Medical Laboratory TechnicianĀ Exam Blood Bank and Transfusion 4 ā Questions and Answers
Question 1: Granulocyte transfusions should be irradiated primarily to prevent:
- CMV transmission
- Febrile non-hemolytic transfusion reactions
- Transfusion-associated graft-versus-host disease (Correct answer)
- Alloimmunization to HLA antigens
Correct answer: Transfusion-associated graft-versus-host disease
Granulocyte components contain large numbers of T lymphocytes, making irradiation essential to prevent TA-GvHD.
Question 2: A patient types as group O with anti-A and anti-B but shows a weak forward reaction with anti-A,B reagent. The most likely explanation is:
- Acquired B antigen
- A subgroup such as Ax (Correct answer)
- Bombay phenotype
- Cold autoantibody interference
Correct answer: A subgroup such as Ax
Weak A subgroups (Ax, Aend) may not react with individual anti-A but can react with the cross-reacting anti-A,B reagent, revealing residual A antigen.
Question 3: When a transfusion reaction is suspected, which is the FIRST action the technologist should take?
- Centrifuge a post-transfusion specimen and inspect for hemolysis
- Stop the transfusion and notify the physician (Correct answer)
- Perform a DAT on the post-transfusion sample
- Repeat the ABO typing on the donor unit
Correct answer: Stop the transfusion and notify the physician
Stopping the transfusion immediately limits antigen-antibody exposure; clinical management by the physician follows simultaneously.
Question 4: Which coagulation factor is the ONLY one NOT found in cryoprecipitate?
- Factor VIII
- Fibrinogen
- Factor XIII
- Factor V (Correct answer)
Correct answer: Factor V
Cryoprecipitate is enriched in Factors VIII, XIII, fibrinogen, fibronectin, and vWF but does not contain Factor V in significant amounts.
Question 5: A patient has a positive DAT and a panreactive antibody panel. The most appropriate next step is to:
- Transfuse O-negative blood immediately without further workup
- Perform an autoadsorption to remove autoantibody before alloantibody identification (Correct answer)
- Repeat the panel using enzyme-treated cells
- Report no clinically significant antibody detected
Correct answer: Perform an autoadsorption to remove autoantibody before alloantibody identification
Autoadsorption removes warm autoantibody from the serum, allowing underlying alloantibodies to be detected before a potentially life-saving transfusion.
Question 6: The McLeod phenotype is associated with which clinical syndrome?
- Chronic granulomatous disease (Correct answer)
- Sickle cell disease
- Hereditary spherocytosis
- Paroxysmal nocturnal hemoglobinuria
Correct answer: Chronic granulomatous disease
The McLeod phenotype results from absence of the XK protein and is associated with X-linked chronic granulomatous disease and acanthocytic hemolytic anemia.
Question 7: Platelet refractoriness is best evaluated by calculating the:
- Percent reactive antibody (PRA)
- Corrected count increment (CCI) at 10ā60 minutes post-transfusion (Correct answer)
- Platelet aggregation ratio
- Bleeding time
Correct answer: Corrected count increment (CCI) at 10ā60 minutes post-transfusion
A CCI below 5,000 at 10ā60 minutes post-transfusion on two occasions indicates immune-mediated refractoriness; a low CCI at 24 hours suggests non-immune causes.
Medical Laboratory TechnicianĀ Exam Blood Bank and Transfusion 4
Granulocyte transfusions should be irradiated primarily to prevent: