Quality Assurance and Quality Control Flashcards
8 cards from real Phlebotomy Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 8 Quality Assurance and Quality Control flashcards as text
A Levey-Jennings chart plots control values over time against which reference points?
Answer: The mean and standard deviations (±1SD, ±2SD, ±3SD) of the control material
Levey-Jennings charts plot consecutive control values against established mean ±1, 2, and 3 standard deviation (SD) lines, allowing visual detection of trends and rule violations.
Westgard's 1₃ₛ rule states that a QC run is rejected when:
Answer: One control value exceeds ±3SD
The 1₃s (one-three-sigma) Westgard rule rejects a run when any single control value exceeds 3 standard deviations from the mean, indicating a probable random error.
A 'shift' in a Levey-Jennings chart is detected when:
Answer: Six or more consecutive control values fall on the same side of the mean
A shift is identified by 6 or more consecutive control values on the same side of the mean (all above or all below), indicating a systematic change in the assay.
What is the purpose of a 'delta check' in laboratory quality assurance?
Answer: To compare a patient's current result with their previous result to detect implausible changes
Delta checks compare a patient's current result to their previous result; implausible differences flag potential sample mislabeling, wrong patient, or hemolysis errors.
Which of the following is a PRE-ANALYTICAL error that can affect laboratory results?
Answer: Hemolyzed specimen due to difficult venipuncture
Pre-analytical errors occur before the specimen reaches the analyzer; hemolysis from difficult venipuncture is a classic pre-analytical error that alters multiple analyte values.
When a laboratory documents QC results, which of the following is the MINIMUM information that must be recorded?
Answer: Date, time, operator ID, lot numbers of controls and reagents, control values, and pass/fail decision
Comprehensive QC documentation is required for regulatory compliance and includes all identifiers (date, time, operator, lot numbers), values, and decision so that patterns can be retrospectively investigated.
The Westgard 10x̄ rule is used to detect which type of QC error?
Answer: Systematic error (bias)
The 10x̄ rule detects systematic bias: when 10 consecutive control values fall on the same side of the mean, it indicates the method has shifted from its calibrated target.
Turnaround time (TAT) monitoring is classified as which type of quality indicator?
Answer: Process quality indicator covering all phases
TAT spans all phases—from order to specimen collection (pre-analytical), analysis (analytical), and result reporting (post-analytical)—making it a comprehensive process quality indicator.