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

When an acute hemolytic transfusion reaction is suspected, the blood bag with all attached tubing and a new post-transfusion sample must be returned to the blood bank immediately. This allows comparison of pre- and post-transfusion specimens, visual inspection for hemolysis, and repeat compatibility testing—the foundational steps of a transfusion reaction workup.

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

An antibody with an apparent anti-E pattern in an E-positive patient cannot be a true alloanti-E (patients do not make alloantibodies to antigens they express). The pattern may represent an autoantibody with E-like specificity or a mimicking alloantibody. Adsorption studies and additional panel work are required to clarify specificity before antigen-negative blood is selected.

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

Anti-Lea is typically IgM, reacts best at room temperature, does not react at 37°C or AHG phase, and is considered clinically insignificant because it does not cause hemolytic transfusion reactions at physiologic temperature. Standard practice is to document the antibody and provide ABO/Rh-compatible blood without the requirement for Lea-negative units.

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

Post-bone marrow transplant patients often show mixed-field agglutination due to chimerism—a coexisting population of recipient (group A) and donor (group O) red cells in circulation during engraftment. This is expected and should be correlated with the transplant history rather than attributed to a subgroup or reagent failure.

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

Massive transfusion with packed red blood cells (which contain no coagulation factors or platelets) dilutes the patient's clotting factors and fibrinogen. A prolonged PT and aPTT combined with a critically low fibrinogen (<100 mg/dL) are hallmarks of dilutional coagulopathy and indicate the need for fresh frozen plasma, cryoprecipitate, and platelets.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

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