A protocol deviation is any change, divergence, or departure from the study design or procedures defined in the clinical investigation plan that does not have prior IRB/EC approval. Deviations range from minor issues, such as a visit slightly outside its window, to major ones that affect subject safety or data integrity, such as enrolling an ineligible patient. ISO 14155 requires them to be documented, assessed and reported, and recurring deviations should drive corrective action. Under 21 CFR 812.150, deviations to protect a subject in an emergency must be reported within five working days.

Why it matters

Significant deviations affecting subject safety, rights, welfare, or data integrity must be reported to the IRB/EC and sponsor. Trends in deviations indicate a need for site retraining or protocol amendment.

Common pitfalls

•Failing to document minor deviations can obscure patterns indicating systemic issues or protocol flaws.
•Not assessing the impact of a deviation on subject safety or data integrity can lead to overlooking serious risks.
•Delaying the reporting of significant deviations can result in non-compliance and compromise study validity.
•Ignoring repeated deviations at a site may indicate inadequate training or a need for protocol clarification rather than isolated incidents.
•Misinterpreting which deviations require immediate reporting can lead to under-reporting or unnecessary administrative burdens.

Sources

Open full page

Select term B to compare.

Why compare MedTech terms side by side?

MedTech terminology is full of pairs that look interchangeable but carry very different regulatory, clinical, and commercial consequences. Picking the wrong framework, pathway, or standard early in a project can add months to a submission, invalidate clinical evidence, or trigger an audit finding. Side-by-side comparison is the fastest way to surface those differences before they become costly mistakes.

Each comparison on this page pulls from the same vendor-neutral, sourced definitions used throughout the MedTech Terms glossary. You see the one-line summary, the formal definition, why it matters in practice, common pitfalls, and the primary sources (FDA guidance, EU MDR/IVDR articles, ISO/IEC standards, MDCG documents, IMDRF principles) that back each entry. That makes the comparison defensible in regulatory strategy memos, design reviews, and submission narratives.

Common comparison patterns

Regulatory pathway choice - 510(k) vs PMA, 510(k) vs De Novo, Abbreviated vs Special 510(k).
Quality systems - QSR vs ISO 13485, QMSR vs QSR.
Software classification - SaMD vs SiMD, Locked vs adaptive AI.
EU frameworks - MDR vs IVDR, CE Mark vs UKCA.
Cybersecurity artifacts - SPDX vs CycloneDX SBOM, CVE vs CVSS.
Post-market actions - Recall vs field action, Removal vs correction.

How to use this tool

Pick term A and term B from the dropdowns, or click a preset above. The URL updates with both slugs so you can bookmark or share the exact comparison with a colleague, a notified body reviewer, or your regulatory consultant. Click Open full page on either side for the complete entry, including FAQs, related terms, and the full citation list. If you are not sure which term to start with, browse the Categories view or the A-Z index.

MedTech Terms is a vendor-neutral community resource sponsored by Blue Goat Cyber. Definitions are written for educational use and are not legal or regulatory advice.