Expert Immunohematology Assessment – 10 MCQs | Kenya MBChB

Q1: A patient with a known anti-Jk(a) antibody requires an urgent transfusion. The current antibody screen is negative. What is the most appropriate next step to ensure a safe transfusion?

1. A. Provide Jk(a) negative units even if the crossmatch is compatible.
2. B. Provide crossmatch-compatible units regardless of Jk(a) status.
3. C. Perform an elution on the patient's pre-transfusion sample.
4. D. Administer intravenous immunoglobulin (IVIG) prior to transfusion.

Correct answer: A – Provide Jk(a) negative units even if the crossmatch is compatible.

Kidd antibodies can become undetectable over time, but the patient remains sensitized. A historic antibody must always be respected — always provide antigen-negative units regardless of current screen results.

Q2: In a patient with warm autoimmune hemolytic anemia (WAIH

1. A. and a pan-reactive antibody screen, which method is used to detect underlying alloantibodies if the patient has been transfused in the last 3 months?
2. B. Autologous adsorption
3. C. Allogeneic adsorption using phenotype-matched cells
4. D. Acid elution
5. E. Saline replacement technique

Correct answer: C – Allogeneic adsorption using phenotype-matched cells

Autologous adsorption can't be used in recently transfused patients (donor cells would adsorb the alloantibody too). Allogeneic adsorption with phenotype-matched cells removes the autoantibody while preserving detectable alloantibodies.

Q3: Which blood group system is most frequently associated with delayed hemolytic transfusion reactions that present with a rapid drop in hemoglobin but negative initial antibody screens?

1. A. Kell
2. B. Duffy
3. C. MNS
4. D. Kidd

Correct answer: D – Kidd

The Kidd system is the classic cause of delayed hemolytic transfusion reactions. Antibodies fade quickly, screen negative, then surge after re-exposure causing rapid intravascular hemolysis.

Q4: A 32-year-old female experiences severe hypotension and bronchospasm within minutes of starting a red cell transfusion. She has a history of recurrent respiratory infections. What is the most likely underlying deficiency?

1. A. Haptoglobin deficiency
2. B. Selective IgA deficiency
3. C. C1 esterase inhibitor deficiency
4. D. Albumin deficiency

Correct answer: B – Selective IgA deficiency

IgA-deficient patients can develop anti-IgA antibodies. Transfusion of blood products containing IgA triggers a severe anaphylactic reaction. Recurrent infections are a clue to the underlying immunodeficiency.

Q5: Which specific modification to blood products is required to prevent Transfusion-Associated Graft-versus-Host Disease (TA-GvH

1. A. in an immunocompromised bone marrow transplant recipient?
2. B. Leukoreduction
3. C. Irradiation
4. D. Washing with saline
5. E. Volume reduction

Correct answer: A – in an immunocompromised bone marrow transplant recipient?

Q6: During a massive transfusion protocol, a patient develops ionized hypocalcemia. This is most likely a direct metabolic consequence of which preservative/anticoagulant used in blood storage?

1. A. Heparin
2. B. Sodium Citrate
3. C. Adenine
4. D. Dextrose

Correct answer: B – Sodium Citrate

Sodium citrate is used as an anticoagulant in blood storage. It chelates (binds) free ionized calcium, causing hypocalcemia during massive transfusion when large volumes are infused rapidly.

Q7: A neonate requires an exchange transfusion for HDFN caused by anti-c. The mother is O positive, R1R1 (CDe/CDe). The infant is A positive, R1r (CDe/ce). What is the most appropriate blood type for the exchange?

1. A. O positive, c-negative (R1R1) RBCs
2. B. A positive, c-negative (R1R1) RBCs
3. C. O positive, c-positive (rr) RBCs
4. D. AB positive, c-negative (R1R1) RBCs

Correct answer: A – O positive, c-negative (R1R1) RBCs

Blood must be c-negative to avoid destruction by maternal anti-c still circulating in the neonate. O type is chosen over A to be compatible with any residual maternal ABO antibodies. c-negative (R1R1) is essential.

Q8: TRALI is most commonly caused by antibodies in the donor plasma directed against which of the following in the recipient?

1. A. Red cell antigens
2. B. Platelet glycoproteins
3. C. HLA or Human Neutrophil Antigens (HN
4. D. Plasma proteins like albumin

Correct answer: C – HLA or Human Neutrophil Antigens (HN

Donor anti-HLA or anti-HNA antibodies bind to recipient neutrophils, activating them in the pulmonary vasculature and causing the capillary leak that defines TRALI (acute lung injury within 6 hours of transfusion).

Q9: What is the shelf life of a unit of Red Blood Cells that has been 'opened' by entering the system for washing or aliquoting in an open system, if stored at 1-6°C?

1. A. 4 hours
2. B. 24 hours
3. C. 7 days
4. D. 42 days

Correct answer: A – 4 hours

Q10: A patient is found to have the 'Bombay' phenotype (Oh). Which of the following statements regarding their transfusion needs is correct?

1. A. They can safely receive Type O negative blood.
2. B. They can only receive blood from another Bombay phenotype donor.
3. C. They can receive any Rh-negative blood.
4. D. They require H-substance neutralized plasma.

Correct answer: B – They can only receive blood from another Bombay phenotype donor.

Bombay phenotype patients lack H antigen entirely and have anti-H, anti-A, and anti-B antibodies. They will hemolyze all standard blood including O negative. Only another Bombay phenotype donor is compatible.