Background : In living donor liver transplantation, remnant liver volume(RLV) is important to select a donor, usually exceeding 35%. However, there is no study on preservation of the caudate lobe in donors with marginal RLV. This study aimed to analyze paracaval branch of the caudate lobe, proposing a modified donor right hepatectomy preserving the caudate lobe.

Methods : From October 2022 to July 2023, we retrospectively reviewed liver donors undergoing right hepatectomy. Paravacal branch was classified by its origin(right, left, or bifurcation of main portal vein (PV)). For left or bifurcation types, paracaval branch was categorized by size, and liver volume of the paracaval area was estimated. Expected preserved liver volume was analyzed using a modified right hepatectomy method.

Results : Among the 87 donors, paracaval branch originated from the right PV in 41(47.1%), left PV in 37(42.5%), and bifurcation of the main PV in 9(10.3%). In 46 left or bifurcation-type donors, 21(45.7%) had a large size, 13(28.3%) had a medium size, and 12(26.1%) had a small size. The mean paracaval area volume, excluding two donors with poor image quality, was 38.0 mL, constituting 2.9% of the total liver volume(TLV). The expected preserved liver volume after modified right hepatectomy was 27.3mL, representing 2.1% of the TLV. Three donors in our center underwent paracaval branch-preserving right hepatectomy.

Conclusions : The paracaval portion of caudate lobe preserving right hepatectomy is feasible for donors with left or bifurcation types, expected to preserve 2.1% of the liver volume in those with marginal RLV, enhancing donor safety and expanding donor pool.