Medical Device Classification Under MDR Annex VIII: The 22 Rules
Updated: Aug 30
Medical device classification is the first decision in an MDR file and the one that determines every cost after it. Article 51(1) divides devices into classes I, IIa, IIb and III, taking into account the intended purpose and the inherent risks, and requires classification to be carried out in accordance with Annex VIII. Get it wrong and the conformity assessment route, the notified body scope, the technical documentation sampling and the transitional deadline are all wrong with it.
Where medical device classification starts: Article 51 and the intended purpose
Annex VIII is organised in three chapters. Chapter I holds the definitions specific to the classification rules. Chapter II holds Section 3, the implementing rules. Chapter III holds the rules themselves, grouped into Section 4 for non-invasive devices, Section 5 for invasive devices, Section 6 for active devices and Section 7 for the special rules. The numbering is continuous across the chapters, which is why Commission acts derogating from a rule cite a section number rather than a rule number — Implementing Regulation (EU) 2022/2347 derogates from Section 6.5 of Annex VIII, which is Rule 13.
Implementing rule 3.1 governs everything else: application of the classification rules shall be governed by the intended purpose of the devices. MDCG 2021-24 Rev.1 states the consequence bluntly — it is the intended and not the accidental use of the device that determines the class. Two products of identical construction classify differently on the strength of what the manufacturer states they are for. The guidance also clarifies that duration is the duration of effect, not the duration of application: a preparation applied in seconds but active for hours is counted by its effect.
Article 51(2) matters more to a non-EU manufacturer than it looks. A dispute between the manufacturer and the notified body arising from the application of Annex VIII is referred to the competent authority of the Member State in which the manufacturer has its registered place of business. Where the manufacturer has no registered place of business in the Union, the matter goes to the competent authority of the Member State in which the authorised representative referred to in the last indent of point (b) of the second paragraph of Section 2.2 of Annex IX has its registered place of business. Your choice of representative jurisdiction decides which national authority adjudicates your classification.
The definitions that decide more than the rules do
Section 1 of Chapter I sets three durations and they are exact. Transient means normally intended for continuous use for less than 60 minutes. Short term means normally intended for continuous use for between 60 minutes and 30 days. Long term means normally intended for continuous use for more than 30 days. Implementing rule 3.6 then defines continuous use as the entire duration of use of the same device without regard to temporary interruption for cleaning or disinfection, and as the accumulated use of a device intended to be replaced immediately with another of the same type.
Section 2 runs from 2.1 to 2.8. Body orifice means any natural opening in the body, as well as the external surface of the eyeball, or any permanent artificial opening such as a stoma. Central circulatory system is a closed list of fourteen named vessels, from the arteriae pulmonales through the aorta to the bifurcatio aortae, the coronary and carotid arteries, the cerebral arteries, the truncus brachiocephalicus, the cardiac and pulmonary veins and both venae cavae. Central nervous system means the brain, meninges and spinal cord. Injured skin or mucous membrane means an area presenting a pathological change or change following disease or a wound.
Here is a detail that catches careful readers. Section 2 is headed “invasive and active devices”, but it does not define either term. “Invasive device” and “active device” are defined in Article 2, points (6) and (4), not in Annex VIII. What Section 2 defines is surgically invasive device, reusable surgical instrument, active therapeutic device and active device intended for diagnosis and monitoring. A medical device classification rationale that cites Annex VIII for the definition of an active device is citing the wrong instrument.
The seven implementing rules, and the one that decides borderline files
Section 3 has seven sub-rules, not six. 3.1 makes intended purpose governing. 3.2 applies the rules separately to each device where devices are used in combination, and classifies accessories in their own right. 3.3 puts software that drives or influences the use of a device in the same class as that device, and classifies independent software in its own right. 3.4 requires a device not intended for a specific part of the body to be classified on the basis of the most critical specified use. 3.6 defines continuous use. 3.7 — the one almost nobody cites — provides that a device is considered to allow direct diagnosis when it provides the diagnosis by itself or when it provides decisive information for the diagnosis.
3.5 is the rule that decides borderline files: if several rules, or if, within the same rule, several sub-rules, apply to the same device based on the device’s intended purpose, the strictest rule and sub-rule resulting in the higher classification shall apply. MDCG 2021-24 Rev.1 extends this to the device as a whole — the characteristic matching the intended purpose that falls into the highest class determines the class of the entire device. Adding one secondary claim to an intended purpose statement can move a whole product line up a class.
One textual point is worth knowing if you are working from an old copy. Section 3.2 as published in the Official Journal on 5 May 2017 read “accessories for a medical device and for a product listed in Annex XVI shall be classified in their own right”. The words “and for a product listed in Annex XVI” were deleted by the corrigendum published in OJ L 117 of 3 May 2019. That corrigendum is the only correction that touches Annex VIII at all; the corrigendum of 27 December 2019 does not.
