The Lesson Before the Rule
Here is the practical lesson buried in this Federal Register notice: if you are developing a novel in vitro diagnostic and you assume it will land in Class III by default, you may be leaving a faster, cheaper pathway on the table. FDA's June 1, 2026 final order classifies the von Willebrand factor assay into Class II, subject to special controls. It's a case study in how the De Novo pathway under section 513(f)(2) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) actually works. And it's a roadmap for any manufacturer sitting on a diagnostic device with no existing classification regulation to point to.
I've watched clients default to assuming "novel means PMA" for years — a defensible starting point, but not a life sentence. This order shows FDA using the statutory tool built specifically to correct it.
What Actually Changed
FDA published the final order titled "Medical Devices; Hematology and Pathology Devices; Classification of the Von Willebrand Factor Assay" in the June 1, 2026 Federal Register (document 2026-10898). The order classifies the von Willebrand factor assay — a laboratory test used to help diagnose von Willebrand disease, the most common inherited bleeding disorder — into Class II, subject to special controls, and it amends 21 CFR Part 864, the section of the Code of Federal Regulations governing hematology and pathology devices.
Before this order, a von Willebrand factor assay seeking market authorization for the first time had no dedicated classification regulation to rely on. Under section 513(f)(1) of the FD&C Act, a device with no predicate and no existing classification is automatically regulated as Class III. That means a Premarket Approval (PMA) application under 21 CFR Part 814: full clinical data, FDA advisory panel exposure in many cases, and a review process built for high-risk devices like implantable defibrillators — not coagulation screening assays run in a hospital lab.
That is where the De Novo pathway comes in. Section 513(f)(2) of the FD&C Act lets a sponsor petition FDA to reclassify a novel low-to-moderate-risk device into Class I or Class II instead of leaving it in Class III, provided general controls — or general controls plus special controls — give reasonable assurance of safety and effectiveness. The process itself is codified at 21 CFR 860.34. FDA's order states plainly that it took this action "because we have determined that classifying the device into class II will provide a reasonable assurance of safety and effectiveness of the device" — the statutory standard the agency has to meet every time it grants a De Novo request.
A device that FDA classifies into Class II through the De Novo pathway becomes a legal predicate that later manufacturers can cite in their own 510(k) submissions. That's the real prize here, and it's easy to miss if you only read the headline.
Why This Matters for Von Willebrand Disease Diagnostics
Classification isn't an abstract regulatory detail for this device type — it's tied directly to patient safety. A misclassified or poorly validated VWF assay doesn't just produce a wrong lab value on a chart. It can lead a clinician to clear a patient for surgery who actually has a bleeding risk, or to withhold prophylactic treatment before a procedure based on a falsely reassuring result.
That risk exists because von Willebrand disease is diagnostically complex. It's caused by a deficiency or dysfunction of von Willebrand factor, a glycoprotein that helps platelets stick together at sites of vessel injury and stabilizes clotting Factor VIII in circulation. Labs diagnose and monitor it using several assay formats — von Willebrand factor antigen (VWF:Ag), activity assays historically run as ristocetin cofactor (VWF:RCo) and increasingly as newer platelet glycoprotein Ib–binding methods, and collagen-binding assays (VWF:CB) — often run together as a panel because no single assay reliably captures every disease subtype.
Von Willebrand disease is the most common inherited bleeding disorder in humans. Yet the assay used to diagnose it had never before had its own dedicated device classification under 21 CFR Part 864 — which meant every new entrant had to either find an imperfect predicate for a 510(k) or absorb the cost of a full PMA.
What the Special Controls Typically Address
FDA's order codifies special controls specific to this device type rather than pointing to a separate guidance document, but the codified regulation text under 21 CFR Part 864 was not yet published as of this writing. Based on the pattern FDA has followed in comparable hematology De Novo orders, manufacturers should expect the special controls to address these core categories — confirm the exact language in the codified regulation before finalizing your validation package:
- Analytical performance validation — accuracy, precision (repeatability and reproducibility), analytical sensitivity, analytical specificity and interference testing (from substances like hemolysis, lipemia, and common anticoagulants), and the assay's reportable range.
- Clinical validation — method comparison against an appropriate reference method or clinically confirmed von Willebrand disease diagnoses, across disease subtypes where the assay is intended to differentiate them.
- Labeling — a clearly stated intended use, warnings about the assay's limitations (particularly for detecting certain type 2 variants or low VWF levels), and instructions that the result must be interpreted alongside clinical presentation and other coagulation testing, not in isolation.
- Design controls and risk management documentation consistent with the manufacturer's quality system — see ISO 13485:2016 Clause 7.3 (design and development) — showing that failure modes affecting result accuracy were identified and mitigated before the device reached the market.
This is the same architecture FDA uses across most De Novo special-controls orders for laboratory diagnostics: instead of requiring the exhaustive premarket clinical burden of a PMA, FDA locks in the specific analytical and clinical validation studies it considers necessary, then lets future manufacturers demonstrate substantial equivalence to this classification through the 510(k) pathway under 21 CFR 807.
Classification Pathways Compared
| Factor | Class III (PMA, 21 CFR 814) | Class II via De Novo (this order) | Class II via 510(k) (post-order, 21 CFR 807) |
|---|---|---|---|
| Statutory basis | FD&C Act § 515 | FD&C Act § 513(f)(2); 21 CFR 860.34 | FD&C Act § 510(k) |
| Predicate device required | No | No — creates the predicate | Yes — can now cite this order |
| Evidence standard | Full safety and effectiveness data, often clinical trials | General controls + special controls named in the order | Substantial equivalence to a predicate meeting the special controls |
| Who uses this pathway for VWF assays now | No one, going forward, for this device type | The original De Novo requester | Every subsequent manufacturer of a von Willebrand factor assay |
| Governing CFR part for the device itself | 21 CFR 814 | 21 CFR Part 864 (new classification regulation) | 21 CFR Part 864, referencing the special controls |
The practical shift: a manufacturer bringing a second-generation or competing von Willebrand factor assay to market no longer has to petition for its own De Novo review or justify Class III status. It can file a 510(k), point to this classification, and build its submission around the special controls FDA has already specified.
