Classification rules — Schedule 2 in detail

Regulatory basis

The 18 classification rules for general medical devices are in Schedule 2 of the UK MDR 2002 (Part I). These rules are applied by the manufacturer and reviewed by a UKAB where conformity assessment requires third-party involvement. Where multiple rules produce different classes, the highest class prevails.

Disclaimer

This site provides general information only and does not constitute legal or regulatory advice. Classification decisions are the manufacturer's responsibility and should be documented with a detailed rationale.

Key definitions used across the rules

Before applying the rules, establish the following for your device:

Term	Definition
Invasive device	Penetrates the body surface (skin, mucosa) or enters through a body orifice
Surgically invasive device	Invasive device introduced into the body via a surgical incision
Implantable device	Intended to be totally introduced into the body or replace epithelial/ocular surface, remaining after the procedure
Active device	Depends on a source of electrical energy or other source of power other than generated by the human body or gravity
Active therapeutic device	Active device used to treat or alleviate a disease, injury, or disability
Active device for diagnosis	Active device used to detect, monitor, or diagnose disease, injury, or disability
Transient use	Intended for continuous use < 60 minutes
Short-term use	Intended for continuous use 60 minutes to 30 days
Long-term use	Intended for continuous use > 30 days
Central circulatory system	Aorta, pulmonary arteries/veins, coronary arteries, carotid arteries, cerebral arteries, and other major vessels
Central nervous system	Brain, meninges, spinal cord

Rules 1–4: Non-invasive devices

Rule 1 — Default: Class I

All non-invasive devices are in Class I unless another rule applies.

This is the starting rule. If no other rule creates a higher class, a non-invasive device is Class I.

Examples: tongue depressors, bandages, non-sterile examination gloves, hospital beds, reading glasses frames.

Rule 2 — Channelling or storing blood, body liquids, or tissues

Non-invasive devices intended for channelling or storing blood, body liquids, organs, or tissues are classified as follows:

Class IIa if intended for use with active medical devices (Class IIa or higher), or intended for storage of blood or other body liquids or storage of organs under conditions that may cause clinically significant biological alteration
Class I in all other cases

Class IIa examples: blood bags, blood transfusion sets, cell storage containers at non-standard temperatures Class I examples: specimen containers for standard room-temperature storage, non-active urine collection bags

Rule 3 — Skin, wound, or mucosa contact

Non-invasive devices intended to modify the biological or chemical composition of blood, other body liquids, or other liquids intended for infusion into the body:

Class IIb if intended for use with blood or other body liquids, where the treatment can cause biological alteration
Class IIa if contact is with modified liquids intended for subsequent infusion

Class IIb examples: haemofilters, plasmapheresis filters, cardiopulmonary bypass circuits

For wound or mucosa contact:

Class IIa if intended to be used primarily with wounds which have breached the dermis and can only heal by secondary intent (chronic wounds)
Class I in all other cases

Class IIa wound examples: chronic wound dressings, burns dressings (deep partial/full thickness) Class I examples: plasters, simple wound dressings for superficial wounds

Rule 4 — Devices in contact with injured skin

All non-invasive devices which come into contact with injured skin:

Class IIb if intended for use as a barrier or for compression/absorption of wound exudate for deep wounds or wounds healing by secondary intent
Class IIa if intended to manage the micro-environment of a wound
Class I in all other cases

Rules 5–8: Invasive devices

Rule 5 — Body orifice invasive devices (transient)

All invasive devices intended to enter through a body orifice (not surgically invasive):

Class IIa if intended for connection to an active medical device (Class IIa or higher)
Class I if transient use

Class IIa examples: tracheal suction catheters used with suction devices Class I examples: auriscope specula, single-use nasal specula

Rule 6 — Body orifice invasive devices (short-term)

Invasive devices through body orifices, intended for short-term use:

Class IIa as the default
Class III if used in the oral cavity and absorbed by the mucous membrane
Class IIa for all other applications

