An out-of-specification (OOS) result must be investigated before anything is retested or released. The phased approach described in the US FDA guidance on investigating OOS results — a laboratory investigation first, then a full-scale investigation if no laboratory error is confirmed — is now the common expectation in the US, EU, UK and India.
What the template covers
- Identification — test, specification limit, result, analyst and instrument.
- Phase I laboratory checklist — method, calculations, instrument, standards, sample preparation, training and raw-data review.
- A hypothesis and retest plan approved by QA before any testing.
- Phase II full-scale investigation — manufacturing review, root cause and impact on other batches.
- Batch disposition, CAPA reference and approvals.
Tips
- Never discard solutions or raw data until the investigation is closed.
- Define the number of retests in your SOP — not after the first one fails.
- An averaged passing result never hides an individual failing one.