The FDA had cleared more than 700 AI-enabled medical devices through three distinct pathways as of 2025. The regulatory mechanism determines not only whether a device can be sold but what clinical claims its manufacturer can make and how much post-market surveillance is required. Understanding the difference between 510(k), De Novo, and PMA matters for anyone evaluating AI medical devices for clinical deployment.
The 510(k) Pathway
The 510(k) pathway requires a manufacturer to demonstrate substantial equivalence to a legally marketed predicate device: that the new device has the same intended use and technological characteristics as the predicate, or different characteristics that do not raise different questions of safety and effectiveness and that performance data show are as safe and effective as the predicate. Most AI medical device clearances in the United States come through 510(k). The evidentiary bar is substantial equivalence, not superiority, and the specific evidence required varies by device and by how closely it resembles its predicate: many submissions rely on bench performance testing and retrospective validation data against the predicate’s cleared claims, without a full prospective clinical trial, but the FDA can and does require clinical performance data for 510(k) submissions where the device’s risk profile, novel technological characteristics, or algorithm changes warrant it. “No clinical trials required” is a common shorthand that oversimplifies a standard that is substantial-equivalence-based and device-specific, not a blanket exemption from clinical evidence.
The De Novo Pathway
When no suitable predicate exists, manufacturers can request De Novo classification. The FDA evaluates the novel device against a risk-based standard and, if granted, the De Novo decision itself becomes a predicate for future 510(k) submissions. The first AI device cleared through De Novo for a given indication creates the template for subsequent clearances in that category.
The PMA Pathway
Premarket Approval applies to the highest-risk devices and requires valid scientific evidence, typically clinical trials, demonstrating reasonable assurance of safety and effectiveness. PMA is rare for AI medical devices. The clinical trial requirement is expensive and slow relative to 510(k). Most AI device manufacturers structure their submissions to qualify for 510(k) rather than PMA.
The EU AI Act Comparison
The EU AI Act classifies most medical AI as high-risk and requires conformity assessment, registration in an EU database, and post-market monitoring plans. The March 2026 European Radiology review documented convergence between FDA, EU, and China NMPA frameworks on core requirements including performance testing, bias evaluation, and transparency, with meaningful differences in stringency and enforcement.
Limitations
FDA clearance establishes safety and effectiveness relative to a predicate, not superiority over current standard of care. A cleared AI device may be no better than existing tools; clearance does not mean clinically beneficial. Post-market surveillance requirements for cleared AI devices are less rigorous than those applied to high-risk drugs.
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Primary sources: FDA AI/ML medical device database; March 2026 European Radiology review of international AI medical device frameworks. Updated 2026-08-18: replaced the categorical “does not require clinical trials” claim about 510(k) with the actual substantial-equivalence standard, since evidence requirements are device-specific and the FDA can require clinical performance data for higher-risk or more novel 510(k) submissions.