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Organ Type and Waiting Time

Most candidates, except those with living donors, wait for an organ due to the shortage of donor organs. Because each candidate's situation is unique, waiting times can vary, depending on a number of factors, such as those described below. To better understand what influences waiting time, talk with your transplant team.

What determines who will be offered an organ?

Depending on the organ, there are many considerations. These include but are not limited to:

  • age
  • blood type
  • medical urgency
  • waiting time
  • geographic distance between donor and recipient
  • size of the donor organ in relation to the recipient
  • type of organ needed

How does organ type affect waiting times?

Heart Allocation

Physicians assign a status code to individuals waiting for a heart transplant. This code indicates how medically urgent it is that you receive a transplant. In addition, the system allocates hearts locally first, and then in a specific sequence by zone. Please see the OPTN/UNOS Allocation of Thoracic Organs Policy for details.

Lung Allocation

All candidates waiting for a lung will be grouped together, regardless of whether they are waiting for a single lung or a double lung. If one lung is allocated to a patient needing a single lung transplant, the other lung will be then allocated to another patient waiting for a single lung transplant. In addition, the system allocates thoracic organs locally first, and then in a specific sequence by zone. Please see the OPTN/UNOS Allocation of Thoracic Organs Policy for details.

Heart/Lung Allocation

If you are waiting for heart-lung transplant, you will be registered on the individual UNOS Patient Waiting lists for both the heart and the lung. When the patient is eligible to receive a heart, the lung will be allocated to the heart-lung candidate from the same donor. When the patient is eligible to receive a lung, the heart shall be allocated to the heart-lung candidate from the same donor isolated. In addition, thoracic organs are allocated locally first, and then in a specific sequence by zone. Please see the OPTN/UNOS Allocation of Thoracic Organs Policy for details.

Liver Allocation

If you are waiting for a liver transplant, your physician will give you a status code.This code indicates your mortality risk score or degree of medical urgency, referred to as your MELD/PELD scores (The Model for End-Stage Liver Disease/Pediatric End-Stage Liver Disease). The system offers liver to candidates with the highest MELD/PELD scores first. Geographic factors are also taken into consideration. Please see the OPTN/UNOS Allocation of Livers Policy for details.

Kidney Allocation

The current kidney allocation policy considers characteristics of both the donor and the transplant candidate in allocating kidneys equally, efficiently and effectively. A combination of factors, working together, determines who receives which organ. These factors include tissue match between donor and candidate; blood type; blood antibody levels; length of time spent on the waiting list; whether the potential organ candidate is a child; body size of both donor and candidate; and geographic factors. Please see the OPTN/UNOS Allocation of Deceased Kidneys Policy for details.

Pancreas Allocation

In general, pancreases are allocated locally first, then regionally and nationally based on certain geographic zones. For local pancreas allocation, recipients may be selected from candidates awaiting an isolated pancreas, kidney-pancreas combination, or a combined solid organ-islet transplant from the same donor. Please see the OPTN/UNOS Allocation of Pancreas Policy for details.




This Web site is intended solely for the purpose of electronically providing the public with general health-related information and convenient access to the data resources. UNOS is not affiliated with any one product nor does UNOS assume responsibility for any error, omissions or other discrepancies.

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