CHT Organ & Tissue Allocation 2 — Questions and Answers
Question 1: What is a 'zero-antigen mismatch' kidney in UNOS allocation policy?
- A kidney with no mismatches at HLA-A, -B, and -DR compared to the recipient (Correct answer)
- A kidney from an HLA-identical sibling donor
- A kidney with no detectable donor antigens on its surface
- A kidney matched only at blood group with no HLA typing done
Correct answer: A kidney with no mismatches at HLA-A, -B, and -DR compared to the recipient
Zero-antigen mismatch (0-MM) kidneys have no mismatches at HLA-A, -B, and -DR antigens between donor and recipient and are shared nationally under UNOS policy due to superior outcomes.
Question 2: Which organ has the shortest clinically acceptable cold ischemia time, requiring the fastest allocation decisions?
- Heart (Correct answer)
- Kidney
- Liver
- Pancreas
Correct answer: Heart
Hearts have a cold ischemia tolerance of only 4–6 hours, requiring rapid allocation and transportation to minimize ischemic injury.
Question 3: In the context of living donor kidney transplantation, what is a 'paired kidney exchange' program?
- Incompatible donor-recipient pairs swap donors with other incompatible pairs to create compatible matches (Correct answer)
- A program where one donor provides a kidney to two recipients simultaneously
- Living donors are paired with deceased donors for double transplantation
- Recipients swap waiting list positions with compatible living donor pairs
Correct answer: Incompatible donor-recipient pairs swap donors with other incompatible pairs to create compatible matches
Kidney paired donation matches incompatible living donor-recipient pairs with other pairs so that each donor gives to a compatible recipient from another pair.
Question 4: What does 'cold ischemia time' refer to in organ transplantation?
- The time from organ cooling/flushing at procurement until the clamp is removed and blood flow is restored in the recipient (Correct answer)
- The total time from donor death to transplant surgery
- The duration of hypothermic machine perfusion only
- The time the organ spends at room temperature during transport
Correct answer: The time from organ cooling/flushing at procurement until the clamp is removed and blood flow is restored in the recipient
Cold ischemia time begins when the organ is flushed with cold preservation solution and ends at reperfusion in the recipient, representing the total ischemic insult during hypothermic storage.
Question 5: Which US law established the framework for organ transplantation, prohibited organ sales, and created the OPTN?
- National Organ Transplant Act (NOTA) of 1984 (Correct answer)
- Uniform Determination of Death Act (UDDA) of 1981
- Health Insurance Portability and Accountability Act (HIPAA) of 1996
- Americans with Disabilities Act (ADA) of 1990
Correct answer: National Organ Transplant Act (NOTA) of 1984
NOTA established the legal framework for transplantation in the US, created the OPTN, prohibited the sale of organs, and mandated equitable organ sharing.
Question 6: What is the primary purpose of HLA typing in the context of deceased donor organ allocation?
- To identify compatible recipients, perform virtual crossmatches, and prioritize zero-mismatch candidates (Correct answer)
- To diagnose the cause of brain death in the donor
- To determine ABO blood type for compatibility
- To assess donor organ quality before procurement
Correct answer: To identify compatible recipients, perform virtual crossmatches, and prioritize zero-mismatch candidates
Rapid deceased donor HLA typing allows the allocation center to identify compatible candidates, perform virtual crossmatches, flag DSA concerns, and apply zero-mismatch priority rules.
CHT Organ & Tissue Allocation 2
What is a 'zero-antigen mismatch' kidney in UNOS allocation policy?