Medical Laboratory Technician Exam Medical Laboratory Technician Blood Banking and Transfusion 1

Question 1

A patient receiving a red blood cell transfusion develops fever, chills, and hypotension 30 minutes into the infusion.
The post-transfusion plasma appears pink.
Which action should the technologist perform FIRST after the transfusion is stopped?

Accepted Answer

Return the blood bag and all attached tubing to the blood bank with a new post-transfusion blood sample

Answer

Perform a direct antiglobulin test (DAT) on the pre-transfusion sample

Answer

Issue O-negative blood for an emergency transfusion

Answer

Repeat the ABO typing on the original donor unit

Question 2

An antibody identification panel shows reactivity in a pattern consistent with anti-E. Before reporting, the technologist should confirm the patient's phenotype for the E antigen. If the patient is E-positive, what is the most appropriate interpretation?

Accepted Answer

The antibody may be an autoantibody or a mimicking alloantibody; additional testing is required

Answer

The anti-E is a clinically insignificant cold-reactive antibody

Answer

The result is likely due to a rouleaux artifact; saline replacement should be performed

Answer

The antibody is probably an alloantibody directed against a high-frequency antigen

Question 3

A group A, Rh-positive patient has an unexpected positive antibody screen. The technologist performs an antibody identification panel and finds reactivity only with cells expressing the Lea antigen. The reaction strength is 1+ at immediate spin and is not enhanced at 37°C or AHG phase. What is the most appropriate course of action?

Accepted Answer

Document anti-Lea as a clinically insignificant cold-reactive antibody and provide ABO/Rh-compatible blood

Answer

Provide Lea-negative, crossmatch-compatible blood for all future transfusions

Answer

Report anti-Lea as a clinically significant antibody requiring antigen-negative blood

Answer

Perform a warm autoadsorption before proceeding with antigen-negative selection

Question 4

During pretransfusion testing, a technologist detects a mixed-field agglutination pattern when testing a patient's cells with anti-A serum. The patient's medical history notes a recent bone marrow transplant from a group O donor. What is the most likely explanation?

Accepted Answer

Engraftment of donor O cells is producing a mixed population of A and O red cells

Answer

The patient has a weak A subgroup such as A3

Answer

The mixed-field pattern indicates a positive DAT

Answer

The reagent anti-A has deteriorated and should be replaced

Question 5

A massive transfusion protocol is activated for a trauma patient. After receiving 12 units of packed red blood cells, the patient develops prolonged bleeding from IV sites. Which laboratory finding best supports transfusion-associated dilutional coagulopathy?

Accepted Answer

Prolonged PT and aPTT with a fibrinogen level of 80 mg/dL

Answer

Platelet count of 180,000/µL and PT within normal limits

Answer

Elevated fibrinogen and shortened thrombin time

Answer

Hemoglobin of 7 g/dL with normal coagulation studies

Question 6

A technologist is performing a weak D (Du) test on a sample typed as Rh-negative by the immediate spin method. The indirect antiglobulin test yields a 2+ reaction with anti-D. How should this result be interpreted, and what are the implications for this patient as a blood recipient?

Accepted Answer

The patient is weak D and should be classified as Rh-negative for transfusion purposes to prevent alloimmunization

Answer

The patient should be classified as Rh-positive and may receive Rh-positive blood without risk of anti-D formation

Answer

The result indicates a false positive due to inadequate washing; the test should be repeated

Answer

Weak D patients are always Rh-negative donors but can receive Rh-positive blood safely