Paired Exchange and Donor Chains

You would think if a donor and recipient don’t have compatible blood or tissue types, the journey to donate a kidney comes to a screeching halt. Good news: it doesn't have to. 

Say you want to donate to a relative or friend, but you find out through testing that you aren't a match. If you're healthy, there's still a way you can help them get the transplant they need. 

Registries such as the National Kidney Registry  and some transplant centers help match incompatible donor/recipient pairs through a miraculous program called paired exchange. Registries use the magic of algorithms to match two incompatible pairs – willing donors who aren't a match for someone they want to donate to – for a kidney “swap” of sorts. 

How Paired Exchange Works

On a very basic level paired exchange works like this: Gavin in Los Angeles wants to donate to his wife, Yolanda. Carl in Cincinnati wants to donate to his friend Murray. Neither donor is a match for their recipient—they're known as incompatible pairs. 

At that point, Gavin and Carl can decide if they're willing to donate their kidneys to someone they don't know but match, so that their wife and friend can get a kidney—from someone they don't know but match. They say yes and register with a kidney registry. 

The registry puts computer algorithms to work and finds that Gavin is compatible with Murray and Carl is compatible with Yolanda. The two pairs do a kidney swap. Although the donors aren’t giving their kidneys to whom they originally intended, it’s a big win because it means two people receive life-saving transplants. 

Donor Chains

It gets even better if an altruistic (also known as a non-directed donor) gets thrown into the mix. An altruistic donor is someone who doesn’t have a specific person they want to donate to. They simply want to help someone who needs a kidney. (Amazing, right?) 

Since it's not part of a paired exchange, or kidney swap, an altruistic donor’s kidney becomes an “extra” kidney that can set off a chain of donations. In 2015, one altruistic donor set off a chain of 34 transplants at 26 different hospitals across the U.S. 

Sometimes a recipient who's in the registry with an incompatible donor ends up getting a kidney through a direct match or a deceased donor kidney. That donor can stay in the registry as an altruistic donor or decide not to. Those donors who stay in are usually matched quickly and become part of a chain of transplants.  

If you want to donate to someone you know but find out you're not a match, you'll have the same options available. It can be disappointing to find out you're not a match to donate directly. But on the upside, paired exchange and an altruistic donation through a registry helps two people—maybe more—get a life-saving kidney.