Comparing SOP versions for change control

Updated 30 September 2026

When an SOP, test method, protocol or specification is revised, reviewers need to confirm two things: that every intended change is there, and that nothing else changed. A side-by-side read is slow and easy to get wrong. A structured comparison makes the review faster and gives you something to keep with the change record.

What to compare

• The current effective version against the proposed revision. Not the previous draft, and not a copy with tracked changes still in it.
• Final text only. If either file still has tracked changes or comments, resolve them first, or at least note that the comparison treats them as accepted.

Where important changes hide

• Tables: acceptance criteria, limits, system suitability requirements and sampling plans. A limit changing from 2.0 to 1.8 is one cell.
• Numbers inside sentences: times, temperatures, volumes, counts ("inject five times" becoming "six times").
• Moved steps: a step moved before or after another can change the process even though no words changed.
• Formatting that carries meaning: a word made bold, like must, or a sentence moved into a warning box.
• Headers and footers: version numbers, effective dates and document IDs.
• References: removed or updated pharmacopoeia and guideline references.

A simple review checklist

1. Compare the effective version with the revision.
2. Go through the change list and match each change to the change request or rationale.
3. Flag any change that isn't explained. Those are the ones that need a question.
4. Check the header and footer changes match the new version number and dates.
5. Save the comparison report with the change record, so the review can be traced to the exact files.

Keeping a record

A comparison report is most useful when it identifies exactly which files were compared. RevisionProof's report lists every change with its location and section, and includes a SHA-256 hash of each file, so anyone can confirm later that the report belongs to those exact versions.

RevisionProof is a review aid, not a validated computerised system. If you use it as part of a GMP process, assess it under your own computerised system procedures, and keep a person responsible for the review decision.

Why privacy matters here

SOPs and specifications are usually confidential, and many companies don't allow them to be uploaded to online tools. RevisionProof compares files inside your browser and is blocked from sending data, so it can be used without the document leaving your computer.