CMLA Specimen Collection & Handling 3 — Questions and Answers
Question 1: Which of the following best describes the proper technique for mixing an EDTA tube after collection?
- Shake vigorously for 10 seconds
- Invert gently 8–10 times (Correct answer)
- Leave undisturbed for 5 minutes
- Centrifuge immediately without mixing
Correct answer: Invert gently 8–10 times
EDTA tubes should be gently inverted 8–10 times to thoroughly mix the anticoagulant with blood without causing hemolysis.
Question 2: A urine specimen for culture must be collected using which method to avoid contamination?
- First morning void into any clean container
- Midstream clean-catch into a sterile cup (Correct answer)
- Catheter bag drainage after 2 hours
- Random void with no special preparation
Correct answer: Midstream clean-catch into a sterile cup
Midstream clean-catch technique minimizes urethral flora contamination for accurate urine culture results.
Question 3: Which specimen type is collected in a yellow (ACD) tube?
- Serum for chemistry panels
- Whole blood for blood banking and HLA typing (Correct answer)
- Plasma for coagulation studies
- Urine for culture
Correct answer: Whole blood for blood banking and HLA typing
Yellow ACD (acid citrate dextrose) tubes are used for whole blood specimens in blood banking, HLA phenotyping, and paternity testing.
Question 4: A specimen labeled 'STAT' is received in the lab 45 minutes after collection with no temperature notation. What should the laboratory assistant do?
- Process it immediately without question
- Check for visible hemolysis and contact the ordering unit (Correct answer)
- Reject it automatically as out of time
- Re-centrifuge and proceed
Correct answer: Check for visible hemolysis and contact the ordering unit
The assistant should assess the specimen for hemolysis or other integrity issues and contact the ordering unit to clarify handling before processing.
Question 5: What is the minimum volume typically required in a sodium citrate tube to maintain the correct blood-to-anticoagulant ratio?
- At least 50% full
- Exactly 100% full
- At least 90% of the stated tube volume (no more than 10% underfilled) (Correct answer)
- Any amount is acceptable
Correct answer: At least 90% of the stated tube volume (no more than 10% underfilled)
Sodium citrate tubes must be filled to at least 90% of capacity to maintain the 9:1 blood-to-anticoagulant ratio required for valid coagulation testing.
Question 6: Which needle gauge is most commonly used for routine adult venipuncture?
- 18 gauge
- 21–22 gauge (Correct answer)
- 25 gauge
- 27 gauge
Correct answer: 21–22 gauge
21–22 gauge needles are standard for adult venipuncture, balancing flow rate with patient comfort and minimal hemolysis.
Question 7: When collecting a blood specimen from a patient receiving IV fluids, which site is preferred?
- The same arm as the IV, just below the insertion site
- The opposite arm from the IV site (Correct answer)
- The femoral vein regardless of IV location
- Either arm since IV fluids do not affect results
Correct answer: The opposite arm from the IV site
Blood should be drawn from the opposite arm of an IV site to prevent dilution or contamination of the specimen with infused fluids.
CMLA Specimen Collection & Handling 3
Which of the following best describes the proper technique for mixing an EDTA tube after collection?