The 22 classification rules
Schedule 2 of the Medicines (Database of Medical Devices) Regulations 2003 sets out 22 rules for classifying non-IVD medical devices. Rules are grouped into four categories.
Applying the rules
Apply all potentially relevant rules to your device. If more than one rule gives a different classification, the highest class applies.
Rules 1–4 — Non-invasive devices
| Rule | Summary | Default class |
|---|---|---|
| Rule 1 | All non-invasive devices not covered by Rules 2–4 | Class I |
| Rule 2 | Channelling or storing blood, body fluids, cells, or liquids for infusion | Class IIa |
| Rule 3 | Modifying biological or chemical composition of blood, tissues, or cells; or in contact with injured skin | Class IIa or IIb depending on intended use |
| Rule 4 | Contact with injured skin as a wound dressing | Class I, IIa, or IIb depending on depth and condition |
Rules 5–8 — Invasive devices
| Rule | Summary | Default class |
|---|---|---|
| Rule 5 | Invasive devices for body orifices — transient use | Class I |
| Rule 6 | Invasive devices for body orifices — short-term use; surgically invasive transient devices | Class IIa |
| Rule 7 | Surgically invasive devices — short-term use | Class IIa or IIb |
| Rule 8 | Implantable devices and long-term surgically invasive devices | Class IIb or III |
Rules 9–12 — Active devices
| Rule | Summary | Default class |
|---|---|---|
| Rule 9 | Active therapeutic devices intended to exchange energy | Class IIa or IIb |
| Rule 10 | Active devices for diagnosis | Class IIa (with some Class I and IIb exceptions) |
| Rule 11 | Software intended to provide information for diagnosis or treatment decisions | Class IIa (or higher if failure could be catastrophic) |
| Rule 12 | Active devices intended to administer or exchange energy in a potentially hazardous way | Class III |
Rules 13–18 — Special rules
| Rule | Summary | Class |
|---|---|---|
| Rule 13 | Devices incorporating a medicinal substance | Class III |
| Rule 14 | Devices used for contraception or STI prevention | Class IIb or III |
| Rule 15 | Devices specifically intended for disinfection of other medical devices | Class IIa or IIb |
| Rule 16 | Devices specifically for recording X-ray images | Class IIa |
| Rule 17 | Devices manufactured from biological origin (animal tissue or derivatives) | Class III |
| Rule 18 | Blood bags | Class IIb |
Rules 19–22 — Additional rules
| Rule | Summary | Class |
|---|---|---|
| Rule 19 | AIMDs — active implantable medical devices | AIMD class |
| Rule 20 | Devices that incorporate a substance that, used separately, would be a medicinal product and has action ancillary to the device | Class III |
| Rule 21 | Devices used for birth control or STI prevention (not covered by Rule 14) | IIb |
| Rule 22 | Nanomaterial-based devices | Depends on intended use and potential for internal exposure |
Worked example
Device: A single-use catheter inserted through the urethra for a procedure lasting approximately 45 minutes.
- Is it non-invasive? No — it enters a body orifice
- Rule 5 — invasive, body orifice, transient use (≤60 min) → Class I
- But Rule 6 — short-term (>60 min, ≤30 days) would give IIa
- Duration is ~45 min → transient → Rule 5 → Class I
If the same catheter was left in for 2 hours, it would fall under Rule 6 → Class IIa.
Official guidance
For complex classification decisions, consult the Medsafe guidance document on classification and the GHTF/SG1/N015:2006 guidance on medical device classification, which Medsafe references in its framework.