Class IIa examples: urinary catheters (≤30 days), short-term tracheal tubes, gastric tubes Class III examples (absorbed): absorbable sutures in oral cavity

Rule 7 — Body orifice invasive devices (long-term)

Invasive devices through body orifices, long-term use:

Class IIb as default
Class III if they are intended to be used in direct contact with the heart, central circulatory system, or central nervous system

Class IIb examples: long-term urinary catheters, long-term tracheal tubes Class III examples: long-term CNS drainage catheters

Rule 8 — Surgically invasive devices (transient use)

Surgically invasive devices intended for transient use:

Class IIa as default
Class III if:
- intended specifically to control, diagnose, monitor or correct a defect of the heart or central circulatory system through direct contact with those parts
- intended to be used in direct contact with CNS
- supplied in sterile condition and not intended to be reused

Class IIa examples: surgical scalpels, needles, disposable surgical instruments (sterile) Class III examples: intraoperative cardiac mapping catheters

Note: Reusable surgical instruments are Class I (with Im sub-category for the reprocessing aspects).

Rule 9 — Surgically invasive devices (short-term)

Surgically invasive devices intended for short-term use:

Class IIa as default
Class IIb if intended:
- to be used in direct contact with the heart, central circulatory system, or CNS
- to supply energy in the form of ionising radiation
- to have a biological effect (other than listed above)
- to undergo chemical change in the body (other than in teeth)
- to administer medicines
Class III if intended to be placed in the teeth

Class IIa examples: short-term drainage catheters, anastomosis clips Class IIb examples: short-term coronary perfusion catheters

Rule 10 — Active implantable devices

All surgically invasive devices intended for long-term use are:

Class IIb as default
Class III if intended to:
- be placed in the teeth
- be used in direct contact with the heart, central circulatory system, or CNS
- have biological effect or to be wholly or mainly absorbed
- undergo chemical change in the body (except in teeth)
- administer medicines
- be implantable active devices (→ Part II AIMD)

Class IIb examples: orthopaedic plates, screws, rods (non-cemented), sutures Class III examples: cardiac valve replacements, coronary stents, spinal cord stimulators

Rules 9–12: Active devices

Rule 11 — Active therapeutic devices

Active therapeutic devices intended to administer or exchange energy:

Class IIa as default
Class IIb if the exchange of energy could be hazardous, taking into account the nature, density, and site of application of the energy
Class III if intended to administer energy to the human body in a potentially hazardous way, e.g.:
- delivering significant power
- in contact with CNS or central circulatory system

Class IIa examples: electro-surgical generators (low power), TENS machines, therapeutic ultrasound, phototherapy for neonatal jaundice Class IIb examples: high-intensity lasers, radiotherapy planning systems (active device aspects) Class III examples: cardiac defibrillators, external cardiac pacemakers

Rule 12 — Active diagnostic devices

Active devices intended for diagnosis:

Class IIa if:
- intended to supply energy to the human body (e.g., X-ray for imaging)
- intended to image the distribution of radio-pharmaceuticals in vivo
- intended for direct diagnosis or monitoring of vital physiological processes — unless specifically used for monitoring vital physiological parameters where the nature of variations could result in immediate danger to the patient, in which case Class IIb
Class IIb if intended for use with Class IIb or III active therapeutic devices, or for controlling such devices
Class I if intended to illuminate the patient's body with visible radiation

Class IIa examples: ultrasound diagnostic scanners, X-ray equipment (diagnostic), pulse oximeters (routine monitoring) Class IIb examples: cardiac monitors with life-critical alerting, EEG/ECG systems for acute monitoring, software controlling Class IIb therapy Class I examples: examination lights, surgical headlights

Software note: Software that functions as an active diagnostic device falls primarily under Rule 12. The clinical significance of the output and the potential for immediate danger drive classification between Class IIa and IIb. See Software & SaMD classification.

