CMT Blood Banking and Transfusion Medicine Flashcards

A Kleihauer-Betke test shows 1.2% fetal cells in an Rh-negative mother with an estimated 5,000 mL blood volume. Using standard rounding rules, how many 300 µg RhIG vials are indicated?

Answer: 3 vials

Fetal bleed = 1.2 x 50 = 60 mL whole blood; 60/30 = 2.0, rounded down to 2, plus 1 extra vial = 3 vials.

An antibody panel shows stronger reactions after the panel cells are treated with ficin. Which antibody is most likely present?

Answer: Anti-Jka

Kidd antigens resist proteolytic enzymes and Kidd reactivity is enhanced, while Duffy, M, N, and S antigens are destroyed by ficin.

What is the main transfusion risk linked to storing platelets at 20-24°C?

Answer: Bacterial contamination

Room-temperature storage lets bacteria grow, so platelets have the highest bacterial contamination risk of all components.

Within minutes of starting a plasma transfusion, a patient develops hypotension, bronchospasm, and urticaria. Testing shows IgA deficiency with anti-IgA. Which products are best for future transfusions?

Answer: Products from IgA-deficient donors or washed cellular products

Anaphylaxis from anti-IgA is prevented by giving IgA-deficient donor products or washed cellular components that remove plasma IgA.

Which coagulation factor is NOT present in clinically significant amounts in cryoprecipitate?

Answer: Factor IX

Cryoprecipitate has fibrinogen, FVIII, vWF, FXIII, and fibronectin, but not factor IX.

A patient on high-dose IV penicillin has a positive IgG DAT. The eluate reacts only with penicillin-coated red cells. Which mechanism explains this?

Answer: Drug adsorption (hapten)

Penicillin binds firmly to the RBC membrane, and the antibody against the drug reacts only with drug-coated cells.

A unit of red blood cells with 30 days left before its original expiration date is irradiated today. What is its new expiration?

Answer: 28 days from irradiation

Irradiated RBCs expire 28 days after irradiation or on the original date, whichever comes first.