Medical Laboratory Technician Blood Bank and Transfusion Questions and Answers

Question 1

A patient's antibody screen is positive. The antibody identification panel shows reactivity with all panel cells, and the auto-control is also positive. All reactions are occurring at the AHG phase. Which of the following is the MOST likely cause of these results?

Accepted Answer

A warm autoantibody

Answer

A warm autoantibody will react with the patient's own red cells (positive auto-control) and all reagent red cells used in the panel because they all possess the common antigens the autoantibody is directed against. The reactions are typically observed at the AHG (37°C) phase. A cold autoantibody typically reacts at room temperature or colder. Multiple alloantibodies would likely show a varying pattern of reactivity, and the auto-control would be negative. An antibody to a high-prevalence antigen would cause reactivity with all panel cells, but the auto-control would be negative.

Question 2

A unit of Red Blood Cells is issued from the blood bank at 08:00 for a routine transfusion. At 08:20, the nurse calls to report that the patient's IV has failed and the transfusion has not been started. The unit has been stored in a transport cooler with appropriate coolant packs. What is the correct course of action?

Accepted Answer

Return the unit to the blood bank immediately for proper storage.

Answer

According to AABB Standards, a blood component that has been issued but not transfused can be returned to the blood bank for reissue only if it has not been warmed above 10°C or cooled below 1°C during storage and transport. Since the unit was not spiked and was maintained at the correct temperature in a validated cooler, it can be immediately returned to the blood bank's monitored refrigerator. The 30-minute rule applies to units kept at room temperature without a validated cooling system.

Question 3

Which of the following blood components must be stored at 20-24°C with continuous, gentle agitation?

Accepted Answer

Platelets

Answer

Platelets must be stored at room temperature (20-24°C) with continuous gentle agitation to maintain their viability and prevent aggregation. Red Blood Cells are stored at 1-6°C. Fresh Frozen Plasma and Cryoprecipitate are stored in a frozen state, typically at or below -18°C.

Question 4

During a pretransfusion compatibility test, a medical laboratory technician finds that the patient's ABO/Rh type is A positive, and the antibody screen is negative. The crossmatch is performed with an A positive donor unit. The immediate spin crossmatch is incompatible (4+). What is the MOST likely cause of this discrepancy?

Accepted Answer

The patient has an A2 subtype with the presence of anti-A1.

Answer

An A2 individual can produce anti-A1, which would react with A1 cells from the donor unit, causing an incompatibility at immediate spin. The antibody screen is typically performed with O cells, which would not detect anti-A1. An incorrect donor unit label (e.g., group B) would also cause incompatibility, but the A2 with anti-A1 scenario is a classic cause for this specific set of results. An antibody to a low-prevalence antigen is possible but less common, and a cold antibody should have been detected on the screen if the appropriate cells were used.

Question 5

A transfusion reaction workup is initiated on a patient who developed fever, chills, and flank pain 15 minutes into a red blood cell transfusion. The initial laboratory investigation includes a clerical check, a visual check for hemolysis in the post-transfusion specimen, and a Direct Antiglobulin Test (DAT). Which of these findings would most strongly suggest an acute hemolytic transfusion reaction?

Accepted Answer

Pink or red plasma in the centrifuged post-transfusion specimen.

Answer

Pink or red plasma (hemoglobinemia) in a post-transfusion specimen is a key indicator of intravascular hemolysis, which is the hallmark of a severe acute hemolytic transfusion reaction. A clerical error is a common cause but not a direct finding of hemolysis. A DAT can be positive, but the visual presence of free hemoglobin in the plasma is a more immediate and dramatic indicator of red cell destruction in this clinical context. An increase in temperature is a symptom but is also common in febrile, non-hemolytic reactions.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Blood Bank and Transfusion Questions and Answers