NCCT - National Certified Phlebotomy Technician Specimen Handling and Processing Questions and Answers 1 — Questions and Answers
Question 1: A phlebotomist has collected a blood sample in a serum separator tube (SST). To ensure proper processing, what is the minimum recommended time the tube should be allowed to clot before centrifugation?
- 10 minutes
- 30 minutes (Correct answer)
- 60 minutes
- Immediately after collection
Correct answer: 30 minutes
Serum separator tubes (SSTs) require adequate time for the blood to fully clot before centrifugation. This ensures the formation of a stable fibrin barrier between the serum and the cellular components. According to standard laboratory procedures, the minimum recommended clotting time for an SST is 30 minutes at room temperature.
Question 2: A laboratory requisition specifies that a blood specimen must be protected from light. Which of the following analytes is most likely being tested?
- Glucose
- Sodium
- Bilirubin (Correct answer)
- Complete Blood Count (CBC)
Correct answer: Bilirubin
Bilirubin is a light-sensitive analyte. Exposure to light, especially ultraviolet light, can cause it to break down, leading to falsely low test results. Therefore, specimens for bilirubin testing must be protected from light by using an amber-colored tube or by wrapping the tube in foil.
Question 3: A phlebotomist is preparing several specimens for transport to a reference laboratory. One test requires the plasma to be separated from the cells and frozen. Which of the following is a critical step in this process?
- Centrifuge the tube immediately after collection without waiting for it to clot.
- Freeze the entire whole blood tube before centrifugation.
- Aliquot the plasma into a separate, properly labeled transport tube after centrifugation. (Correct answer)
- Store the separated plasma at room temperature until the courier arrives.
Correct answer: Aliquot the plasma into a separate, properly labeled transport tube after centrifugation.
When a frozen plasma specimen is required, the whole blood tube (e.g., light blue, green, or lavender top) must first be centrifuged to separate the plasma from the red blood cells. After centrifugation, the plasma must be carefully removed (aliquotted) and transferred into a separate, labeled plastic transport tube before being frozen. Freezing the whole blood tube would cause hemolysis and render the specimen unusable.
Question 4: Which of the following is a common reason for a laboratory to reject a blood specimen drawn for a coagulation test, such as a PT or aPTT?
- The light blue top tube is completely filled to the indicated mark.
- The specimen was delivered to the lab within 30 minutes of collection.
- The lavender top tube was drawn before the light blue top tube.
- The light blue top tube is underfilled. (Correct answer)
Correct answer: The light blue top tube is underfilled.
Coagulation tests require a specific blood-to-anticoagulant ratio (9:1). The light blue top tube contains sodium citrate anticoagulant. If the tube is underfilled, the ratio of anticoagulant to blood is too high, which can lead to erroneously prolonged clotting times and inaccurate test results. This is a primary reason for specimen rejection for coagulation studies.
Question 5: During centrifugation of blood specimens, what is the most important principle to follow to ensure the centrifuge operates safely and correctly?
- Always run the centrifuge with the lid open for better ventilation.
- Ensure the centrifuge is perfectly balanced by placing tubes directly opposite each other. (Correct answer)
- Spin tubes for the longest possible time to ensure maximum separation.
- Use the highest speed setting for all types of specimen tubes.
Correct answer: Ensure the centrifuge is perfectly balanced by placing tubes directly opposite each other.
Balancing the centrifuge is critical for safety and proper function. Every tube placed in the rotor must be balanced by another tube of the same type, size, and fill volume placed directly opposite it. An unbalanced centrifuge can vibrate excessively, potentially causing damage to the machine and breakage of specimen tubes.
Question 6: A phlebotomist is sending a refrigerated specimen to a reference lab. According to standard transport guidelines, what is the appropriate temperature range that must be maintained?
- Below 0°C
- 2-8°C (Correct answer)
- 15-25°C
- 37°C
Correct answer: 2-8°C
Refrigerated specimens must be kept within a strict temperature range to maintain analyte stability. The universally accepted range for refrigerated medical specimens during transport and storage is 2-8°C (35.6-46.4°F). Temperatures below this can cause freezing and hemolysis, while higher temperatures can lead to degradation of the sample.
NCCT - National Certified Phlebotomy Technician Specimen Handling and Processing Questions and Answers 1
A phlebotomist has collected a blood sample in a serum separator tube (SST).
To ensure proper processing, what is the minimum recommended time the tube should be allowed to clot before centrifugation?