Paired Exchanges and Non-Directed Kidney Donation (NDD)

Paired Exchanges

Paired Exchanges, also referred to as swaps or Kidney Paired Donations, are an excellent option for recipients and donors who are not compatible with each other. The number of paired exchanges is increasing and becoming a larger share of all living kidney transplants.

Paired exchanges have also allowed a donor who doesn’t know someone who needs a kidney transplant, but wants to donate, to save the life of not just one person but many. These transplants are started by a NDD. These paired exchanges are described in more detail below.

How Does a Paired Exchange Work?
A paired exchange consists of two or more donor/recipient pairs who are not compatible with each other. Paired exchanges are a major breakthrough in living kidney donations and are revolutionizing living donor transplants by eliminating incompatibility as a barrier to donation. This provides a way for recipients and their incompatible donors to be paired with another, or more than one incompatible recipient and donor.

In the above illustration, Donor 1 is not compatible with Recipient 1, and Donor 2 is not compatible with Recipient 2. However, Donor 1 is compatible with Recipient 2 and Donor 2 is compatible with Recipient 1. If you have a donor who is not compatible with you, and they are willing to participate in a paired exchange, you can be paired with another incompatible pair. This example used 2 pairs, but any number of pairs is possible.

Non-Directed Kidney Donation (NDD)

Non-directed kidney donors, (NDD) often referred to as good Samaritan or altruistic donors are those interested in being a kidney donor but they don’t know of someone in need. These are selfless individuals that have become aware of the critical shortage of kidneys and want to help.

Unlike directed kidney donation, where one person donates to another individual, a NDD can save the life of more than one person by participating in a paired exchange. Paired exchanges have become common, in 2019 almost 20% of the living kidney transplants were from paired exchanges.

Here are two examples of how a NDD can participate in a paired exchange.

Domino Paired Kidney Exchange
In a Domino PKE, incompatible pairs, (in this example there are 2 pairs, but there could be an unlimited number of pairs,) the NDD role results in the other incompatible pairs swapping their donors so they get transplanted. The name comes from NDD allowing the other pairs to exchange their donors, having “domino” effect. With the extra NDD, another recipient can benefit, that recipient comes from the national kidney transplant waiting list.

Ongoing Donor Chains (Also called Never Ending Donor Chains)
A NDD can initiate a donor chain that has the potential of saving an unlimited number of lives.

In the example below, donor, #2 doesn’t donate in this paired exchange. Donor #2 is referred to as the “bridge donor” for the next “chain” of transplants. (In this example there are 2 pairs, but there could be an unlimited number of pairs in this or any future chain.) Donor #2 functions in the same role as the NDD and starts another chain of transplants. These chains could continue, over and over again with a new bridge donor from each new transplanted chain.

If you are interested in being a NDD there are many options one can explore. For guidance on these options, click here or email:

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