portal, and arterial anastomoses in the RL + LLS configuration. (C) Schematic illustration of the stepwise ex vivo assembly process in the LL + LL configuration, showing 180° rotation of graft 2 (DD-LL with retrohepatic IVC) and subsequent alignment with graft 1 (LD-LL) for venous, portal, and arterial reconstruction. (D) Intraoperative photographs showing the final LL + LL configuration after completion of venous outflow, portal inflow, and arterial reconstruction. Purple, portal vein; red, hepatic artery; green, bile duct; blue, IVC. DD, deceased donor; DGLT, dual-graft liver transplantation; IVC, inferior vena cava; LD, living donor; LHA, left hepatic artery; LHV, left hepatic vein; LL, left lobe; LLS, left lateral segment; LPV, left portal vein; MPV, main portal vein; PHA, proper hepatic artery; RHA, right hepatic artery; RHV, right hepatic vein; RL, right lobe; RPV, right portal vein.

All recipients underwent orthotopic liver transplantation using a piggyback en bloc implantation technique. Recipient hepatectomy was performed with preservation of the IVC. A piggyback hepatic venous cuff was created by uniting the RHV, MHV, and LHV orifices on the preserved IVC, and the unified venous outflow cuff of the composite graft was anastomosed to this recipient cuff in an end-to-side fashion. The reconstructed portal inflow was anastomosed end-to-end to the recipient main portal vein, and both grafts were reperfused simultaneously after portal vein unclamping. Arterial reconstruction was then completed end-to-end between the composite graft arterial conduit (from graft 2) and the recipient proper hepatic artery. Intraoperative Doppler ultrasonography was used to confirm hepatic arterial pulsatility, portal inflow, and venous outflow, and graft positioning was adjusted as needed to avoid torsion, kinking, or compression.

Recipient hepatectomy accounted for most of the variability in operative time. Dense adhesions from prior abdominal surgery in cases 1 and 2, and limited working space due to polycystic liver disease in case 3, largely explained the prolonged hepatectomy times of 365, 283, and 521 minutes and overall operative times of 815, 548, and 825 minutes. The standardized phases were more consistent, with ex vivo assembly completed in 75, 65, and 55 minutes and the anhepatic phase lasting 60, 71, and 89 minutes. All LDs recovered without complications, and there was no perioperative mortality among recipients. In case 3, early biopsy-proven acute rejection of the LD graft (left-sided graft) responded to anti-rejection therapy, and a pleural effusion required thoracentesis followed by chest tube placement. No other recipient experienced a Clavien-Dindo grade III or higher complication. All recipients were alive at last follow-up, ranging from 13 to 71 months, and were independent in activities of daily living.

Discussion

This brief series supports the technical feasibility of ex vivo assembly with en bloc implantation in carefully selected adult DGLT cases. The key distinction from conventional sequential DGLT (4,5) is that inter-graft venous, portal, and arterial reconstruction is completed on the back-table before a single en bloc implantation. By shifting key vascular reconstruction to the back-table, the recipient phase can be streamlined in a controlled, bloodless setting with improved exposure, which may enhance anastomotic precision and reduce technical complexity. At a given graft procurement time, en bloc implantation may limit the additional recipient-side cold-preservation interval that the second graft would otherwise incur during sequential implantation and permit simultaneous portal reperfusion. This interval can be particularly pronounced in LL + LL transplantation, in which biliary reconstruction may precede portal reperfusion in some sequential workflows (1,5). Simultaneous reperfusion may theoretically distribute portal venous return between the two grafts from the outset and avoid an interval in which portal inflow is directed to only one partial graft. Elevated portal pressure and shear stress have been linked to sinusoidal endothelial injury, endothelial dysfunction, parenchymal injury, and microcirculatory disturbance (7-10). This potential physiologic rationale warrants further evaluation with quantitative hemodynamic assessment. In addition, because back-table reconstruction can proceed in parallel with recipient hepatectomy, this approach supports a two-team workflow and may help maintain efficiency.

The present report is limited by its small sample size, retrospective single-center design, lack of a control group, heterogeneous follow-up, and inclusion only of cases combining one LD partial graft with one DD split graft. Therefore, any extrapolation to DGLT using two LD grafts should be made with caution, because donor-safety constraints may limit vascular length and the availability of expendable vascular conduits for ex vivo assembly. Larger studies with standardized reporting of ischemia and hemodynamic parameters are needed to clarify which anatomic configurations benefit most from ex vivo assembly and to define long-term outcomes.

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments, and was approved by the Ethics Committee of West China Hospital, Sichuan University (No. 2025-2107). Given the retrospective, non-interventional design, the requirement for additional informed consent for this analysis was waived.