Certified Phlebotomy Technician Phlebotomy Fundamentals Questions and Answers — Questions and Answers
Question 1: A phlebotomist is performing a capillary puncture on a healthy adult's finger to collect specimens for a blood smear, a CBC, and a serum chemistry test. What is the correct order for collecting these specimens?
- Serum tube, EDTA tube, blood smear
- Blood smear, EDTA tube, serum tube (Correct answer)
- EDTA tube, serum tube, blood smear
- Blood smear, serum tube, EDTA tube
Correct answer: Blood smear, EDTA tube, serum tube
For capillary collections, the order of draw is different from venipuncture to minimize the effects of clotting. Blood smears are made first from the fresh drop of blood. Next, EDTA tubes (for CBC) are collected to prevent platelet clumping. Lastly, serum tubes are collected, as they are intended to clot.
Question 2: During a venipuncture, the phlebotomist notices a hematoma forming at the site. Which of the following is the most appropriate immediate action?
- Complete the draw as quickly as possible.
- Adjust the needle's depth to see if blood flow improves.
- Release the tourniquet, withdraw the needle, and apply firm pressure. (Correct answer)
- Ask the patient to apply pressure while the phlebotomist gathers more supplies.
Correct answer: Release the tourniquet, withdraw the needle, and apply firm pressure.
If a hematoma begins to form, it indicates that blood is leaking into the tissue surrounding the vein. The correct procedure is to immediately stop the blood draw by releasing the tourniquet, removing the needle, and applying firm, direct pressure to the site to minimize the size of the hematoma and prevent further injury.
Question 3: A gray-topped tube is selected for blood collection. What is the primary function of the sodium fluoride additive in this tube?
- To enhance the clotting process.
- To bind with calcium and prevent coagulation.
- To preserve glucose in the sample. (Correct answer)
- To separate serum from the cells.
Correct answer: To preserve glucose in the sample.
Gray-topped tubes contain sodium fluoride, which is an antiglycolytic agent that inhibits the breakdown of glucose (glycolysis) within the blood sample. They also contain potassium oxalate, an anticoagulant. This combination ensures an accurate glucose measurement, especially if testing is delayed.
Question 4: A patient experiences a sharp, radiating pain down their arm as the needle is inserted. This is a potential sign of:
- A collapsing vein.
- An arterial puncture.
- Nerve contact. (Correct answer)
- Hemoconcentration.
Correct answer: Nerve contact.
A sharp, electric, or radiating pain is a classic sign that the needle has come into contact with a nerve. If this occurs, the phlebotomist should immediately withdraw the needle and terminate the venipuncture to prevent potential nerve damage.
Question 5: When processing a blood sample in a serum separator tube (SST), which step is critical for proper specimen quality?
- Centrifuging the tube immediately after collection.
- Allowing the tube to clot fully before centrifugation. (Correct answer)
- Inverting the tube vigorously 15-20 times.
- Placing the tube on ice as soon as it is filled.
Correct answer: Allowing the tube to clot fully before centrifugation.
For a serum separator tube (SST), the blood must be allowed to clot completely before being placed in a centrifuge. This usually takes about 30 minutes at room temperature. Centrifuging too early can result in a fibrin-rich serum or incomplete separation, compromising the specimen's integrity.
Question 6: Which of the following situations would require a phlebotomist to draw a 'discard' tube before collecting a specimen for a coagulation test in a light blue top tube?
- When it is the first tube drawn using a standard evacuated tube system.
- When collecting from a patient with a high hematocrit.
- When using a winged infusion set (butterfly needle). (Correct answer)
- When the patient has been fasting for more than 12 hours.
Correct answer: When using a winged infusion set (butterfly needle).
When using a winged infusion set, the air in the tubing will displace blood, leading to an underfilled tube. For coagulation tests (light blue top), the 9:1 blood-to-anticoagulant ratio is critical. Drawing a discard tube first purges the air from the tubing, ensuring the light blue top tube fills to the correct volume.
