STP Quality Management 4 — Questions and Answers
Question 1: A laboratory notices that IQC results for a glucose assay have gradually shifted upward over 10 days without breaching ±2SD limits. Which Westgard rule flags this trend?
- 1₂s warning rule
- 10x rule (Correct answer)
- R₄s rule
- 2₂s rule
Correct answer: 10x rule
The 10x (10 consecutive) rule flags when ten successive control results fall on the same side of the mean, indicating a systematic shift or trend.
Question 2: What does 'measurement uncertainty' represent in a laboratory result?
- The probability that the analyzer will fail during a run
- A quantitative estimate of the doubt associated with a measurement result (Correct answer)
- The range of values that are clinically acceptable
- The difference between two consecutive patient results
Correct answer: A quantitative estimate of the doubt associated with a measurement result
Measurement uncertainty is a parameter characterizing the dispersion of values that could reasonably be attributed to the measurand, reflecting doubt about the result.
Question 3: Which document type in a quality management system describes WHAT to do and WHY, rather than HOW to do it step by step?
- Standard Operating Procedure (SOP)
- Work Instruction
- Policy (Correct answer)
- Audit checklist
Correct answer: Policy
A policy states high-level intentions and direction (what and why), while SOPs and work instructions describe the detailed steps (how).
Question 4: In laboratory accreditation, what is an 'audit finding' classified as a 'major non-conformance'?
- A paperwork error with no effect on patient safety
- A systemic failure likely to affect the validity of results or patient safety (Correct answer)
- A suggestion for improving efficiency
- A deviation noted during an internal audit only
Correct answer: A systemic failure likely to affect the validity of results or patient safety
A major non-conformance indicates a systemic breakdown or significant failure that directly threatens the reliability of results or patient/staff safety.
Question 5: A laboratory's turnaround time (TAT) for STAT troponin results has increased. Which quality tool would BEST help map the workflow to identify bottlenecks?
- Pareto chart
- Process flow diagram (value stream map) (Correct answer)
- Scatter plot
- Run chart of troponin values
Correct answer: Process flow diagram (value stream map)
A process flow diagram or value stream map visually represents each step in the workflow, making it easy to identify delays, redundancies, and bottlenecks.
Question 6: What is the purpose of a 'blank' in analytical chemistry quality control?
- To calibrate the instrument to the highest expected concentration
- To assess background signal and ensure no contamination contributes to results (Correct answer)
- To verify the linearity of the assay
- To confirm that the reagent lot has not expired
Correct answer: To assess background signal and ensure no contamination contributes to results
A blank (containing no analyte) measures background absorbance or signal, confirming that reagents and matrix do not contribute false positive readings.
Question 7: Under ISO 15189, which of the following is a requirement for the post-examination phase?
- Ensuring samples are collected in the correct order of draw
- Systematic review of results before authorization and release (Correct answer)
- Verifying patient identification at time of collection
- Documenting reagent lot numbers before each analytical run
Correct answer: Systematic review of results before authorization and release
ISO 15189 requires that results be reviewed for plausibility and clinical consistency before authorization, forming part of the post-examination phase.
STP Quality Management 4
A laboratory notices that IQC results for a glucose assay have gradually shifted upward over 10 days without breaching ±2SD limits.
Which Westgard rule flags this trend?