Brief · Use case · Quality
Batch Failure Diagnosis.
LiveDiagnosisFind out why a quality attribute keeps failing across batches, the likely cause and the tests that would confirm or refute it.
Batch Failure Diagnosis is a ready-made use case for Quality. It ships under the Diagnosis template.
For quality leaders with repeated out-of-specification results. You get what the batch records show and what has not changed, material, process, method and site explanations weighed against the evidence, the likely cause with a confidence level and what to rule out. Claims are cited or marked as gaps.
Add it to your library to reuse from New → From template. Edit the saved copy in your library on the service form.
The decision
Why has one product had repeated out-of-specification results on a single quality attribute across recent batches at a contract manufacturing site: raw material variability, equipment or process drift, analytical method error, or a change at the site?
The explanations weighed
The diagnosis restates the failures in measurable terms first: which attribute, how many batches, by how much, and since when. It then tests each explanation against the batch records.
| Explanation | What it would look like | What would confirm or refute it |
|---|---|---|
| Raw material variability | A material attribute varies enough between lots to move the result. | Confirmed by results that track material lot. Refuted if failures occur across lots. |
| Equipment or process drift | The process or equipment has moved away from its validated state.2 | Confirmed by process data that trends with the failures. Refuted if the data are stable. |
| Analytical method error | The test, not the product, is wrong. FDA’s guidance on out-of-specification results describes how a laboratory investigates a result before it is accepted or rejected.1 | Confirmed by a laboratory error found in the investigation or by retest results that differ. Refuted if retests agree. |
| A change at the site | Something changed at the site: people, equipment, supplier or procedure. | Confirmed by a dated change that precedes the first failure. Refuted if no change precedes it. |
What the diagnosis does
The investigation order matters. FDA’s guidance on out-of-specification results sets out how a laboratory investigation precedes a conclusion about the batch. The diagnosis follows that order, so an analytical error is excluded or found before a manufacturing cause is assigned.1
Risk, with its subjectivity named. ICH Q9(R1), which reached its final step in January 2023, revised the quality risk management guideline to address subjectivity, noting that it cannot be eliminated but can be controlled, for example by addressing bias and by designing risk scoring scales with care. The diagnosis states how its judgments were made.2
What has not changed. A cause is plausible only if it changed. The diagnosis lists what did not change at the site, in the process and in the method over the period, so those explanations can be set aside.
How it could be wrong. The likely cause rests on an assumption, such as that batch records are complete. The diagnosis names it and the observation that would break it.
Recommended length
Comprehensive
The question asks you to weigh at least three explanations. The matrix that does that, and the Pareto view of where the effect sits, are in the Comprehensive length. Standard names a cause without the side-by-side.
You can pick another length on the form. The other two stay available.
Assumptions the diagnosis checks
The diagnosis states the assumptions its likely cause rests on and sets what would break each one. Examples for this problem:
- The batch records and the laboratory records are complete and legible.
- The specification and the method are the same across the batches compared.
- Material lot information is traceable to each batch.
Standards, guidance and sources
Quality guidance
The decision practice behind the memo itself is on the template page.
What gets flagged
Any laboratory investigation that was not completed, any change at the site that is not dated, and any explanation the batch records cannot separate.
What arrives
- The problem as stated
- What is actually happening
- Competing explanations
- The likely cause
- What would confirm it
- Where the effect concentrates
- What to rule out
What it will not do
It does not decide what to do about the cause. A Decision Memo takes the diagnosis as its starting point.
It is not a regulatory investigation or a batch disposition decision, and it does not replace the company’s quality system.
It does not prove the cause. It names the most likely cause, says how sure it is, and says what would show it to be wrong.
It does not assign blame. It looks for contributing causes in the system, in the way a blameless postmortem does.
It does not act. Deciding what to do about the cause is a different question; a Decision Memo is the template for it.
References
- [1] U.S. Food and Drug Administration. Investigating Out-of-Specification (OOS) Test Results for Pharmaceutical Production. Guidance for industry. October 2006. Found by search. A later FDA document may exist at fda.gov/media/158416; check the current version.
- [2] International Council for Harmonisation. ICH Q9(R1): Quality Risk Management. Adopted at Step 4 on 18 January 2023 (EMA/CHMP/ICH/24235/2006). Step 4 date and the subjectivity revision as given in the ICH and EMA listings and search excerpts; the guideline was not read in full.
Links checked 9 October 2026
These are the sources the template drew on. None of their authors or issuers has reviewed it.
About the Brief service
A Brief is a written answer from one specialist, at the depth you asked for. It arrives with its sources, and it closes by saying plainly what would change the conclusion. Nothing is hidden behind a summary, and anything the expert could not source is marked as a gap rather than filled in.
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