Quality Control and Laboratory Management
Quality control and laboratory management tests whether you can prove a result is trustworthy and run a laboratory safely. Expect internal quality control, external quality assessment, Westgard rules, documentation, biosafety and audit.
Core rules
- Accuracy is closeness to the true value; precision is closeness of repeated results. Bias is systematic error; imprecision is random error.
- Plot daily controls on a Levey–Jennings chart. Warning rule 1-2s; rejection rules include 1-3s, 2-2s, R-4s, 4-1s and 10x.
- Calibration establishes the relationship between signal and concentration; quality control verifies it daily. Never adjust a control range to fit a failing run.
- External quality assessment or proficiency testing compares your results with peer laboratories and is not the same as internal quality control.
- Documentation: standard operating procedures, records of maintenance, corrective action and staff competency.
- Biosafety: standard precautions, hand hygiene, PPE, safe sharps disposal, spill kits and correct waste segregation.
Worked example
A chemistry control gives 1-3s on the morning run. The rule is violated because one point lies beyond three standard deviations. Stop reporting patient results, repeat the control with a fresh aliquot, and check reagents and calibration. If the repeat is in control, the first value was probably random error; if not, recalibrate and re-run the patient samples from that period. Document the investigation and the corrective action.
Traps
Releasing results during a rejected QC run; accepting external quality assessment results without investigating an unsatisfactory score; and signing off competency for staff who have never been directly observed.