Rules 13–18: Special rules

Rule 13 — Devices incorporating medicinal substances

All devices incorporating, as an integral part, a substance which, if used separately, would be a medicinal product, and which is liable to act on the human body with an action ancillary to that of the device:

Class III in all cases

Examples: antibiotic-impregnated catheters, drug-eluting stents, bone cement with antibiotic

Rule 14 — Devices used for contraception or prevention of STIs

Class IIb if not implantable
Class III if implantable or intended for long-term use

Class IIb examples: condoms, diaphragms Class III examples: IUDs, contraceptive implants

Rule 15 — Devices specifically for disinfecting, cleaning, rinsing, or hydrating contact lenses

Class IIb in all cases

Examples: contact lens cleaning solutions, contact lens storage solutions

Rule 16 — Non-active devices specifically intended for recording diagnostic images

Class IIa in all cases

Examples: X-ray film, imaging plates for digital X-ray (non-active components)

Rule 17 — Devices using animal tissues or cells or their derivatives

Devices manufactured utilising animal tissues or cells rendered non-viable or non-viable derivatives of animal tissues:

Class III in all cases except:
- devices intended to come into contact with intact skin only → Class I

Class III examples: porcine heart valves, bovine collagen implants, animal-derived wound dressings contacting non-intact skin Class I examples: animal-derived leather straps on non-invasive devices

Rule 18 — Blood bags

Class IIb in all cases

Examples: blood collection bags, component bags for blood banking

Applying multiple rules — the highest-class-prevails principle

When classifying a device, apply all relevant rules and identify the resulting class for each. Where rules produce different classes:

The device is classified in the higher class.

Example: An active, sterile, short-term surgically invasive infusion pump component that also administers a medicinal substance:

Rule 9 (short-term surgical invasive) → Class IIb (administers medicines)
Rule 11 (active therapeutic) → Class IIa default (but IIb for hazardous energy exchange)
Rule 13 (incorporates medicinal substance) → Class III

Result: Class III (Rule 13 produces the highest class)

Documenting the classification rationale

MHRA and UKABs expect the technical file to include a classification rationale that:

States the device's intended purpose precisely
Identifies the relevant device characteristics (invasive/non-invasive, active/non-active, duration, body location)
Lists every rule considered and explains why it does or does not apply
States the final classification with reference to the prevailing rule(s)
References the MHRA guidance or literature consulted

This is not optional — a classification without a documented rationale is not compliant.

Official references

Reference	Description
UK MDR 2002, Schedule 2	Full text of all 18 classification rules
MHRA: Classification of medical devices	MHRA guidance on applying Schedule 2
EU MDD 93/42/EEC, Annex IX	Source of Schedule 2 rules (for reference)

Key definitions used across the rules​

Rules 1–4: Non-invasive devices​

Rule 1 — Default: Class I​

Rule 2 — Channelling or storing blood, body liquids, or tissues​

Rule 3 — Skin, wound, or mucosa contact​

Rule 4 — Devices in contact with injured skin​

Rules 5–8: Invasive devices​

Rule 5 — Body orifice invasive devices (transient)​

Rule 6 — Body orifice invasive devices (short-term)​

Rule 7 — Body orifice invasive devices (long-term)​

Rule 8 — Surgically invasive devices (transient use)​

Rule 9 — Surgically invasive devices (short-term)​

Rule 10 — Active implantable devices​

Rules 9–12: Active devices​

Rule 11 — Active therapeutic devices​

Rule 12 — Active diagnostic devices​

Rules 13–18: Special rules​

Rule 13 — Devices incorporating medicinal substances​

Rule 14 — Devices used for contraception or prevention of STIs​

Rule 15 — Devices specifically for disinfecting, cleaning, rinsing, or hydrating contact lenses​

Rule 16 — Non-active devices specifically intended for recording diagnostic images​

Rule 17 — Devices using animal tissues or cells or their derivatives​

Rule 18 — Blood bags​

Applying multiple rules — the highest-class-prevails principle​

Documenting the classification rationale​

Related pages​

Official references​