In vitro diagnostics play a critical role in modern healthcare, guiding everything from routine screening to targeted therapy selection. Yet the regulatory environment surrounding these products has rarely been more dynamic. Manufacturers face evolving FDA IVD requirements in the United States, a demanding transition under Europe’s In Vitro Diagnostic Regulation (IVDR), and increasing expectations for quality systems and performance evidence. For organizations developing or distributing products governed by IVD regulations, understanding this changing landscape is essential for maintaining diagnostic device compliance and long-term market access.
Understanding How the FDA Regulates In Vitro Diagnostics
Under U.S. law, in vitro diagnostic products are defined as reagents, instruments, and systems intended for use in diagnosing disease or other conditions, and they are regulated as medical devices under the Federal Food, Drug, and Cosmetic Act. The FDA applies a risk-based classification framework, placing IVDs into Class I, II, or III based on the level of control needed to reasonably assure safety and effectiveness. That classification determines the appropriate premarket pathway.
Most IVDs reach the market through one of three pathways. Class II devices typically require a 510(k) premarket notification demonstrating substantial equivalence to a legally marketed predicate. Lower- to moderate-risk devices without a suitable predicate may qualify for the De Novo classification process, while high-risk Class III devices generally require Premarket Approval (PMA) supported by robust clinical evidence. The FDA also standardizes most 510(k) and De Novo submissions through its interactive eSTAR template, which is required for these submission types to help improve completeness and review efficiency.
Laboratory-Developed Tests: A Moving Target
Few areas illustrate the evolving nature of IVD regulations more clearly than laboratory-developed tests (LDTs). On May 6, 2024, the FDA issued a final rule amending the definition of “in vitro diagnostic products” to clarify that IVDs are considered medical devices even when manufactured by a laboratory. The rule also included a four-year phaseout of the agency’s longstanding enforcement discretion.
That rule was short-lived. On March 31, 2025, a federal district court vacated it, and on September 19, 2025, the FDA reverted to the previous regulatory language. Laboratories should continue monitoring FDA communications closely, as the regulatory framework for LDT oversight remains unsettled.
Quality System Expectations Under the QMSR
Quality system requirements for IVD manufacturers have also entered a new era. Effective February 2, 2026, the FDA’s Quality Management System Regulation (QMSR) amended 21 CFR Part 820 by incorporating the international standard ISO 13485:2016 by reference. The regulation applies to manufacturers involved in the design, manufacture, packaging, labeling, storage, installation, or servicing of finished medical devices and requires each manufacturer to establish and maintain a quality management system appropriate for its devices.
The transition involves more than updated terminology. The FDA has retired the Quality System Inspection Technique (QSIT) in favor of a revised inspection program, and there is no additional grace period beyond the effective date. Manufacturers should verify that design controls, risk management, document control, supplier oversight, and quality system processes are fully aligned with ISO 13485 requirements to remain inspection ready.
IVDR Considerations for the European Market
Companies pursuing global distribution must also account for Regulation (EU) 2017/746, the In Vitro Diagnostic Regulation (IVDR), which replaced the earlier IVDD and became applicable on May 26, 2022. The IVDR establishes a more rigorous, risk-based classification system, expands the role of Notified Bodies in conformity assessments, and introduces more extensive requirements for clinical evidence, technical documentation, traceability, and post market surveillance throughout the device lifecycle. Transitional timelines introduced through subsequent legislation continue to affect when legacy devices must fully comply, making it important for manufacturers to evaluate their product portfolios against the applicable deadlines as early as possible.
Validation Strategies and Performance Evidence
Across both the United States and Europe, regulators expect diagnostic products to be supported by strong analytical and clinical performance data. In the United States, premarket submissions must demonstrate that a device performs as intended, with the level of evidence based on the device’s classification and risk. Under the IVDR, performance evaluation, including scientific validity, analytical performance, and clinical performance, is a core lifecycle requirement.
A well-developed validation strategy connects the device’s intended use with clearly defined performance claims, establishes acceptance criteria before testing begins, and maintains traceable documentation from product development through post market surveillance.
Common Compliance Pitfalls
Many compliance challenges continue to center around a few common issues. Misclassifying a device can lead manufacturers down the wrong regulatory pathway and result in unnecessary delays or costly rework. Incomplete or poorly organized submissions can slow regulatory review and, in the United States, can often be avoided by fully utilizing the structured eSTAR submission format. Treating the QMSR transition as simply a documentation update rather than a full alignment with ISO 13485 may expose manufacturers to compliance issues during inspection. Likewise, assuming FDA and IVDR requirements are interchangeable overlooks the IVDR’s unique classification framework and performance evidence expectations. Building a regulatory strategy early and revisiting it as requirements evolve remains one of the most effective ways to support long-term compliance.
Conclusion
The regulatory landscape for in vitro diagnostics continues to evolve with an unsettled framework for laboratory-developed tests, implementation of the FDA’s Quality Management System Regulation, and the continued maturation of the IVDR in Europe. Meeting FDA IVD requirements while satisfying global regulatory obligations requires proactive planning, strong performance evidence, and quality systems designed for continuous compliance. Organizations that treat IVD regulations as a strategic priority rather than a last-minute requirement are better positioned for smoother regulatory reviews, stronger diagnostic device compliance, and faster patient access to reliable diagnostic tests.
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References
- U.S. Food and Drug Administration. Overview of IVD Regulation. [fda.gov]
- U.S. Food and Drug Administration. eSTAR Program. [fda.gov]
- U.S. Food and Drug Administration. Laboratory Developed Tests. [fda.gov]
- Federal Register. Medical Devices; Laboratory Developed Tests (Final Rule, 89 FR 37286). [federalregister.gov]
- U.S. Food and Drug Administration. Quality Management System Regulation (QMSR). [fda.gov]
- Electronic Code of Federal Regulations. 21 CFR Part 820 – Quality Management System Regulation. [ecfr.gov]
- EUR-Lex. Regulation (EU) 2017/746 on In Vitro Diagnostic Medical Devices (IVDR). [eur-lex.europa.eu]