**3.2.2 ABO-incompatible grafts**

Although ABO-identical grafts are preferred, ABO-compatible grafts (e.g., O graft; A recipient) have comparable 1-year patient survival following OLT and 49-54% 1-year graft survival (Bismuth et al., 1996a). However, ABO-incompatible grafts (e.g., A graft, B recipient) have less favorable outcomes and experience diminished 1-year graft survival rates of about 30% (Bismuth et al., 1996a). Patient survival was not affected by ABO compatibility for patients who had ALF, but the grafts suffered a greater incidence of hyperacute rejection (20%), vascular thrombosis, and/or biliary injury (56%). A Canadian group reported overall 5-year graft survival rates of 54–60% and 5-year patient survival rates of 61–77%, although the number of study subjects was small (Toso et al., 2007). The Birmingham group published their experience in liver transplantation for 29 children of < 5 kg weight, five of whom underwent for ABO-incompatible grafts. They found no difference in transplant outcome or survival between ABO- incompatible vs. ABO-compatible graft (Gelas et al., 2011). A recent meta-analysis found that ABO-incompatible grafts have excellent outcome in children but not in adult liver transplantation (Wu et al., 2011). At present, up to 60% survival of the graft is generally seen in ABO-incompatible transplants, likely related to intensive management (use of quadruple immunosuppression, postoperative plasmapheresis, splenectomy, methylprednisolone, or prostaglandin E1) (Egawa et al., 2004; Farges et al., 1995; Hanto et al., 2003; Sugawara & Makuuchi, 2006). Overall, controversy remains as to whether ABO-compatible and ABO-identical OLT leads to equivalent post-transplant outcomes. Some studies have reported no statistical difference in graft survival, while others have demonstrated that patient survival is less in ABOcompatible recipients compared to ABO-identical recipients. ABO-identical OLT is still preferred (Aladag et al., 2006; Bjoro et al., 2003; Koukoutsis et al., 2007); Smith et al., 2000).

#### **3.2.3 Auxiliary transplantation**

Auxiliary transplantation leaves the recipient's liver in place and utilizes a partial left or right lobe from the donor which acts as temporary support for the recipient's injured liver. Ideally, once the native liver recovers, immunosuppression may be withdrawn and the graft is either surgically removed or is allowed to atrophy naturally (Bismuth et al., 1996b; Chenard-Neu et al., 1995; Chenard-Neu et al., 1996). The partial graft is placed below the native liver (heterotopic auxiliary transplantation) or replaces a resected right or left native lobe (auxiliary partial liver transplantation.) While easier to perform, implantation of the heterotopic graft onto the infrahepatic vena cava may induce venous outflow obstruction, resulting in slower hepatocyte regeneration, presumably due to cytokine release from residual necrotic liver tissue. There is also an increased incidence of primary graft nonfunction and portal vein thrombosis with heterotopic auxiliary transplantation compared to auxiliary partial or whole graft OLT (Van Hoek et al., 1999). Despite a similar patient

(392) had experienced one or more psychiatric complication. Three had severe psychiatric complications, including suicide, accidental drug overdose, and suicide attempt, despite the well-being of the recipients. Although there was no clear explanation why these donors, despite detailed screening, would be at increased risk for psychiatric problems, they suggested that donors need careful preoperative assessments and perhaps prolonged post-

