MLPAO Transfusion Medicine Advanced Practice 1 — Questions and Answers
Question 1: What is an antibody panel and how is antibody identification performed?
- A single reagent red cell used to screen for all antibodies
- A set of 8-16 reagent red cell samples with known antigen profiles used to identify specific antibody specificity by the pattern of reactivity (Correct answer)
- A panel of patient sera tested against one red cell
- A list of all possible antibodies
Correct answer: A set of 8-16 reagent red cell samples with known antigen profiles used to identify specific antibody specificity by the pattern of reactivity
An antibody identification panel consists of group O reagent red cells (typically 10-16 cells) with known antigen phenotypes. Patient serum is tested against each panel cell, and the pattern of positive and negative reactions is compared to the antigen profile to identify the antibody specificity. Rule-out and rule-of-three criteria are applied.
Question 2: What is the rule of three in antibody identification?
- Three panel cells must be tested
- At least three antigen-positive cells must react and three antigen-negative cells must be non-reactive to confirm an antibody specificity (Correct answer)
- Three technologists must verify the result
- Three different methods must be used
Correct answer: At least three antigen-positive cells must react and three antigen-negative cells must be non-reactive to confirm an antibody specificity
The rule of three (p-value <0.05) requires at least three panel cells positive for the suspected antigen to show reactivity AND three panel cells negative for the suspected antigen to be non-reactive. This statistical requirement ensures that the antibody identification is not a chance association. Additional panel cells may be needed.
Question 3: What is autoabsorption and when is it used in the blood bank?
- Adding antibiotics to remove bacterial contamination
- Removing autoantibodies from patient serum using the patient's own red cells to unmask underlying alloantibodies (Correct answer)
- Absorbing all antibodies from serum
- Testing patient cells for autoantigens
Correct answer: Removing autoantibodies from patient serum using the patient's own red cells to unmask underlying alloantibodies
Autoabsorption is performed when a patient has warm autoantibodies (warm autoimmune hemolytic anemia) that react with all panel cells, making it impossible to detect underlying alloantibodies. Patient's own red cells (treated with enzymes to enhance adsorption) are incubated with the serum to remove autoantibody, and the absorbed serum is tested for alloantibodies.
Question 4: What are the Kidd blood group system antibodies known for in transfusion medicine?
- They are always clinically insignificant
- They frequently show dosage effect, can cause severe delayed hemolytic transfusion reactions, and are notorious for dropping to undetectable levels between exposures (Correct answer)
- They only cause mild reactions
- They are only found in neonates
Correct answer: They frequently show dosage effect, can cause severe delayed hemolytic transfusion reactions, and are notorious for dropping to undetectable levels between exposures
Kidd (Jk) antibodies are notoriously dangerous because: 1) They frequently drop to undetectable levels (evanescence), evading pre-transfusion antibody screening; 2) They rapidly produce an anamnestic response upon re-exposure; 3) They activate complement, causing severe intravascular hemolysis; 4) They show dosage (reacting stronger with homozygous cells).
Question 5: What is the electronic (computer) crossmatch and when can it be used?
- A crossmatch performed using electronic microscopy
- A computer-verified ABO compatibility check between patient and donor, used when the antibody screen is negative and the patient has no history of clinically significant antibodies (Correct answer)
- An automated serological crossmatch
- A virtual crossmatch using genetic data
Correct answer: A computer-verified ABO compatibility check between patient and donor, used when the antibody screen is negative and the patient has no history of clinically significant antibodies
The electronic crossmatch uses the laboratory information system to verify ABO compatibility between the patient and donor unit without serological testing. It requires: 1) Two concordant ABO/Rh typings on the patient, 2) Negative current antibody screen, 3) No history of clinically significant antibodies, 4) Validated computer system. It improves blood availability and reduces testing time.
Question 6: What is the significance of anti-K (anti-Kell) in prenatal testing?
- It is not significant in pregnancy
- Anti-K causes severe HDFN by both destroying fetal red cells and suppressing fetal erythropoiesis; monitoring differs from anti-D HDFN (Correct answer)
- Anti-K only affects the mother
- Anti-K is prevented by RhIg
Correct answer: Anti-K causes severe HDFN by both destroying fetal red cells and suppressing fetal erythropoiesis; monitoring differs from anti-D HDFN
Anti-K is the most significant non-Rh antibody in HDFN. Unlike anti-D, anti-K suppresses fetal erythropoiesis by targeting Kell antigen on erythroid progenitors, causing anemia without proportional hyperbilirubinemia. Middle cerebral artery Doppler peak systolic velocity (MCA-PSV) is used for fetal monitoring rather than amniotic fluid bilirubin.
MLPAO Transfusion Medicine Advanced Practice 1
What is an antibody panel and how is antibody identification performed?