Rules 1 to 13: non-invasive, invasive and active devices
The three main sections do most of the medical device classification work, and they read in order. Section 4 covers non-invasive devices. Rule 1 puts devices that do not touch the patient, or touch intact skin only, in class I. Rule 2 covers channelling or storing, with class IIa where the device connects to a class IIa, IIb or III active device or channels blood, body liquids, cells or tissues, and class IIb for blood bags. Rule 3 covers modification of the biological or chemical composition of blood or body liquids — class IIb as a rule, class IIa where the treatment is filtration, centrifugation or exchange of gas or heat. Rule 4 covers contact with injured skin or mucous membrane, from class I for a mechanical barrier up to class IIb for wounds which have breached the dermis and heal by secondary intent.
Section 5 covers invasive devices and turns on duration and site. Rule 5 handles body orifices other than surgically: transient is class I, short term class IIa, long term class IIb, with a reduction for the oral cavity as far as the pharynx, the ear canal up to the ear drum and the nasal cavity where the device is not liable to be absorbed by the mucous membrane, and class IIa for devices connected to a class IIa or higher active device. Rules 6 and 7 handle transient and short-term surgically invasive devices at class IIa, with class III where the device is used in direct contact with the heart, the central circulatory system or the central nervous system, and class IIb for ionising radiation, biological effect or absorption, and medicinal product administration.
Rule 8 covers implantable and long-term surgically invasive devices at class IIb, dropping to class IIa for devices intended to be placed in the teeth, and rising to class III for direct contact with the heart, the central circulatory system or the central nervous system, for biological effect or absorption, for chemical change in the body, for medicinal product administration, for active implantable devices and their accessories, for breast implants and surgical meshes, and for total or partial joint replacements and spinal disc replacement implants — with an exception in each case for ancillary components such as screws, wedges, plates and instruments. Section 6 then covers active devices: Rule 9 for therapeutic energy, Rule 10 for diagnosis and monitoring, Rule 12 for administering or removing medicinal products at class IIa with a class IIb uplift where done in a potentially hazardous manner, and Rule 13 as the residual — all other active devices are class I.
Rule 11 is the one that reshaped an entire product category. Software intended to provide information which is used to take decisions with diagnosis or therapeutic purposes is class IIa, except where such decisions have an impact that may cause death or an irreversible deterioration of a person’s state of health, in which case it is in class III, or a serious deterioration of a person’s state of health or a surgical intervention, in which case it is class IIb. Software intended to monitor physiological processes is class IIa, except where intended for monitoring of vital physiological parameters where the nature of variations is such that it could result in immediate danger to the patient, in which case it is class IIb. All other software is class I. MDCG 2019-11 Rev.1 of June 2025 gives the qualification and classification decision steps.
Rules 14 to 22: the special rules that catch whole categories
Section 7 is where product categories are captured wholesale, and the outcomes are frequently misquoted. Rule 14 puts devices incorporating, as an integral part, a substance which if used separately can be considered a medicinal product — including a medicinal product derived from human blood or plasma — and that has an action ancillary to that of the device, in class III. Rule 15 puts contraception and prevention of sexually transmitted disease in class IIb, rising to class III where the device is implantable or long-term invasive. Rule 17 puts devices specifically intended for recording of diagnostic images generated by X-ray radiation in class IIa.
Rule 16 has two limbs and one qualifier that is often dropped. Devices specifically intended for disinfecting, cleaning, rinsing or hydrating contact lenses are class IIb. Devices specifically intended for disinfecting or sterilising medical devices are class IIa, unless they are disinfecting solutions or washer-disinfectors intended specifically for disinfecting invasive devices as the end point of processing, in which case they are class IIb. The rule does not apply to devices that clean devices other than contact lenses by physical action only. Rule 18 puts devices manufactured utilising human or animal tissues or cells, or their derivatives, which are non-viable or rendered non-viable, in class III — with an exception only for animal-origin material in devices intended to come into contact with intact skin only.
Rule 19 splits nanomaterial three ways: class III for a high or medium potential for internal exposure, class IIb for a low potential, class IIa for a negligible potential. Note that high and medium sit in the same indent. Rule 20 puts inhalation administration of medicinal products through body orifices at class IIa, rising to class IIb where the mode of action has an essential impact on the efficacy and safety of the administered medicinal product or the device is intended to treat life-threatening conditions. Rule 21 covers substance-based devices in four indents: class III where they or their metabolites are systemically absorbed in order to achieve the intended purpose; class III where they achieve their purpose in the stomach or lower gastrointestinal tract and are systemically absorbed; class IIa where applied to the skin or in the nasal or oral cavity as far as the pharynx and achieving their purpose on those cavities; class IIb in all other cases. Rule 22 puts active therapeutic devices with an integrated diagnostic function which significantly determines patient management — the rule names closed loop systems and automated external defibrillators — in class III.
