Troubleshooting, Error Investigation, and Corrective Action
Core concepts
Troubleshooting begins with classifying the error as pre-analytical, analytical, or post-analytical. Candidates should understand root cause analysis, the 5 Whys, fishbone diagrams, and corrective and preventive action (CAPA). Know the difference between correction (fixing the immediate problem) and corrective action (preventing recurrence).
Investigation approach
Verify specimen integrity and identity first, then check reagents, calibration, controls, and instrument status. Review trends rather than isolated events. Document findings and verify effectiveness of the corrective action.
Traps in questions
- Jumping to instrument failure before ruling out specimen problems.
- Confusing correction with corrective action.
- Closing a CAPA without verifying effectiveness.
- Ignoring near-misses as non-events.
Worked rule of thumb
When a single result is aberrant, first repeat the test and verify specimen identity. If the result is confirmed and controls are in range, investigate the specimen and pre-analytical variables. If controls are out, stop and investigate the analytical system before reporting.
Study guidance
Practice structuring an investigation from symptom to root cause to corrective action to effectiveness check.