Medical Laboratory Technician Exam Blood Bank and Transfusion 5 — Questions and Answers
Question 1: Which blood group system is associated with the receptor for Plasmodium vivax malaria?
- Duffy (Fy) (Correct answer)
- Kidd (Jk)
- MNS
- Diego (Di)
Correct answer: Duffy (Fy)
The Duffy antigen (DARC) is the receptor for P. vivax merozoites; Fy(a-b-) individuals, common in West Africa, are resistant to P. vivax malaria.
Question 2: A technologist performing an elution notices the eluate reacts with all panel cells. The MOST likely cause is:
- A cold autoantibody
- A warm autoantibody coating the red cells (Correct answer)
- An alloantibody to a high-frequency antigen
- ABO incompatibility
Correct answer: A warm autoantibody coating the red cells
A panreactive eluate is classic for warm autoimmune hemolytic anemia (WAIHA), where autoantibody eluted from the patient's cells reacts with all test cells.
Question 3: According to AABB Standards, the minimum hemoglobin content in a unit of packed red blood cells must be at least:
- 45 g per unit
- 51 g per unit (Correct answer)
- 60 g per unit
- 70 g per unit
Correct answer: 51 g per unit
AABB Standards require ≥51 g of hemoglobin per RBC unit (≥80% of units tested) to ensure adequate therapeutic content.
Question 4: Which blood group antibody is classically associated with paroxysmal cold hemoglobinuria (PCH)?
- Anti-I
- Anti-P (Donath-Landsteiner antibody) (Correct answer)
- Anti-Le(a)
- Anti-M
Correct answer: Anti-P (Donath-Landsteiner antibody)
PCH is caused by the Donath-Landsteiner biphasic antibody, which has anti-P specificity, binding complement at cold temperatures and causing hemolysis upon warming.
Question 5: Massive transfusion is generally defined as transfusion of:
- More than 2 units of RBCs in 24 hours
- More than 5 units of FFP
- 10 or more units of RBCs within 24 hours (or one blood volume) (Correct answer)
- Any transfusion requiring platelet support
Correct answer: 10 or more units of RBCs within 24 hours (or one blood volume)
Massive transfusion is defined as replacement of one entire blood volume (approximately 10 units of RBCs) within 24 hours in an adult.
Question 6: A sample with a mixed-field agglutination pattern in ABO forward grouping is MOST consistent with:
- A1B subgroup
- Recent ABO-incompatible stem cell transplant (Correct answer)
- Cold autoantibody
- Anti-A,B cross-reaction
Correct answer: Recent ABO-incompatible stem cell transplant
Mixed-field agglutination reflects two populations of red cells (donor and recipient), as seen after ABO-mismatched hematopoietic stem cell transplantation.
Question 7: Which additive is included in CPDA-1 anticoagulant-preservative solution to extend RBC shelf life beyond CPD?
- Mannitol
- Adenine (Correct answer)
- Sodium chloride
- Phosphate buffer only
Correct answer: Adenine
Adenine in CPDA-1 supports ATP synthesis in stored RBCs, extending viability from 21 days (CPD) to 35 days.
Medical Laboratory Technician Exam Blood Bank and Transfusion 5
Which blood group system is associated with the receptor for Plasmodium vivax malaria?