Certified Phlebotomy Technician Exam Specimen Handling and Processing 5 — Questions and Answers
Question 1: Which of the following is a common cause of pre-analytical error in specimen handling?
- Incorrect reagent calibration in the analyzer
- Specimen collected from an IV line above an infusion site (Correct answer)
- Analyzer malfunction during measurement
- Laboratory technician misreading a result
Correct answer: Specimen collected from an IV line above an infusion site
Collecting blood from a site proximal to an IV infusion dilutes or contaminates the specimen with IV fluid, a classic pre-analytical error that invalidates results.
Question 2: What is the maximum storage time for most whole blood specimens collected in EDTA at 2–8°C before CBCs become unreliable?
- 1 hour
- 24 hours (Correct answer)
- 72 hours
- 1 week
Correct answer: 24 hours
Most CBC parameters remain stable in EDTA at refrigerated temperatures for up to 24 hours, after which platelet swelling and morphology changes compromise results.
Question 3: A serum separator tube (SST) must be inverted how many times after collection?
- 0 times — do not mix
- 3–4 times
- 5 times (Correct answer)
- 10 times
Correct answer: 5 times
SST tubes should be gently inverted 5 times to activate the clot activator coating while avoiding hemolysis from over-mixing.
Question 4: Which test requires a fasting specimen for accurate results?
- Complete blood count (CBC)
- Fasting lipid panel (Correct answer)
- Blood culture
- Urinalysis
Correct answer: Fasting lipid panel
A fasting lipid panel requires the patient to fast for 9–12 hours before collection because dietary fat raises triglycerides and affects calculated LDL values.
Question 5: What is the purpose of the gel separator in SST and PST tubes?
- To anticoagulate the specimen
- To form a physical barrier between cells and serum/plasma after centrifugation (Correct answer)
- To lyse red blood cells for plasma testing
- To neutralize tube additives
Correct answer: To form a physical barrier between cells and serum/plasma after centrifugation
The thixotropic gel in separator tubes migrates during centrifugation to form a stable physical barrier between the cellular layer and the serum or plasma layer.
Question 6: A specimen labeled 'STAT' should be processed within what timeframe from receipt in the laboratory?
- Within 5 minutes
- Within 30–60 minutes (Correct answer)
- Within 2 hours
- Within 4 hours
Correct answer: Within 30–60 minutes
STAT specimens require processing and result reporting within 30–60 minutes of receipt to meet clinical urgency standards and patient care needs.
Question 7: Which action should be taken if a specimen arrives in the lab with visible clots in a tube that requires whole blood (e.g., EDTA)?
- Centrifuge and use the plasma
- Process normally since clots are common
- Reject the specimen and request a recollection (Correct answer)
- Warm the specimen to dissolve the clot
Correct answer: Reject the specimen and request a recollection
A clotted EDTA specimen must be rejected because clot formation means the anticoagulant failed to work, and results (especially CBC and coagulation-related tests) will be inaccurate.
Certified Phlebotomy Technician Exam Specimen Handling and Processing 5
Which of the following is a common cause of pre-analytical error in specimen handling?