Impact of graft size mismatching on graft prognosis in liver transplantation from living donors

Background. Although living donor liver transplantation for small pediatric patients is increasingly accepted, its expansion to older/larger patients is still in question because of the lack of sufficient information on the impact of graft size mismatching. Methods. A total of 276 cases of living donor liver transplantation, excluding ABO-incompatible, auxiliary, or secondary transplants, were reviewed from graft size matching. Forty-three cases were highly urgent cases receiving intensive care preoperatively. Cases were categorized into five groups by graft-to-recipient weight ratio (GRWR): extra-small-for-size (XS; GRWR<0.8%, 17 elective and 4 urgent cases), small (S; 0.8 less than or equal to GRWR<1.0%, 21 and 7), medium (M; 1.0 less than or equal to GRWR<3.0%, 119 and 19), large (L; 3.0 less than or equal to GRWR<5.0%, 67 and 10), and extra-large era; GRWR greater than or equal to 5.0%, 9 and 3). Results. Smaller-for-size grafts were associated not only with larger and older recipients, but also with rather older donors. Posttransplant bilirubin clearance was delayed and aspartate aminotransferase corrected by relative graft size was higher in XS and S. Posttransplant hemorrhage and intestinal perforation were more frequent in XS and S, and vascular complications and acute rejection were more frequent in larger-for-size grafts. Consequently, graft survival in XS (cumulative 58% and actuarial 42% at 1 year) and S (76% and 74%) was significantly lower compared with that in M (93% and 92%) in elective cases. Graft survival in L (83% and 82%) and XL (75% and 71%) did not reach statistical significance. Conclusions. The use of small-for-size grafts (less than 1% of recipient body weight) leads to lower graft survival, probably through enhanced parenchymal cell injury and reduced metabolic and synthetic capacity. Although large-for-size grafts are associated with some anatomical and immunological disadvantages, the negative impact is less pronounced.