Certified Phlebotomy Technician Exam Specimen Handling and Processing 3 — Questions and Answers
Question 1: A specimen for ammonia testing must be:
- Kept at 37°C and processed within 4 hours
- Placed on ice immediately and tested within 15–30 minutes (Correct answer)
- Stored at room temperature for up to 2 hours
- Refrigerated for 24 hours before testing
Correct answer: Placed on ice immediately and tested within 15–30 minutes
Ammonia specimens must be placed on ice immediately after collection and processed within 15–30 minutes because red blood cells continue to produce ammonia at room temperature.
Question 2: What is the primary reason for avoiding vigorous shaking of blood collection tubes?
- It activates coagulation factors
- It causes hemolysis by rupturing red blood cells (Correct answer)
- It deactivates tube additives
- It increases glycolysis
Correct answer: It causes hemolysis by rupturing red blood cells
Vigorous shaking causes mechanical hemolysis by rupturing red blood cells, releasing intracellular contents that interfere with test results.
Question 3: Which specimen type is required for a prothrombin time (PT) test?
- Serum in a red-top tube
- Whole blood in an EDTA tube
- Plasma in a sodium citrate tube (Correct answer)
- Urine in a sterile cup
Correct answer: Plasma in a sodium citrate tube
PT testing requires plasma anticoagulated with sodium citrate (light blue-top tube) because sodium citrate chelates calcium to preserve coagulation factors.
Question 4: When aliquoting a specimen, which technique prevents cross-contamination between aliquots?
- Using the same pipette for all aliquots
- Changing pipette tips between each aliquot transfer (Correct answer)
- Mixing all aliquots together before distribution
- Storing all aliquots in the same tube
Correct answer: Changing pipette tips between each aliquot transfer
Changing pipette tips between each transfer prevents carryover and cross-contamination of specimens destined for different tests.
Question 5: A specimen for lactic acid testing should be transported:
- At room temperature in a red-top tube
- On ice in a gray-top or lithium heparin tube (Correct answer)
- Frozen immediately after collection
- In a light-protected amber bag
Correct answer: On ice in a gray-top or lithium heparin tube
Lactic acid specimens must be placed on ice immediately and processed quickly because glycolysis by red blood cells will falsely elevate lactate levels.
Question 6: What does the term 'hemolysis' refer to in the context of specimen quality?
- Clotting of the specimen
- Rupture of red blood cells releasing hemoglobin into plasma/serum (Correct answer)
- Bacterial contamination of the specimen
- Separation of serum from plasma
Correct answer: Rupture of red blood cells releasing hemoglobin into plasma/serum
Hemolysis refers to the rupture of red blood cells, releasing hemoglobin and intracellular contents (potassium, LDH, AST) that interfere with many laboratory tests.
Question 7: For a 24-hour urine collection, what instruction must the patient follow at the start of the collection period?
- Collect the first morning void and include it
- Discard the first morning void, then collect all subsequent urine (Correct answer)
- Begin collection at noon regardless of voiding schedule
- Collect only nighttime urine samples
Correct answer: Discard the first morning void, then collect all subsequent urine
The patient discards the first morning void to establish a clean start time, then collects all urine for the next 24 hours including the final void.
Certified Phlebotomy Technician Exam Specimen Handling and Processing 3
A specimen for ammonia testing must be: