Drugdu.com expert's response:

Under the EU Medical Device Regulation (Regulation (EU) 2017/745), the classification of medical devices is primarily based on their intended use and inherent risks, following a detailed set of classification rules that categorize medical devices into four classes: Class I, Class IIa, Class IIb, and Class III. Below are the core principles and logic of this classification system:

I. Core Principles of Classification

Risk Stratification: The higher the risk level, the stricter the classification and regulatory requirements.

Intended Use as the Primary Factor: Classification is based on the manufacturer's declared intended use, without considering misuse or abuse scenarios.

Highest Risk Applies When Multiple Rules Apply: If a single device is subject to multiple classification rules, it is classified according to the rule with the highest risk.

Key Factors: Invasiveness, Duration of Use, Active/Non-Active, and Site of Action:

Invasiveness: Non-invasive, through body orifices, surgical invasive, implantable.

Duration of Use: Transient (<60 minutes), short-term (60 minutes to 30 days), long-term (>30 days).

Active/Non-Active: Dependent on electrical energy or external power sources (e.g., software).

Site of Action: High-risk sites such as the heart, central circulatory system, and central nervous system directly elevate the device to Class III.

II. Detailed Classification Rules

Non-Invasive Devices (Rules 1-4)

Rule 1: All non-invasive devices are classified as Class I by default, unless they are intended for the delivery/storage of blood, body fluids, or cells (e.g., infusion sets, blood collection tubes), in which case they are classified as Class IIa.

Rule 2: Non-invasive devices intended to alter biological or chemical composition (e.g., dialysis equipment) are classified as Class IIb.

Rules 3-4: Non-invasive devices with special purposes (e.g., sterilization devices) are classified according to the rules.

Invasive Devices (Rules 5-8)

Rule 5: Devices that are invasive through body orifices but not surgically invasive and not connected to an active device or only connected to a Class I active device are classified as Class I for transient use (e.g., oral mirrors) and Class IIa for long-term use (e.g., ear canal thermometers).

Rule 6: Surgically invasive devices are classified as Class IIa for transient use (e.g., surgical knives) and Class IIb for long-term use (e.g., joint implants).

Rule 7: Implantable devices (remaining in the body for ≥30 days post-surgery) are classified as Class IIb (e.g., cardiac pacemakers), or Class III if involving high-risk sites (e.g., central nervous system).

Rule 8: Invasive devices related to body orifices, if connected to Class IIa/IIb/III active devices, are classified as Class IIa (e.g., catheter combined with a pump).

Active Devices (rules 9-13)

Rule 9: Active therapeutic devices (e.g., laser surgical equipment) are classified as Class IIb, or Class III if involving high-risk sites.

Rule 10: Active diagnostic/monitoring devices (e.g., electrocardiographs) are classified as Class IIa, or Class IIb if providing critical diagnostic information.

Rules 11-13: Special active devices (e.g., drug delivery devices, closed-loop systems) are classified according to the rules.

Special Rules (rules 14-22)

Rules 14-16: Contraceptive devices, sterilization devices, radiodiagnostic devices, etc., are classified according to dedicated rules.

Rules 17-22: Devices involving emerging technologies such as software, combination products, and nanomaterials are classified according to the rules.

III. Practical Steps for Classification

Determine Intended Use: Clearly define the primary function and usage scenario of the device.

Identify Key Characteristics:

Is it invasive?

What is the duration of use (transient/short-term/long-term)?

Does it rely on electrical energy or external power sources?

Is the site of action high-risk (e.g., heart, central nervous system)?

Apply Classification Rules: Match the characteristics to the rules and select the highest risk rule if multiple rules apply.

Verify Classification Results: Refer to examples and guidelines in Annex VIII of the MDR (e.g., MDCG 2021-24 Rev.1).

IV. Regulatory Impact of Classification

Class I: Low risk; manufacturers self-declare conformity without the involvement of a notified body.

Class IIa: Medium risk; requires notified body review of technical documentation and may require clinical data.

Class IIb: High risk; requires comprehensive notified body review, including clinical evaluation and post-market surveillance.

Class III: Extremely high risk; requires rigorous clinical trials and continuous regulatory oversight, such as artificial heart valves.

V. Latest Revision Updates

2026 Revision: The EU has released a new version of the classification guidelines (MDCG 2021-24 Rev.1), clarifying the classification rules for emerging technologies such as AI medical devices, wearable devices, and software as a medical device (SaMD). It also refines the time definitions for invasive devices (e.g., "transient," "short-term," "long-term").

Effective Date: From October 20, 2026, all new applications must be classified according to the new guidelines; for already marketed products, if their classification changes, compliance rectification must be completed by April 20, 2027.