How are liver donors matched with recipients?

From the Guidelines

Liver donors are matched with recipients based on a combination of factors, including blood type compatibility, body size, medical urgency, and tissue typing, with the goal of maximizing transplant success and ensuring fair allocation of this scarce resource. The matching process typically begins with blood type assessment, where compatible types are identified, and size matching is crucial to ensure the donor liver fits in the recipient's abdominal cavity 1. Medical urgency is determined using the Model for End-Stage Liver Disease (MELD) score, which prioritizes the sickest patients. Although novel liver allocation systems, including ones of donor-recipient matching, may offer certain advantages, their use cannot be recommended as of yet due to the lack of robust clinical data 1.

Key Factors in Liver Donor Matching

• Blood type compatibility: ensuring the donor and recipient have compatible blood types
• Body size: considering the donor liver's size and the recipient's abdominal cavity
• Medical urgency: using the MELD score to prioritize the sickest patients
• Tissue typing: HLA matching to minimize the risk of rejection
• Geographical proximity: minimizing organ transport time to improve outcomes
• Recipient's overall health status: evaluating the recipient's medical history and current health status

Living Donor Evaluation

For living donors, a comprehensive medical evaluation is necessary to ensure the donor is healthy enough to undergo partial liver removal and that their remaining liver will function adequately 1. The liver's unique regenerative ability allows both the transplanted portion and the donor's remaining liver to grow to normal size within weeks. The live donor liver remnant should be at least 30% of pre-donation volume or mass 1.

Perfusion Preservation Strategies

Perfusion preservation strategies should be considered at different points in the donation and transplantation process to reduce adverse post-transplant outcomes, including biliary complications, in particular when using extended criteria and DCD grafts 1. Machine perfusion strategies should be used to increase the donor organ pool and organ utilisation 1.

Immunosuppression Regimens

After transplantation, immunosuppression regimens are crucial to prevent rejection. Tacrolimus trough levels should be kept at 6-10 ng/ml during the first month followed by 4-8 ng/ml thereafter 1. It is recommended to combine tacrolimus with other immunosuppressive drugs to allow for a lower range of tacrolimus trough levels and to help preserve renal function 1.

From the Research

Liver Donor Matching Process

The liver donor matching process involves several factors to ensure the best possible outcome for both the donor and the recipient. Some of the key considerations include:

• Donor variables such as age, sex, blood type, cause of death, and intensive care unit length of stay 2
• Recipient variables such as age, sex, blood type, indication for liver transplantation, and preoperative medical status 2
• The degree of T lymphocyte cross-match titer, model for end-stage liver disease (MELD) score, and graft liver volume 3
• The use of survival benefit-based allocation systems to prioritize patients on the waiting list 4

Donor Evaluation

The evaluation of living liver donors is a critical step in the matching process. This evaluation typically includes:

• Medical, physical, laboratory, psychosocial, and imaging assessments to select a suitable donor with optimal graft quality and to ensure donor safety 5
• The use of noninvasive imaging modalities to provide an accurate picture of liver vascular anatomy and liver volume measurement for surgical guidance 5
• The assessment of the donor's overall safety, including the risk of complications and the potential impact on their quality of life 6

Matching Donors and Recipients

The matching of donors and recipients is a complex process that takes into account a variety of factors, including:

• The degree of match between the donor and recipient blood types and other immunological characteristics 3
• The recipient's MELD score and other medical urgency factors 4
• The donor's liver function and other characteristics, such as age and medical history 2
• The use of desensitization protocols to reduce the risk of rejection in recipients with a positive lymphocyte cross-match 3