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Incompatible Kidney Transplant Program

Often, patients who need a kidney transplant have a living donor. Unfortunately, many living donors may not have blood or tissue types that match the recipient. If the donor organ does not match the recipient’s blood and tissue, the transplant will fail. Incompatible donor/patient pairs may be interested in one of our Incompatible Kidney Transplant programs.

In this section:

Blood Compatibility

Living transplant donors and recipients should have matching or compatible blood types to decrease the risk of organ rejection. If you are unsure of your blood type, your physician will review this information with you during your evaluation process. Blood type is based on surface antigens on your red blood cells, and are grouped into categories named A, B, AB, or O. Blood type is genetically determined, so it is likely that a close family member shares your blood type.

Positive Crossmatch and Sensitized Patients

About 30% of transplant patients are sensitized. This means that they have harmful antibodies which will attack foreign tissue, such as the transplanted organ from a living donor. These antibodies develop through a previous exposure to foreign tissue, such as through pregnancy, previous transplants, or blood transfusions. Sensitized patients may wait three to four times longer than unsensitized patients for a compatible deceased donor kidney.

To test a recipient for these antibodies, a sample of their blood is mixed with a sample of the potential donor’s blood. This test is called a “crossmatch,” and shows how a recipient’s antibodies react with the potential donor’s. Test results can be either positive or negative. It may seem confusing at first, but a positive crossmatch means that a donor and recipient are not compatible.

A positive crossmatch results in the recipient’s antibodies attacking the donor’s which means the kidney is not suitable for transplant.

A negative crossmatch means that the recipient’s antibodies do not attack the donor’s which means the kidney is suitable for transplant.

  • Positive Crossmatch:

    A positive crossmatch results in the recipient’s antibodies attacking the donor’s which means the kidney is not suitable for transplant.

  • Negative Crossmatch:

    A negative crossmatch means that the recipient’s antibodies do not attack the donor’s which means the kidney is suitable for transplant.

If a donor and recipient are not compatible, a transplant can still be performed. Experts at the Johns Hopkins Comprehensive Transplant Center developed a method call plasmapheresis, which helps make a kidney more compatible for a recipient and significantly affects survival outcomes.


What is a Paired Kidney Exchange?

Since 2001, Johns Hopkins Comprehensive Transplant Center has participated in paired kidney exchanges. A paired kidney exchange, also known as a “kidney swap” occurs when a living kidney donor is incompatible with the recipient, and so exchanges kidneys with another donor/recipient pair. Two live donor transplants would occur. Suppose there were two donor/recipient pairs, Donor and Recipient 1 and Donor and Recipient 2:

  • Donor 1 would give a kidney to Recipient 2.
  • Donor 2 would then give a kidney to Recipient 1.

This kidney paired donation transplant enables two incompatible recipients to receive healthy, more compatible kidneys. All medically eligible donor/recipient pairs may participate in the paired kidney exchange program.

In more complex cases, additional donor/recipient pairs may be used. Participating in the paired kidney exchange program allows for a recipient to receive a better matched kidney, and helps other individuals who would otherwise continue to wait for a matched donor. Approximately 45% of donor/recipient pairs could find a perfectly matched donor by entering the national paired kidney exchange program.

  • For many years, matching potential donor/recipient pairs was managed through the local hospital, or through partnering with area hospitals. Recently, The Organ Procurement and Transplantation Network started a Kidney Paired Donation program that will find matching donor/recipient pairs throughout the United States.  Johns Hopkins experts anticipate that, each year, an additional 1,000 – 2,000 donations can be performed through this national program.

  • It can take anywhere from one month to two years to find an exchange pair. This depends on the donor/recipient antibody levels, blood type and the number of people in the database.

  • If the surgery is a simple exchange between two donor/recipient pairs, the Johns Hopkins Comprehensive Transplant Center will typically remove the kidneys from the donors in the morning and transplant to the recipients in the afternoon. There may be times, however, when one transplant surgery may be scheduled a few weeks after the other. If multiple donor/recipient pairs are involved, the process may take several weeks.

    If other hospitals are involved, there is a chance that a donor may be asked to travel to their location. If this is the case, the donor will be assigned a coordinator, surgeon and nephrologist at this hospital. Most hospitals will accept a donor’s kidney that has been shipped. Research has shown the living donor kidneys can be stored in preservation fluid for up to eight hours and still work effectively.

  • Donor/recipient pairs do not meet until after the exchange has taken place and only if each person agrees.

Non-Directed Donation

Non-directed donors are everyday people who decide to make a difference in the life of a stranger by donating a kidney. When connected with incompatible, existing donor/recipient pairs, non-directed donors start a domino effect of kidney donations. The combination of non-directed donation and living donation can significantly lower the number of patients on the transplant waiting list.


“Becoming a living kidney donor is a serious decision, with some risks, but many rewards. I couldn't get past the idea that the slim chance that this surgery might affect my quality of life was more than offset by the knowledge that my kidney might mean all the difference to some child who would have no life at all if I backed away.”

- John Temple, non-directed kidney donor


The Kidney Transplant Program

Contact us for more information about the kidney transplant program.


The Johns Hopkins Kidney Transplant Program

Our comprehensive center provides advanced treatment for kidney care, learn more about our programs.

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