Donor selection for procurement of right posterior segment graft in living donor liver transplantation.

The right posterior segment (RPS) graft was introduced to overcome graft-size mismatch when the donor liver demonstrates a disproportionately small left lobe (LL). As variants of liver anatomy seemed to be related to the feasibility of RPS graft procurement, in 2003, we performed a prospective study to assess its feasibility in 197 consecutive living donors. Variants of the portal vein (PV) were classified as type I (bifurcation), II (trifurcation), and III (independent RPS PV branching from main PV). The right hepatic artery, vein, and bile duct were also classified according to their branching pattern and location. PV variations were type I in 157 (79.7%) donors, type II in 15 (7.6%) donors, and type III in 25 (12.7%) donors. Mean volume proportion of LL plus caudate lobe was 35.3 +/- 3.8% (range 24-4) of the whole liver volume (WLV). On exclusion of donors with LL greater than 35% of WLV, there were 14 (7.1%) donors revealing RPS greater than LL by over 3% of WLV. Of these 14 donors, 3 had type I PV with artery or bile duct anatomy not suitable for RPS procurement. One donor with type II PV and 9 out of 10 donors with type III PV met the anatomical conditions for RPS graft procurement. With the exclusion of caudate lobe volume, LL volume became less than 30% of WLV in all of these 14 donors. We successfully procured 3 RPS grafts, all with type III PV, out of 197 consecutive living donors. In conclusion, successful RPS graft procurement is highly possible, only when LL is disproportionately small (<30% of WLV) and the PV variant is type III.