CMLA Laboratory Equipment Operation & Maintenance 3 — Questions and Answers
Question 1: What does a Levy-Jennings chart primarily monitor in a clinical laboratory?
- Inventory levels of reagents
- Quality control results over time to detect trends and shifts (Correct answer)
- Patient result turnaround times
- Equipment maintenance schedules
Correct answer: Quality control results over time to detect trends and shifts
Levy-Jennings charts plot QC values over time, allowing laboratory staff to detect shifts, trends, and random errors visually.
Question 2: When should a biological safety cabinet (BSC) blower be turned on before beginning work?
- Immediately before placing specimens inside
- At least 5 minutes before use to purge and stabilize airflow (Correct answer)
- Only after specimens are already inside
- At the start of each work week
Correct answer: At least 5 minutes before use to purge and stabilize airflow
Running the BSC blower for at least 5 minutes before use ensures stable, uncontaminated airflow that protects both the worker and specimen.
Question 3: An automated hematology analyzer produces a flagged result for white blood cell count. What is the appropriate next step?
- Report the result as flagged without further action
- Prepare and review a peripheral blood smear for manual differential (Correct answer)
- Repeat the test on a different analyzer without review
- Dilute the sample and re-run
Correct answer: Prepare and review a peripheral blood smear for manual differential
Flagged hematology results require peripheral smear review to confirm or further characterize abnormalities before reporting.
Question 4: Which type of water is recommended for most laboratory reagent preparation?
- Tap water filtered through a coffee filter
- Deionized or distilled Type I or Type II reagent-grade water (Correct answer)
- Bottled drinking water
- Reverse osmosis water from a home unit
Correct answer: Deionized or distilled Type I or Type II reagent-grade water
Reagent-grade (Type I or II) water meets purity standards for conductivity and contaminants necessary for accurate laboratory testing.
Question 5: What action should be taken if a pH meter reads outside the expected range when checked with a standard buffer?
- Adjust the pH of the buffer to match the meter
- Recalibrate the meter using certified buffers at known pH values (Correct answer)
- Replace the meter immediately
- Add distilled water to the electrode well
Correct answer: Recalibrate the meter using certified buffers at known pH values
Recalibration with certified buffers corrects the electrode response curve so subsequent measurements are accurate.
Question 6: Why is it important to use appropriately sized tubes when operating a centrifuge?
- Larger tubes always spin faster
- Mismatched tube sizes can cause imbalance and rotor stress, risking equipment failure (Correct answer)
- Tube size affects only the sample volume collected
- Smaller tubes require longer centrifugation times
Correct answer: Mismatched tube sizes can cause imbalance and rotor stress, risking equipment failure
Tubes must fit the rotor buckets properly to prevent imbalance, vibration, and potential catastrophic rotor failure.
Question 7: Which parameter is most critical to verify before using a new lot of control material on a chemistry analyzer?
- The expiration date printed on the package
- That new lot values fall within acceptable ranges established by parallel testing (Correct answer)
- The color of the control material
- The control manufacturer's name
Correct answer: That new lot values fall within acceptable ranges established by parallel testing
New lot controls must be validated by parallel runs with the current lot to establish mean and acceptable ranges before the old lot expires.
CMLA Laboratory Equipment Operation & Maintenance 3
What does a Levy-Jennings chart primarily monitor in a clinical laboratory?