Medical Laboratory Technician Exam Blood Bank and Transfusion 3 — Questions and Answers
Question 1: Which test detects weak subgroups of A (A3, Ax) that are missed by routine ABO typing?
- Lectin Ulex europaeus
- Lectin Dolichos biflorus
- Anti-H lectin
- Adsorption-elution technique (Correct answer)
Correct answer: Adsorption-elution technique
Adsorption-elution concentrates anti-A onto cells with very few A antigens, allowing confirmation of weak A subgroups not detected by direct agglutination.
Question 2: Cold agglutinin disease is most commonly caused by antibodies of which specificity?
- Anti-P1
- Anti-M
- Anti-I (Correct answer)
- Anti-Le(a)
Correct answer: Anti-I
Anti-I is the specificity of the monoclonal IgM cold agglutinin produced in cold agglutinin disease, reacting optimally at 0–4°C.
Question 3: Which preservative solution allows red blood cells to be stored for up to 42 days?
- ACD-A
- CPD
- CPDA-1
- AS-1 (Adsol) (Correct answer)
Correct answer: AS-1 (Adsol)
Additive solutions such as AS-1 (Adsol) extend RBC shelf life to 42 days by providing extra nutrients for RBC metabolism.
Question 4: A unit of FFP is thawed at 37°C and must be transfused within:
- 4 hours if kept at room temperature
- 24 hours if kept at 1–6°C (Correct answer)
- 5 days if refrozen immediately
- 72 hours at room temperature
Correct answer: 24 hours if kept at 1–6°C
Thawed FFP relabeled as 'thawed plasma' can be stored at 1–6°C for up to 5 days; if used as FFP it should be infused within 24 hours.
Question 5: The Kidd blood group system is clinically significant primarily because Kidd antibodies:
- Are always IgM and fix complement
- Cause dosage and are often transient, leading to delayed hemolytic reactions (Correct answer)
- React only at room temperature
- Are neutralized by soluble antigen in plasma
Correct answer: Cause dosage and are often transient, leading to delayed hemolytic reactions
Kidd antibodies show dosage, fall below detectable levels quickly, and can cause severe delayed hemolytic transfusion reactions when the antigen is re-encountered.
Question 6: Which blood component is the treatment of choice for isolated factor VIII deficiency (Hemophilia A)?
- Fresh Frozen Plasma
- Cryoprecipitate
- Factor VIII concentrate (Correct answer)
- Platelet concentrate
Correct answer: Factor VIII concentrate
Recombinant or plasma-derived Factor VIII concentrate is the preferred treatment for Hemophilia A due to its purity, safety, and precise dosing.
Question 7: In the indirect antiglobulin test (IAT), what step follows incubation of patient serum with reagent red cells?
- Addition of Coombs serum immediately
- Three washes with saline followed by addition of AHG (Correct answer)
- Reading for hemolysis under UV light
- Addition of LISS and re-incubation for 60 minutes
Correct answer: Three washes with saline followed by addition of AHG
Washing three times with saline removes unbound immunoglobulin; residual unbound IgG would neutralize AHG and cause a false-negative result.
Medical Laboratory Technician Exam Blood Bank and Transfusion 3
Which test detects weak subgroups of A (A3, Ax) that are missed by routine ABO typing?