Software as a Medical Device (SaMD)
Definition
Software as a Medical Device (SaMD) is software intended to be used for one or more medical purposes that perform these purposes without being part of a hardware medical device. FDA adopted this definition from the IMDRF SaMD Key Definitions (N12) document.
A SaMD must:
- Perform a medical purpose (diagnosis, monitoring, treatment, prevention of a disease or condition)
- Do so without being part of a hardware device (software embedded in or controlling a hardware device is not SaMD — it is device software functions or a part of the hardware device)
Is my software a medical device?
FDA's Software Functions Guidance (2023) establishes a three-category framework:
| Category | Description | FDA regulated? |
|---|---|---|
| Device software functions | Software that meets the FD&C Act § 201(h) device definition | Yes |
| Non-device software functions | Software excluded from the device definition (administrative, general wellness, EHR, data transfer only) | No |
| Exempt CDS | Clinical decision support that is not the primary basis for a clinical decision and whose basis can be independently reviewed | No (excluded by § 520(o)) |
SaMD risk framework
FDA applies a risk-based approach to SaMD, aligned with the IMDRF SaMD Risk Categorisation Framework (N23):
| SaMD Risk | State of healthcare situation | Significance of information |
|---|---|---|
| IV (highest) | Critical | Driving clinical management |
| III | Serious | Driving clinical management |
| II | Non-serious | Driving clinical management |
| I (lowest) | Any | Informing clinical management |
Higher-risk SaMD (Risk Categories III and IV) typically requires a more rigorous premarket review pathway (PMA or De Novo rather than 510(k)) and substantial clinical evidence, including head-to-head performance studies against applicable reference standards.
SaMD classification
SaMD is classified under the same Class I/II/III system as all other devices, using the same product codes and classification regulations. Common SaMD classifications:
| SaMD type | Typical class | Typical pathway |
|---|---|---|
| AI-based diagnostic imaging software | II or III | 510(k) or De Novo |
| Glucose monitoring app (CGM companion) | II | 510(k) |
| AI/ML-based ECG interpretation | II | De Novo or 510(k) |
| High-risk diagnostic AI (novel) | III | PMA |
| CDS software meeting § 520(o) exemption | Not a device | No submission |
Key FDA guidance for SaMD
| Document | Year | Key content |
|---|---|---|
| Software Functions: Device vs Non-Device | 2023 | Determines if software is a device under § 520(o) |
| Clinical Decision Support Software | 2022 | Boundaries of exempt CDS |
| Artificial Intelligence/Machine Learning Action Plan | 2021 | FDA's approach to AI/ML-based devices |
| Predetermined Change Control Plans | 2024 | Framework for managing AI/ML algorithm changes |
| Software as a Medical Device: Clinical Evaluation | 2017 | Aligns with IMDRF N41 |
Official resources
Key distinction: SaMD is standalone software that performs medical functions independently. Device software functions are software embedded within or controlling a hardware device (e.g., firmware in an infusion pump, algorithms in a ventilator). Both are regulated, but device software functions are regulated as part of the hardware device classification, not as separate SaMD.