510(k) vs De Novo: How to Choose the Right FDA Pathway

The 510(k) and De Novo pathways both lead to legal marketing authorization for Class II medical devices. The fundamental difference is whether a legally marketed predicate exists. If it does, 510(k) is the appropriate pathway. If it doesn't — or if the device is novel enough that substantial equivalence cannot be established — De Novo is the correct route.

When 510(k) is the right choice

510(k) is appropriate when you can identify at least one legally marketed predicate with the same intended use and substantially similar or acceptably different technological characteristics. For devices in established categories — monitoring equipment, surgical instruments, diagnostic tools with long clearance histories — 510(k) is almost always the faster and less expensive path.

The key question to ask: can I find a cleared device that does essentially the same thing as my device? If yes, start with 510(k). If the answer requires significant qualification — "it's similar, but the intended use is slightly different" or "it uses similar technology for a different indication" — the predicate may not hold up under FDA scrutiny.

When De Novo is appropriate

De Novo is appropriate for novel devices that don't fit existing device types — but for which the risk profile supports Class II classification rather than PMA. The core question FDA evaluates in a De Novo request is whether general controls and special controls (which the applicant proposes) can provide reasonable assurance of safety and effectiveness.

De Novo is most commonly used for: software-driven devices with novel intended uses, combination devices that don't fit existing product codes, diagnostic tests for previously untested biomarkers, and devices using novel technologies (new materials, new sensing modalities, new therapeutic mechanisms) that have no predicate in any existing device category.

The strategic value of De Novo

A successful De Novo classification creates a new generic device type with a new product code and new special controls. Critically, the De Novo-classified device becomes itself a predicate for future 510(k) submissions by anyone — including competitors.

This means that a company that pursues De Novo for a novel device type bears the full regulatory burden of establishing the pathway — but also gets to shape the special controls that will govern their product category. Competitors who follow with 510(k) submissions citing your De Novo as a predicate can move faster, but they are subject to the special controls you helped establish.

The NSE-then-De Novo sequence

Historically, De Novo was primarily used after a 510(k) received a Not Substantially Equivalent determination. FDA has updated this — applicants can now file De Novo directly without a prior 510(k) if they determine upfront that no valid predicate exists. The direct De Novo route is generally faster than the NSE-then-De Novo path because it avoids the 510(k) review period.

If you are filing a 510(k) and you are uncertain whether a valid predicate exists, consider whether a direct De Novo application might be more efficient. The predicate research you would do for a 510(k) is also necessary for a De Novo — the difference is that De Novo asks you to establish the special controls yourself rather than relying on an existing predicate's regulatory basis.