PCT Phlebotomy 4 — Questions and Answers
Question 1: A PCT is about to collect blood from a patient in isolation for MRSA. Which PPE must be donned BEFORE entering the room?
- Gloves only
- Gloves and mask
- Gown and gloves at minimum, per contact precautions (Correct answer)
- N95 respirator, gown, and gloves
Correct answer: Gown and gloves at minimum, per contact precautions
MRSA requires contact precautions, which mandate gown and gloves before entering; N95 is reserved for airborne precautions.
Question 2: Which specimen must be transported on ice to the laboratory?
- Serum separator tube for chemistry panel
- Lavender top for CBC
- Arterial blood gas (ABG) syringe (Correct answer)
- Light blue top for PT
Correct answer: Arterial blood gas (ABG) syringe
ABG specimens must be chilled on ice to stop continued cellular metabolism that would alter pH, pO2, and pCO2 values.
Question 3: A lavender-top tube is underfilled to only half capacity. Which test will be MOST affected?
- Glucose
- CBC and differential (Correct answer)
- Lipid panel
- Liver function tests
Correct answer: CBC and differential
The EDTA-to-blood ratio is critical for CBC; excess anticoagulant shrinks red cells (echinocytosis) and skews MCV and hematocrit.
Question 4: When using a butterfly needle for venipuncture, a discard tube should be drawn FIRST when collecting:
- A green-top heparin tube
- A gold SST tube
- A light blue sodium citrate tube (Correct answer)
- A lavender EDTA tube
Correct answer: A light blue sodium citrate tube
The dead space in the butterfly tubing contains air that would underfill the citrate tube and alter the 9:1 blood-to-citrate ratio, so a discard tube is drawn first.
Question 5: Prolonged tourniquet application (>1 minute) can cause:
- Hemodilution
- Hemoconcentration (Correct answer)
- Decreased potassium levels
- Improved vein visibility without side effects
Correct answer: Hemoconcentration
Extended tourniquet use causes fluid to shift out of vessels into tissues, concentrating large molecules and cells in the remaining blood.
Question 6: Which of the following best describes the practice of 'vein palpation'?
- Using a blood pressure cuff to locate veins
- Using the index finger to feel for the vein's bounce and direction before needling (Correct answer)
- Applying heat to increase vein size
- Tapping the site vigorously to cause vasodilation
Correct answer: Using the index finger to feel for the vein's bounce and direction before needling
Palpation with the index finger identifies vein depth, direction, and resilience (bounce), which guides successful needle placement.
Question 7: The gray-top tube contains fluoride and oxalate primarily to:
- Prevent hemolysis
- Preserve glucose by inhibiting glycolysis (Correct answer)
- Chelate calcium for coagulation testing
- Maintain red cell morphology
Correct answer: Preserve glucose by inhibiting glycolysis
Sodium fluoride inhibits the glycolytic enzymes that would otherwise cause red cells to consume glucose, keeping glucose levels stable for hours.
PCT Phlebotomy 4
A PCT is about to collect blood from a patient in isolation for MRSA.
Which PPE must be donned BEFORE entering the room?