CLT Equipment Operation & Maintenance 3 — Questions and Answers
Question 1: An autoclave used for sterilization of laboratory materials fails its biological indicator (Geobacillus stearothermophilus spore strip) test. What is the correct response?
- Re-run the load once more and check the chemical indicator instead
- Remove the autoclave from service, notify supervisor, and investigate the failure (Correct answer)
- Increase the sterilization time by 5 minutes and retest
- Accept the load if the chemical indicator strip showed a color change
Correct answer: Remove the autoclave from service, notify supervisor, and investigate the failure
A failed biological indicator means sterilization was not achieved; the autoclave must be taken out of service and the failure investigated before further use.
Question 2: When calibrating a laboratory balance, certified calibration weights must be:
- Handled with bare hands for best grip
- Handled with forceps or gloves to prevent oils from altering their mass (Correct answer)
- Stored in a humid environment to prevent static charge
- Verified only by the manufacturer every 5 years
Correct answer: Handled with forceps or gloves to prevent oils from altering their mass
Skin oils and moisture from bare hands can alter the mass of precision calibration weights, so forceps or clean gloves must always be used when handling them.
Question 3: A co-oximeter in the blood gas laboratory requires a reference solution check. The purpose of this check is to:
- Verify the wavelength accuracy for multi-wavelength hemoglobin measurements (Correct answer)
- Confirm adequate sample volume before analysis
- Test the electrode membrane integrity
- Measure the barometric pressure compensation
Correct answer: Verify the wavelength accuracy for multi-wavelength hemoglobin measurements
Co-oximeters use multiple wavelengths to distinguish oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and methemoglobin; reference solution checks verify wavelength calibration.
Question 4: Which action is required when a refrigerator used to store reagents reads 10°C on the temperature log, exceeding the 2–8°C required range?
- Adjust the thermostat and continue using reagents stored inside
- Quarantine all temperature-sensitive reagents, document, and notify the supervisor (Correct answer)
- Move reagents to a -20°C freezer temporarily
- Record the excursion and continue normal operations if below 15°C
Correct answer: Quarantine all temperature-sensitive reagents, document, and notify the supervisor
Reagents stored outside their required temperature range may be compromised; they must be quarantined and the excursion documented and reported per laboratory policy.
Question 5: What does a Levy-Jennings chart primarily display?
- Patient results plotted against reference intervals over time
- Control values plotted sequentially to visualize trends and shifts (Correct answer)
- Reagent lot-to-lot comparison data
- Calibration curve linearity data
Correct answer: Control values plotted sequentially to visualize trends and shifts
A Levy-Jennings chart plots sequential control values against time, with ±1, ±2, and ±3 SD lines, allowing visualization of trends, shifts, and random error.
Question 6: The carryover rate of an automated analyzer is best assessed by:
- Running the same sample 20 times and calculating the CV
- Analyzing a high-concentration sample followed immediately by a low-concentration sample (Correct answer)
- Comparing duplicate patient results over one week
- Checking the sample probe for visible contamination
Correct answer: Analyzing a high-concentration sample followed immediately by a low-concentration sample
Carryover is measured by running a very high-concentration sample followed by a low-concentration sample and calculating the amount of high-level material contaminating the low-level result.
Question 7: When a flow cytometer laser alignment is compromised, which control parameter is MOST directly affected?
- Side scatter coefficient of variation (CV) for beads (Correct answer)
- Fluorescence compensation matrix
- Detector voltage settings
- Sample injection pressure
Correct answer: Side scatter coefficient of variation (CV) for beads
Laser alignment directly affects light scatter uniformity; a misaligned laser produces high CVs on calibration bead side scatter measurements, indicating poor alignment.
CLT Equipment Operation & Maintenance 3
An autoclave used for sterilization of laboratory materials fails its biological indicator (Geobacillus stearothermophilus spore strip) test.
What is the correct response?