CLC CLC Specimen Collection, Handling & Pre-Analytical Processes 2 — Questions and Answers
Question 1: A laboratory consultant notices that hemolysis interference is causing falsely elevated potassium results. Which pre-analytical intervention would best reduce this problem?
- Adding a hemolysis index threshold and reporting with a comment
- Training phlebotomists on proper technique and minimizing tourniquet time (Correct answer)
- Switching to plasma specimens only
- Diluting all potassium specimens 1:2 before analysis
Correct answer: Training phlebotomists on proper technique and minimizing tourniquet time
The most effective long-term intervention is training phlebotomists to use proper technique and limit tourniquet time, which directly reduces hemolysis at the source.
Question 2: Which labeling requirement is considered the minimum for patient specimen identification according to laboratory safety and accreditation standards?
- Collector's initials only
- Patient full name and date of birth (or second unique identifier) (Correct answer)
- Physician name and test ordered
- Room number and date of collection
Correct answer: Patient full name and date of birth (or second unique identifier)
At minimum, specimens must be labeled with the patient's full name and a second unique identifier (such as date of birth or medical record number) to prevent misidentification.
Question 3: A 24-hour urine collection for creatinine clearance requires special pre-collection instructions. Which instruction is most critical for accurate results?
- Collect only morning specimens
- Discard the first void, then collect all urine for exactly 24 hours (Correct answer)
- Refrigerate only the last specimen
- Add no preservative to the container
Correct answer: Discard the first void, then collect all urine for exactly 24 hours
The standard 24-hour urine protocol requires discarding the first morning void (to clear residual urine), then collecting all urine for the next 24 hours to ensure a complete timed collection.
Question 4: When collecting a blood culture, which antiseptic preparation sequence follows current best practice to minimize contamination rates?
- 70% isopropyl alcohol scrub only
- Povidone-iodine only, air-dried for 30 seconds
- 70% isopropyl alcohol followed by chlorhexidine gluconate (or povidone-iodine), allowed to dry fully (Correct answer)
- No skin prep needed if gloves are worn
Correct answer: 70% isopropyl alcohol followed by chlorhexidine gluconate (or povidone-iodine), allowed to dry fully
Current best practice for blood culture collection uses 70% isopropyl alcohol followed by chlorhexidine gluconate (or povidone-iodine), allowed to fully dry to minimize skin flora contamination.
Question 5: A laboratory consultant is reviewing cold agglutinin test pre-analytical requirements. What is the critical handling step for this specimen?
- Refrigerate immediately after collection
- Keep the specimen at 37°C from collection through serum separation (Correct answer)
- Freeze immediately in dry ice
- Centrifuge within 5 minutes of collection at high speed
Correct answer: Keep the specimen at 37°C from collection through serum separation
Cold agglutinin specimens must be kept warm (37°C) from collection through serum separation because cooling causes antibody binding to RBCs, making them undetectable.
Question 6: Which pre-analytical variable most commonly causes a falsely decreased glucose result when specimens are not processed promptly?
- Lipemia in the specimen
- Glycolysis by RBCs and WBCs consuming glucose over time (Correct answer)
- Elevated bilirubin interfering with photometric assay
- Incorrect tube additive
Correct answer: Glycolysis by RBCs and WBCs consuming glucose over time
Cellular metabolism (glycolysis) continues in unprocessed whole blood, consuming glucose at a rate of approximately 5–7% per hour at room temperature, causing falsely low glucose results.
CLC CLC Specimen Collection, Handling & Pre-Analytical Processes 2
A laboratory consultant notices that hemolysis interference is causing falsely elevated potassium results.
Which pre-analytical intervention would best reduce this problem?