Retesting before the laboratory phase is complete, invalidating an original result without identifying an assignable cause, and closing the investigation without deciding whether other batches are affected.
The laboratory phase has to finish first
A documented laboratory investigation — reviewing the method, the calculation, the instrument, the standards and the analyst's execution — comes before any retest. Retesting first produces a passing number and no explanation, and the record shows exactly that sequence.
Invalidation requires an assignable cause
"No laboratory error found" is not a basis for invalidating a result. When the laboratory phase is inconclusive, the investigation moves into production and the original result stands until evidence supports otherwise.
Close the loop on scope
- Which other batches used the same standard, column, reagent lot or analyst
- Whether the same method has produced similar results elsewhere
- Whether stability or released product is implicated
- What the effectiveness check will measure, and when
Reviewed by the named consultant. Last updated July 14, 2026. General information only — not regulatory or legal advice for a specific situation.