ASPT Specimen Handling and Processing 4 — Questions and Answers
Question 1: When processing a specimen for plasma, what step differentiates it from serum preparation?
- Plasma requires a clot activator tube
- Plasma can be centrifuged immediately without waiting for clot formation (Correct answer)
- Plasma must be refrigerated before centrifugation
- Plasma requires twice the centrifugation time
Correct answer: Plasma can be centrifuged immediately without waiting for clot formation
Plasma is obtained from anticoagulated blood that can be centrifuged immediately, whereas serum requires a 30-minute clotting period before centrifugation.
Question 2: Which of the following is a pre-analytical error that can affect specimen quality?
- Incorrect reagent preparation in the lab
- Instrument calibration error
- Prolonged tourniquet application during collection (Correct answer)
- Analyzer software malfunction
Correct answer: Prolonged tourniquet application during collection
Prolonged tourniquet application (>1 minute) causes hemoconcentration and hemolysis, which are pre-analytical errors that occur before specimen analysis.
Question 3: What type of specimen is required for a prothrombin time (PT) test?
- Serum from a red top tube
- Whole blood from an EDTA tube
- Plasma from a sodium citrate tube (Correct answer)
- Plasma from a heparin tube
Correct answer: Plasma from a sodium citrate tube
PT/INR testing requires plasma anticoagulated with sodium citrate (light blue top) because citrate preserves clotting factors needed for coagulation testing.
Question 4: A specimen arrives at the lab with visible lipemia. Which test result is most likely to be affected?
- Complete blood count (CBC)
- Potassium
- Triglycerides (Correct answer)
- Prothrombin time (PT)
Correct answer: Triglycerides
Lipemia indicates elevated triglycerides in the blood, which is directly reflected in triglyceride test results and can interfere with other optical-based assays.
Question 5: What is the recommended angle for inserting the needle during venipuncture to minimize patient discomfort?
- 5–10 degrees
- 15–30 degrees (Correct answer)
- 45–60 degrees
- 70–90 degrees
Correct answer: 15–30 degrees
A 15–30 degree angle is recommended for venipuncture as it allows proper needle entry into the vein while minimizing tissue trauma.
Question 6: Which specimen type is required for erythrocyte sedimentation rate (ESR) testing?
- Serum
- Heparinized plasma
- EDTA whole blood (Correct answer)
- Sodium citrate plasma
Correct answer: EDTA whole blood
ESR testing requires EDTA whole blood because the test measures how fast red blood cells settle, requiring intact cells in an anticoagulated state.
Question 7: What action should be taken if a blood culture bottle shows a positive flag before expected?
- Discard the bottle as likely contaminated
- Re-incubate for the full time period
- Notify the lab immediately for Gram stain and subculture (Correct answer)
- Add more blood to the culture bottle
Correct answer: Notify the lab immediately for Gram stain and subculture
A positive blood culture flag indicates bacterial growth and requires immediate Gram staining and subculturing to identify the organism for urgent patient treatment.
ASPT Specimen Handling and Processing 4
When processing a specimen for plasma, what step differentiates it from serum preparation?