Although ABO-identical grafts are preferred, ABO-compatible grafts (e.g., O graft; A recipient) have comparable 1-year patient survival following OLT and 49-54% 1-year graft survival (Bismuth et al., 1996a). However, ABO-incompatible grafts (e.g., A graft, B recipient) have less favorable outcomes and experience diminished 1-year graft survival rates of about 30% (Bismuth et al., 1996a). Patient survival was not affected by ABO compatibility for patients who had ALF, but the grafts suffered a greater incidence of hyperacute rejection (20%), vascular thrombosis, and/or biliary injury (56%). A Canadian group reported overall 5-year graft survival rates of 54–60% and 5-year patient survival rates of 61–77%, although the number of study subjects was small (Toso et al., 2007). The Birmingham group published their experience in liver transplantation for 29 children of < 5 kg weight, five of whom underwent for ABO-incompatible grafts. They found no difference in transplant outcome or survival between ABO- incompatible vs. ABO-compatible graft (Gelas et al., 2011). A recent meta-analysis found that ABO-incompatible grafts have excellent outcome in children but not in adult liver transplantation (Wu et al., 2011). At present, up to 60% survival of the graft is generally seen in ABO-incompatible transplants, likely related to intensive management (use of quadruple immunosuppression, postoperative plasmapheresis, splenectomy, methylprednisolone, or prostaglandin E1) (Egawa et al., 2004; Farges et al., 1995; Hanto et al., 2003; Sugawara & Makuuchi, 2006). Overall, controversy remains as to whether ABO-compatible and ABO-identical OLT leads to equivalent post-transplant outcomes. Some studies have reported no statistical difference in graft survival, while others have demonstrated that patient survival is less in ABOcompatible recipients compared to ABO-identical recipients. ABO-identical OLT is still preferred (Aladag et al., 2006; Bjoro et al., 2003; Koukoutsis et al., 2007); Smith et al., 2000).

Auxiliary transplantation leaves the recipient's liver in place and utilizes a partial left or right lobe from the donor which acts as temporary support for the recipient's injured liver. Ideally, once the native liver recovers, immunosuppression may be withdrawn and the graft is either surgically removed or is allowed to atrophy naturally (Bismuth et al., 1996b; Chenard-Neu et al., 1995; Chenard-Neu et al., 1996). The partial graft is placed below the native liver (heterotopic auxiliary transplantation) or replaces a resected right or left native lobe (auxiliary partial liver transplantation.) While easier to perform, implantation of the heterotopic graft onto the infrahepatic vena cava may induce venous outflow obstruction, resulting in slower hepatocyte regeneration, presumably due to cytokine release from residual necrotic liver tissue. There is also an increased incidence of primary graft nonfunction and portal vein thrombosis with heterotopic auxiliary transplantation compared to auxiliary partial or whole graft OLT (Van Hoek et al., 1999). Despite a similar patient

operative monitoring (Trotter et al., 2007).

**3.2.2 ABO-incompatible grafts** 

**3.2.3 Auxiliary transplantation** 

survival rate compared to conventional OLT, unique postoperative complications may develop following auxiliary transplantation, including biliary and neurologic problems (Azoulay et al., 2001). Portal blood flow is partially diverted from the native liver to the auxiliary graft, therefore, regeneration of the native liver and graft function may be impaired. Moreover, due to the smaller mass of the transplanted liver, cerebral edema and neurologic dysfunction may continue to progress (Bismuth et al., 1996b). In addition, leaving the necrotic graft in situ following immunosuppression withdrawal may lead to the development of multi-system organ failure, or over time, cirrhosis may develop in the native liver (Chenard-Neu et al., 1996; Pereira et al., 1997).

The best outcomes with auxiliary transplantation are in young patients with hyperacute presentations due to a viral or autoimmune disorder, but this group also has the greatest chance of spontaneous recovery (Chenard-Neu et al., 1995; Chenard-Neu et al., 1996; Brandsaeter et al., 2002). Overall patient survival rate for auxiliary transplantation is reported to be between 60% and 65% and up to 85% of these survivors were able to discontinue immunosuppressive therapy by one year following transplantation (Bismuth et al., 1996b; Boudjema et al., 2002; Chenard-Neu et al., 1995; Van Hoek et al., 1999). However, those who had auxiliary partial transplantation have the greater 1-year survival rate, whereas those who underwent heterotopic transplantation had a diminished 1-year survival rate of only 33% (Van Hoek et al., 1999). Fifteen percent of the patients who underwent auxiliary transplantation had to undergo retransplantation for a variety of reasons. More recently, Faraj et al. looked at the long term outcome of 20 children who underwent auxiliary liver transplantation in the UK, the 1 and 10 year survival in this group of children was 85% (Faraj et al., 2010).
