Anatomical study of the paracaval branch of the caudate lobe: implications of paracaval portion-preserving right hepatectomy for donors with marginal remnant liver volume

Abstract

Background: In living donor liver transplantation, the remnant liver volume (RLV) is important when selecting a donor, and it should usually exceed 35%. However, there have been no studies on the preservation of the caudate lobe in donors with marginal RLV. This study aimed to analyze and preserve the paracaval branch by using donor right hepatectomy (DRH). Methods: We retrospectively reviewed data from liver donors who underwent DRH between August 2022 and July 2023. The paracaval branch was classified based on its origin [right, left, or bifurcation of main portal vein (MPV)]. For the left or bifurcation types, the paracaval branch was categorized by size and the paracaval portion volume was measured. The expected preserved area after paracaval portion-preserving DRH was estimated. Results: Among the 87 donors, the paracaval branch originated from the right portal vein (RPV) in 41 (47.1%), left portal vein (LPV) in 37 (42.5%), and bifurcation in 9 (10.3%). Of 46 donors with LPV or bifurcation type, 21 (45.7%) had a large size, 13 (28.3%) had a medium size, and 12 (26.1%) had a small size. Excluding two donors with poor image quality, the liver volume of the paracaval portion averaged 38.0 mL [2.9% of the total liver volume (TLV)]. The mean expected preserved area was 27.3 mL (2.1% of the TLV). Four donors in our center underwent paracaval portion-preserving DRH, with an expected preserved area of 35.6 mL (2.7%), 164.7 mL (12.3%), and 70.2 mL (4.6%), 20.3 mL (2.0%) in each case. Conclusions: Our paracaval branch classification suggests that more than half of the donors could potentially benefit from paracaval portion-preserving DRH, particularly for large LPV or bifurcation types reaching the liver surface, thus enhancing donor safety for marginal donors with a small RLV.