Post-transplant changes of segment 4 after living related liver transplantation.

The purpose of this study was to evaluate the outcome of the medial segment of the graft after living related liver transplantation (LRLT). Of the 12 pediatric recipients who underwent LRLT, 2 received whole left liver graft, 1 left lateral segment graft, and 9 extended left lateral segment grafts. The hepatic veins of the donor were reviewed and the volume of the medial segment and left lateral liver was measured before and 6 months after liver transplantation. The flow velocity and direction of the portal vein in the medial segment graft was also evaluated by Doppler ultrasound. The grafted livers of all recipients showed a substantial increase in volume of 9-120% 6 months after LRLT. For the left lateral segment, an increase in volume was found in all cases ranging from 21 to 245%. For the medial segment, volume increases of 5-48% were found in seven cases with normal hepatopetal flow detected inside the segment 4 intrahepatic portal vein. In four cases, the partial medial segment graft of the extended left lateral liver graft decreased in volume from 33 to 69%. Among these four cases, slow flow (n = 2) and hepatofugal flow (n = 1) were also detected in the intrahepatic portal vein of the medial segment. Mapping of the tributary of the hepatic veins of the graft revealed inadequate venous drainage of the partial segment 4 graft, which may be considered as the cause of the atrophic change of the partial segment 4 graft. In conclusion, different regenerative rates between the left lateral segment and the medial segment were noted, with a greater rate in the left lateral segment. The venous drainage of the medial segment is of primary concern in the determination of the outcome of the regeneration. Atrophic change occurs when inadequate hepatic venous drainage is encountered. Therefore, if an extended left lateral liver graft is required, the corresponding draining veins of the partial medial segment must be preserved. Otherwise, whole left liver or left lateral segment graft would be a better choice.