Compliance Guidance: What Manufacturers Need to Do Now
If you manufacture, or are developing, a von Willebrand factor assay, here is what this order actually requires of you going forward.
1. Confirm your product code and classification status. Once FDA finalizes a De Novo order, the agency assigns a product code and classification regulation specific to that device type. Any new von Willebrand factor assay entering the U.S. market should be filed against this classification rather than treated as an unclassified novel device.
2. Build your validation package around the named special controls, not around what a competitor did. The special controls in the order are the floor, not a suggestion. Your analytical validation — precision, sensitivity, specificity, interference, reportable range — and your clinical validation against confirmed von Willebrand disease cases need to map directly to what the classification order specifies, documented as part of your design verification and validation records.
3. Treat this as a design controls exercise, not just a submission exercise. Special controls tied to a Class II classification aren't satisfied by paperwork at the time of submission. They have to be built into your design history file from the start: design inputs that reference the specific performance criteria (ISO 13485:2016 Clause 7.3.3), verification and validation testing that demonstrates you met them (Clause 7.3.6–7.3.7), and a risk management file under ISO 14971 that shows you identified and mitigated the failure modes FDA cares about. Our design controls resource maps design history file structure to what a classification order like this one requires.
4. Don't skip the 510(k) just because a classification exists. Existing on a classification list doesn't authorize marketing — you still need clearance. Manufacturers planning a 510(k) submission for a von Willebrand factor assay should route their premarket strategy through a structured FDA 510(k) process that accounts for the special controls as the substantial equivalence baseline, not an afterthought.
5. Keep your quality system current with the QMSR transition. FDA's Quality Management System Regulation, which incorporates ISO 13485:2016 by reference and replaces the former 21 CFR Part 820 quality system regulation, has a compliance date of February 2, 2026. Any design control and risk management work you're doing to satisfy this classification's special controls should already be built against QMSR clause structure, not the legacy Part 820 framework, since inspections after that date will be conducted against the harmonized standard.
Effective Date
This order is effective June 1, 2026, per its publication in the Federal Register as document 2026-10898. There is no grandfathering provision for devices that were never legally marketed. A device already on the market under an existing legal pathway — for example, an assay cleared previously under a different, related classification — should confirm with regulatory counsel whether this new, more specific classification changes its own regulatory status. It should also confirm the codified special controls text against 21 CFR Part 864 once that text publishes.
Why FDA Uses This Mechanism
It's worth asking why FDA relies on De Novo classification at all rather than routing every novel device down the same review track. The honest answer is efficiency on both sides of the desk.
A full Premarket Approval review demands far more clinical evidence and agency review time than a 510(k) built on defined special controls. FDA doesn't have the bandwidth to run every moderate-risk diagnostic through that process, and manufacturers of genuinely lower-risk devices shouldn't have to absorb PMA-level costs for a well-understood assay type. The De Novo pathway exists to close that gap between actual device risk and the regulatory burden the statute would otherwise impose.
What This Doesn't Do
A Class II classification with special controls is not a lighter version of due diligence — it's a more specific one. FDA has told manufacturers exactly what it wants to see, which removes ambiguity but doesn't reduce the underlying testing burden by much. I'd also flag that "special controls" named in an order are not exhaustive of everything a reasonable quality system should do — they're the floor FDA considers necessary for that specific risk profile, not a ceiling on your own risk management obligations under your quality system.
FAQ
What is a von Willebrand factor assay, and why did it need its own classification? It's a laboratory test that measures the level or activity of von Willebrand factor, a blood protein used to diagnose and monitor von Willebrand disease. Before this order, it had no dedicated classification regulation under 21 CFR Part 864, which meant every new version had to clear the market through a full PMA rather than a 510(k).
What does "Class II with special controls" mean in practice? It means the device no longer requires a Premarket Approval application. Instead, manufacturers demonstrate compliance with the specific special controls named in FDA's order — covering analytical performance, clinical validation, and labeling — typically through a 510(k) submission under 21 CFR Part 807.
Does this classification apply retroactively to assays already on the market? The order does not grandfather existing devices differently based on when they were marketed; it establishes the classification and special controls going forward. Manufacturers with an existing von Willebrand factor assay should confirm with regulatory counsel how the new classification interacts with their device's current legal marketing status.
How is this different from a device going through a standard 510(k)? A standard 510(k) requires an existing predicate device. Before this order, there was no predicate for a von Willebrand factor assay classification, so the original request had to go through the De Novo pathway under FD&C Act section 513(f)(2) and 21 CFR 860.34 to create one. Every subsequent manufacturer can now use a standard 510(k) referencing this classification.
Does this classification change ISO 13485 or QMSR obligations for manufacturers? No — general quality system obligations are separate from device classification. But the special controls named in this order have to be satisfied through your design control and risk management processes, which FDA now evaluates against the QMSR (incorporating ISO 13485:2016), with a compliance date of February 2, 2026.
Last updated: 2026-08-19
Jared Clark
Principal Consultant, Certify Consulting
Jared Clark is the founder of Certify Consulting, helping organizations achieve and maintain compliance with international standards and regulatory requirements.