Medical Laboratory TechnicianĀ Exam Medical Laboratory Technician Laboratory Operations and QC Questions and Answers 2 ā Questions and Answers
Question 1: A laboratory receives a proficiency testing sample that yields results outside the acceptable range. What is the appropriate first step?
- Report the result and continue testing patient samples
- Investigate the cause of the discrepancy before resuming patient testing (Correct answer)
- Discard the proficiency sample and request a new one
- Adjust the instrument calibration to match the expected value
Correct answer: Investigate the cause of the discrepancy before resuming patient testing
When proficiency testing results fall outside acceptable ranges, the laboratory must investigate the root cause before continuing patient testing to ensure accurate results.
Question 2: Which document defines the step-by-step procedure for performing a specific laboratory test?
- Quality manual
- Standard operating procedure (Correct answer)
- Organizational chart
- Safety data sheet
Correct answer: Standard operating procedure
A standard operating procedure (SOP) provides detailed, step-by-step instructions for performing a specific laboratory test consistently.
Question 3: What is the primary purpose of running a blank sample during analytical testing?
- To calibrate the instrument for the next patient sample
- To verify the reagent lot number is correct
- To detect contamination or background interference (Correct answer)
- To satisfy proficiency testing requirements
Correct answer: To detect contamination or background interference
A blank sample contains no analyte and is used to detect contamination or background signal that could interfere with accurate patient results.
Question 4: In a Westgard multirule QC system, a 2-2s violation occurs when which of the following is observed?
- One control exceeds 2 standard deviations from the mean
- Two consecutive controls exceed 2 standard deviations on the same side of the mean (Correct answer)
- Two consecutive controls exceed 2 standard deviations on opposite sides of the mean
- The range between two controls exceeds 4 standard deviations
Correct answer: Two consecutive controls exceed 2 standard deviations on the same side of the mean
A 2-2s violation is triggered when two consecutive control results both exceed 2 standard deviations from the mean on the same side, indicating systematic error.
Question 5: Which type of error is best detected by analyzing a trend of control values that progressively shift in one direction over several days?
- Random error
- Systematic error (Correct answer)
- Pre-analytical error
- Clerical error
Correct answer: Systematic error
A progressive shift in control values over time indicates systematic error, often caused by reagent deterioration or calibration drift.
Question 6: What is the minimum frequency for verifying the temperature of a laboratory refrigerator used to store reagents, according to standard laboratory practice?
- Weekly
- Monthly
- Daily (Correct answer)
- Only when an out-of-range QC result occurs
Correct answer: Daily
Laboratory refrigerators storing reagents and specimens must have their temperatures checked and recorded daily to ensure proper storage conditions.
Medical Laboratory TechnicianĀ Exam Medical Laboratory Technician Laboratory Operations and QC Questions and Answers 2
A laboratory receives a proficiency testing sample that yields results outside the acceptable range.
What is the appropriate first step?