Three-dimensional (3D) printing is an innovative technology that produces solid objects starting from a digital image. Recently, our group was the first to describe [24] the use of this technology in LDLT. A total of six 3D-printed livers (three donors and three recipients) were analyzed prospectively and were found to be extremely accurate in depicting the spatial relationships and dimensions of the vascular and biliary structures of the actual livers (Fig. 10.3). 3D printing, though in its infancy, offers several theoretical advantages over the current 3D screen-only graft reconstruction. Importantly, having a physical model of the liver gives the surgeon a tool for intuitive navigation of the critical anatomical structures found during surgery due to the transparency of the model and the use of color “ink” to print vascular and biliary structures. Future refinement of 3D printing and the modeling process may complement current imaging technology and provide surgeons with an additional planning tool.

Computer-assisted surgery is used in numerous fields and only recently has been introduced in liver surgery. This technology involves the use of a tracking device and a computer system that integrates, in real time, the field position of the surgical instrument with the preoperative imaging of the patient. The tracked instrument position is overlaid on multiple CT/MRI images, improving the surgeon’s spatial understanding of the vital structures that will be encountered during parenchymal dissection, thereby helping to minimize complications. While tracked surgical devices hold great potential in LDLT, the lack of accuracy during mobilization and repositioning of the liver is a current and significant limitation.

Unlike liver resection for malignancy, both portions of the graft and the remnant liver must be handled with extreme caution in donor hepatectomy. Preservation of vascular and biliary integrity on both sides of the liver is critical. Donor safety depends on preoperative knowledge of surgical anatomy, which is highly variable. The presence of multiple variants may be a relative contraindication for donation, particularly in high-risk cases.

Several important principles must be followed in donor surgery to maximize donor safety. First, contralateral hepatic ligaments should not be divided. The division of these ligaments can cause malrotation of the remnant liver, which in turn may cause catastrophic vascular insufficiency in the donor. Second, an intraoperative cholangiogram should be performed before hilar dissection to rule out anatomical variants that are not found preoperatively. Third, hepatic hilar dissection on the side of the hepatic lobe or segment should be minimized to avoid compromising blood supply to the bile duct. Fourth, a confirmatory cholangiogram should be performed after the graft liver is removed to confirm the integrity of the biliary system. Fifth, after a right hepatectomy, the falciform ligament should be tagged to the anterior abdominal wall to avoid malrotation of the remnant liver. In addition to these, the use of the liver hanging maneuver helps minimize blood loss and guides the direction of parenchymal transection [25]. Liver parenchymal division should be performed with familiar methods (CUSA, clamp-crushing technique, water-jet, bipolar coagulator, etc.) that further help minimize blood loss.

While experienced centers have performed donor hepatectomy through minimally invasive techniques, general application of this approach remains controversial due to concerns about the difficulty of controlling inadvertent massive bleeding under a laparoscopic view. Furthermore, surgical stress on living donors seems to be determined by the amount of liver mass removed during donor surgery rather than the size of incisions. Therefore, further studies and extensive discussion will be necessary before reaching a general consensus on minimally invasive donor hepatectomy.

The extent of venous reconstruction varies considerably between the left and the right lobe. The left lobe graft usually needs a simple venoplasty to optimize venous outflow on the back table [26]. In contrast, the right lobe graft frequently needs complex venous reconstruction. Reconstruction of segment five and eight veins increases the functional liver mass so that it is comparable to the extended right lobe graft with the middle hepatic vein. Vascular grafts for this reconstruction can be taken from unused vessels procured from deceased donors, cryopreserved grafts, and autologous veins such as recipient intrahepatic portal vein, internal jugular vein, and recanalized umbilical vein [27]. If these grafts are not available, expanded polytetrafluoroethylene grafts can be used with excellent early patency [28]. When two separate hepatic ducts are identified, these can be combined together using a ductoplasty technique to avoid multiple biliary reconstructions in the recipient.

Two major components of recipient surgery are essential to achieve good outcomes: excellent venous outflow to prevent graft congestion and active portal inflow modification to optimize graft hemodynamics. In the small pediatric cases, venous outflow can be maximized by making a vertical cavotomy on the retrohepatic cava from the common orifice of the three hepatic veins to create a triangular shape orifice [29]. This technique was first described in 1988, but remains the gold standard of outflow venous reconstruction in pediatric partial grafting. This technique can also be applied for the left lobe graft in adults. If the recipient venous orifice is too big and does not match the donor hepatic vein, the alternative technique for left lobe venous reconstruction is to make a horizontal cavotomy on the right side of the middle hepatic vein to enlarge the size of the common channel of the left and middle hepatic veins. In the right lobe graft, multiple venous anastomoses are frequently required, including the right hepatic veins and anterior segment branches. When a venous patch is available, multiple venous orifices can be combined together to perform one-step venous anastomosis [30]. Suboptimal venous outflow decreases functional graft size and increases the risk of graft dysfunction or failure.

In size-mismatch adult LDLT, a small graft receives excessive portal flow causing an arterial spasm via hepatic arterial buffer response, which explains the pathophysiology of SFSS [31]. Splenic artery ligation is the most frequently used technique for inflow modulation, but the effect of portal flow reduction is not always promising. Splenectomy is more effective but less frequently used due to the risk of increased blood loss and post-splenectomy sepsis [32]. Portosystemic shunt continues to be used by some centers with excellent outcomes, but there is an increased risk of portal flow steal resulting in graft hypoperfusion [33].