Nationally, there are over 53,000 patients waiting for a kidney or kidney-pancreas transplant.

Policy 3.5 Organ Distribution

3.5 Allocation Of Cadaveric Kidneys. Cadaveric kidneys must be allocated according to the following policies. The final decision to accept a particular organ will remain the prerogative of the transplant surgeon and/or physician responsible for the care of the patient. This allows physicians and surgeons to exercise their medical judgment regarding the suitability of the organ being offered for a specific patient; to be faithful to their personal and programmatic philosophy about such controversial matters as the importance of cold ischemia time and anatomic anomalies; and to give their best assessment of the prospective recipient's medical condition at the moment. If an organ is declined for a patient, a notation of the reason for that decision must be made on the appropriate form and submitted promptly to UNOS.

3.5.1 ABO "O" Kidneys into ABO "O" Recipients and ABO "B" Kidneys into ABO "B" Recipients. Blood type O kidneys must be transplanted only into blood type O patients except in the case of zero antigen mismatched patients (as defined in Policy 3.5.2.1) who have a blood type other than O. Additionally, blood type B kidneys must be transplanted only into blood type B patients except in the case of zero antigen mismatched patients (as defined in Policy 3.5.2.1) who have a blood type other than B. Therefore, kidneys from a blood type O donor are to be allocated only to blood type O patients, and kidneys from a blood type B donor are to be allocated only to blood type B patients, with the exception for zero antigen mismatched patients noted above. This policy, however, does not nullify the physician's responsibility to use appropriate medical judgment in an extreme circumstance.

NOTE: The amendments to Policy 3.5.1 (ABO "O" Kidneys into ABO "O" Recipients and ABO "B" Kidneys into ABO "B" Recipients) shall be implemented following programming modifications to the UNOS computer system.

3.5.2Mandatory Sharing of Zero Antigen Mismatched Kidneys. The following policies apply to allocation of any cadaveric kidney for which there is a patient on the UNOS Patient Waiting List with a zero antigen mismatch:

3.5.2.1Definition. A zero antigen mismatch is defined as occurring when a patient on the UNOS Waiting List has an ABO blood type that is compatible with that of the donor and the patient and donor both have all six of the same HLA-A, B, and DR antigens. A zero antigen mismatch is also defined as a match occurring when there is phenotypic identity between the donor and recipient with regard to HLA, A, B, and DR antigens when at least one antigen is identified at each locus. Phenotypic identity means that the donor and patient each has the same antigens identified at each pair of A, B, and DR HLA loci. Patients with only one antigen identified at an HLA locus (A, B, or DR) are presumed "homozygous" at that locus (i.e. homologous chromosomes are presumed to code for identical antigens at that locus). For example, a donor or patient typed as A2,A-(blank) would be considered A2,A2. A zero antigen mismatch would also include cases where both antigens are identified at a locus in the patient but the donor is typed as being homozygous for one of the patient's antigens at that locus. For example, there would be a zero antigen mismatch if the recipient were typed as A1, A31, B8, B14, DR3, DR4 and the donor were typed as A1.A- (blank), B8, B14. DR3, DR-(blank). If the donor is homozygous at any A, B, or DR locus, the match can be said to be a zero antigen mismatch, as long as none of the identified A, B, or DR donor antigens are different from those of the recipient.

3.5.2.2 Computer Entry. Information regarding each and every cadaveric kidney donor must be entered into the UNOS computer system prior to kidney allocation, to determine whether there is a zero antigen mismatch between the donor and any patient on the UNOS Patient Waiting List.

3.5.2.3 Mandatory Sharing. With the exception of cadaveric kidneys procured for simultaneous kidney and non-renal organ transplantation as described in Policy 3.5.2.4, if there is any patient on the UNOS Patient Waiting List for whom there is a zero antigen mismatch with a donor, the kidney(s) from that donor shall be offered to the appropriate UNOS member for the patient with the zero antigen mismatch subject to time limitations for such organ offers set forth in Policy 3.5.2.5. If both donor kidneys are transplantable, the recipient center that was offered the kidney for a patient with a zero antigen mismatch does not have the implicit right to choose between the two kidneys. The final decision as to which of the two kidneys is to be shared rests with the Host OPO. In lieu of the four additional points for a patient with a PRA of 80% or higher and a preliminary negative crossmatch (Policy 3.5.9.3) four additional points will be added to all patients for whom there is a zero antigen mismatch and whose PRA is 80% or higher regardless of preliminary crossmatch results. When multiple zero antigen mismatches are found for a single donor, the allocation will be in the following sequence: