CSMLS Transfusion Science Principles Questions and Answers

Question 1

An ABO discrepancy is observed in a 75-year-old patient. The forward grouping shows Anti-A: 4+, Anti-B: 0. The reverse grouping shows A1 cells: 0, B cells: 1+. An autocontrol is negative. What is the most probable cause of this discrepancy?

Accepted Answer

Age-related decrease in anti-B antibody production

Answer

The forward type is clearly Group A. The reverse grouping confirms the absence of anti-A but shows a weak (1+) reaction with B cells. In elderly patients, it is common for isoagglutinin (antibody) titres, such as anti-B, to decrease, leading to weak or missing reactions in the reverse group. The negative autocontrol makes a cold autoantibody less likely.

Question 2

A bone marrow transplant recipient requires a red blood cell transfusion. To prevent Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD), which of the following component modifications is most critical?

Accepted Answer

Irradiated

Answer

Irradiation is the only method that inactivates donor T-lymphocytes, which are responsible for causing TA-GVHD in severely immunocompromised recipients, such as bone marrow transplant patients. While leukoreduction removes most white cells and CMV-seronegative units prevent cytomegalovirus transmission, they do not reliably prevent TA-GVHD.

Question 3

Fifteen minutes into a red blood cell transfusion, a patient develops fever, chills, hypotension, and reports red-coloured urine. The post-transfusion direct antiglobulin test (DAT) is positive. What is the most likely type of transfusion reaction?

Accepted Answer

Acute Hemolytic Transfusion Reaction (AHTR)

Answer

The combination of fever, chills, hypotension, hemoglobinuria (red urine), and a positive DAT strongly indicates an Acute Hemolytic Transfusion Reaction. This is a medical emergency caused by the rapid destruction of donor red blood cells by recipient antibodies, most often due to ABO incompatibility.

Question 4

An RhD-negative mother has just delivered an RhD-positive infant. The mother's antibody screen is negative. According to Canadian guidelines, what is the primary purpose of administering Rh Immune Globulin (RhIG) to the mother within 72 hours?

Accepted Answer

To prevent the mother from forming anti-D that could affect future RhD-positive pregnancies

Answer

Postpartum RhIG provides passive anti-D to the mother. This passive antibody binds to and clears any RhD-positive fetal red cells that may have entered her circulation during delivery, preventing her immune system from recognizing the D antigen and becoming actively immunized. This protects future RhD-positive fetuses from Hemolytic Disease of the Fetus and Newborn.

Question 5

A patient has a history of a clinically significant antibody, anti-K, but their current antibody screen is negative. Which of the following is the most appropriate crossmatch procedure to ensure safety?

Accepted Answer

A full antiglobulin (IAT) crossmatch using K-antigen negative donor units.

Answer

A history of a clinically significant antibody is critical information. Even if the antibody is currently undetectable, the patient could have an anamnestic response upon re-exposure. Therefore, antigen-negative units must be selected, and a full antiglobulin (IAT) crossmatch must be performed to ensure serological compatibility and detect any low-titer antibodies.

CSMLS - Canadian Society for Medical Laboratory Science Practice Test

CSMLS - Canadian Society for Medical Laboratory Science Practice Test

CSMLS Transfusion Science Principles Questions and Answers