The Effect of Portal Vein Variants on the Margin of Error in Graft Volume Calculation in Living Donor Right Lobe Liver Transplantation.

Background: Selecting the appropriate graft for living donor liver transplantation requires accurate calculation of estimated graft volume.

Purpose: To investigate the error rate in graft volume calculation in the preoperative evaluation of donor liver and the contribution of donor portal vein type to the error margin.

Material and methods: The study included 197 right lobe liver donors. Estimated graft volume calculations based on preoperative radiological images of donors were retrospectively reviewed. Demographic data of the donors and liver portal vein type were recorded. The proportional differences between the weight of the right lobe graft removed during transplantation and the estimated volume were calculated separately according to the portal vein groups. The margin of error in the estimated graft volume measurement and the effect of portal vein type were statistically evaluated.

Results: Considering all donors, estimated preoperative volume was calculated to be 6.877% higher than actual graft weight on average. Preoperative estimated graft volume was on average 5.746% higher for Type 1, 8.311% higher for Type 2, and finally 17.883% higher for Type 3 portal vein variant. It was shown that, as the portal vein anatomy in the donor becomes more complex, the negatively proportional difference in preoperative volume estimation increases.

Conclusion: Volume estimation showed a negative proportional difference for all three variants of the portal vein. Especially, the presence of a Type 3 portal vein in the liver graft may cause more errors in preoperative graft volume calculation.