When an organ becomes available, several factors determine how that organ is matched to someone on the waiting list, including:
Age
Blood type
MELD score
Waiting time
Geographic distance between donor and recipient
Size of the donor organ in relation to the recipient
To start, anyone on the waiting list who isn’t a match for a donated organ is removed from the list of potential recipients. Once the list is condensed, the organ is matched with a recipient based on medical compatibility. A donor liver can be preserved for eight to 12 hours, so geography, timing, and distance from the hospital are very important. The United States is divided into 11 geographical zones to help regulate transplantation and organ allocation. Each transplant center is part of one of those 11 zones. When a donor liver becomes available in one of the 11 zones, people on the waiting list within that region are screened to determine who’s the best match.