ASCP Transfusion Medicine 3

Question 1

Massive transfusion protocol (MTP) typically uses a ratio of plasma:platelets:red blood cells of approximately:

Accepted Answer

1:1:1

Answer

Modern MTPs use a 1:1:1 ratio of FFP:apheresis platelets:PRBCs. This damage control resuscitation strategy minimizes dilutional coagulopathy and improves survival in massive hemorrhage.

Question 2

The most common immune cause of platelet refractoriness is:

Accepted Answer

HLA alloimmunization (anti-HLA class I antibodies)

Answer

HLA class I alloimmunization (from prior transfusions, pregnancies, or transplants) is the most common immune cause of platelet refractoriness. HLA-matched or crossmatch-compatible platelets are required for refractory patients.

Question 3

A patient with a history of heparin-induced thrombocytopenia (HIT) requires cardiac surgery. The most appropriate anticoagulant approach is:

Accepted Answer

Use bivalirudin (direct thrombin inhibitor) or delay until PF4-heparin antibodies decline

Answer

HIT is caused by IgG antibodies against PF4-heparin complexes, causing thrombocytopenia and paradoxical thrombosis. LMWH cross-reacts with HIT antibodies and is contraindicated. Bivalirudin is the preferred alternative anticoagulant for cardiac surgery in HIT patients.

Question 4

Neonatal alloimmune thrombocytopenia (NAIT) most commonly involves antibodies against which platelet antigen?

Accepted Answer

Human platelet antigen 1a (HPA-1a)

Answer

NAIT is most commonly (more than 80% of cases) caused by maternal IgG antibodies against HPA-1a (also called PL-A1 or Zw-a), a platelet-specific antigen on glycoprotein IIIa (CD61). HPA-1a negative mothers (2–3% of Caucasians) may form anti-HPA-1a when exposed to HPA-1a-positive fetal platelets.

Question 5

Gel (column agglutination) technology in blood banking works by:

Accepted Answer

Centrifuging red cells through a gel matrix — agglutinated cells are trapped at the top while unagglutinated cells pellet at the bottom

Answer

Gel cards contain microtubes filled with dextran acrylamide gel with or without antiglobulin reagent. During centrifugation, unagglutinated cells pass through the gel and pellet at the bottom (negative result). Agglutinated cells are trapped in or at the top of the gel column (positive result).

ASCP Practice Test

ASCP Practice Test

ASCP Transfusion Medicine 3