ASCP Transfusion Medicine

Question 1

Which ABO blood group is considered the 'universal donor' for red blood cell transfusions?

Accepted Answer

Group O

Answer

Group O red cells lack A and B antigens, so they will not trigger an ABO incompatibility reaction in A, B, or AB recipients. Group O negative is the universal donor for red cells as it also lacks the D antigen.

Question 2

The indirect antiglobulin test (IAT or indirect Coombs test) detects:

Accepted Answer

Unexpected antibodies in patient serum that react with reagent red cells in vitro

Answer

IAT detects unexpected alloantibodies or autoantibodies in patient serum or plasma by incubating patient serum with reagent red cells, washing to remove unbound antibody, then adding anti-human globulin (AHG) reagent that agglutinates IgG-coated cells.

Question 3

Hemolytic disease of the fetus and newborn (HDFN) caused by anti-D requires all of the following EXCEPT:

Accepted Answer

ABO incompatibility between mother and fetus

Answer

ABO incompatibility between mother and fetus does NOT cause Rh HDFN — it actually may reduce the risk by rapidly clearing fetal cells from maternal circulation before alloimmunization can occur. HDFN requires D-negative mother, D-positive fetus, and maternal IgG anti-D.

Question 4

Which blood product is most appropriate for a patient with isolated thrombocytopenia (platelet count 15,000/µL) and active bleeding?

Accepted Answer

Apheresis platelets (single donor)

Answer

Apheresis (single-donor) platelets are the product of choice for thrombocytopenic bleeding. One apheresis unit contains at least 3.0 times 10 to the 11th platelets (equivalent to 4–6 random donor units) and raises platelet count by approximately 30,000–50,000/µL.

Question 5

A positive direct antiglobulin test (DAT) combined with a positive elution study suggests:

Accepted Answer

Warm autoimmune hemolytic anemia (WAIHA) or alloantibody causing hemolysis

Answer

Positive DAT means IgG and/or complement is coating the patient's red cells in vivo. Elution removes and identifies the antibody. If the eluate is reactive with antigen-positive cells, it confirms an antibody causing in vivo sensitization consistent with WAIHA or alloantibody from hemolytic transfusion reaction.

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ASCP Transfusion Medicine