Class I is not one class: Is, Im and Ir
Article 52(7) lets manufacturers of class I devices declare conformity by issuing the EU declaration of conformity after drawing up the technical documentation in Annexes II and III. The sentence that follows is the one that surprises people. If those devices are placed on the market in sterile condition, have a measuring function, or are reusable surgical instruments, the manufacturer must apply the procedures in Chapters I and III of Annex IX, or in Part A of Annex XI. A notified body is involved.
The involvement is scoped, and the scoping language is precise. For sterile devices it is limited to the aspects relating to establishing, securing and maintaining sterile conditions. For devices with a measuring function it is limited to the aspects relating to conformity with the metrological requirements. For reusable surgical instruments it is limited to the aspects relating to the reuse of the device, in particular cleaning, disinfection, sterilization, maintenance and functional testing and the related instructions for use.
MDCG 2021-24 Rev.1 gives a three-part test for a measuring function: the device performs a quantitative measurement of a physiological or anatomical parameter, or of a quantity of energy or substance; the result is displayed in legal units or compared to a reference point expressed in such units; and the intended purpose implies an accuracy such that non-compliance could significantly affect patient safety. Medical device classification does not end at the class letter. A device that displays a number is not automatically class Im, and a device that does meet all three is not class I plain, whatever the file says. MDCG 2019-15 rev.1 of July 2020 is the working guide for these manufacturers.
What your medical device classification decides downstream
Article 52 sets the conformity assessment route by class, and the notified body’s involvement grows with the class. Technical documentation is sampled: for class IIa at least one representative device for each category of devices, for class IIb at least one representative device per generic device group. For class IIb implantable devices the assessment applies to every device, subject to an exemption list — and that list changed this summer. Commission Delegated Regulation (EU) 2026/1359 of 20 March 2026, published in the Official Journal on 29 June 2026, replaced the second subparagraph of Article 52(4) with a two-limb list. Limb (a) reproduces the original twelve items. Limb (b) adds a long list of well-established technologies including cannulas, catheters, feeding tubes, bone wax, bone fillers, bone substitutes, dental implants, orthodontic devices, spinal posterior fixations and suspensory fixations. Any classification article written before July 2026 has the old list.
Classification also decides the post-market cadence — a periodic safety update report at least every two years for class IIa and at least annually for class IIb and class III, against a post-market surveillance report under Article 85 for class I — and it decides which Article 120 transitional date applied to a legacy device. It decides whether the clinical evaluation consultation procedure under Article 54 is triggered. None of this is recoverable later: a device registered in EUDAMED under the wrong risk class carries that medical device classification error into every downstream record.
Two provisions keep this with the manufacturer. Article 11(4) states that the mandate given to an authorised representative shall not delegate the obligations in Article 10(1), (2), (3), (4), (6), (7), (9), (10), (11) and (12) — classification and technical documentation sit inside that list. Article 11(3)(c) then requires the representative to comply with the Article 31 registration obligations and verify that the manufacturer has complied with Articles 27 and 29, and Article 29 registration carries the risk class. A misclassification is one of the few things a representative is legally obliged to catch rather than merely hold. We are not a law firm and do not provide legal advice.
Sources
Regulation (EU) 2017/745, Articles 2(4), 2(6), 11(3), 11(4), 51, 52(4) and 52(7); Annex VIII Chapters I, II and III (Sections 1 to 7, Rules 1 to 22); Annex IX Section 2.2
Corrigendum to Regulation (EU) 2017/745, OJ L 117, 3 May 2019 (Annex VIII, Chapter II, Section 3.2)
Commission Delegated Regulation (EU) 2026/1359 of 20 March 2026 amending Regulation (EU) 2017/745 as regards the list of class IIb implantable devices exempted from the obligation to perform an assessment of the technical documentation for every device, OJ L, 2026/1359, 29 June 2026
MDCG 2021-24 Rev.1 — Guidance on classification of medical devices, April 2026
MDCG 2019-11 Rev.1 — Guidance on Qualification and Classification of Software in Regulation (EU) 2017/745 and Regulation (EU) 2017/746, June 2025
MDCG 2019-15 rev.1 — Guidance Notes for Manufacturers of Class I Medical Devices, July 2020; Commission Implementing Regulation (EU) 2022/2347 of 1 December 2022, OJ L 311, 2 December 2022
Who wrote this
Medex is a medical device manufacturer established in Ankara and a registered authorised representative in EUDAMED under SRN TR-AR-000057550. We are not a law firm and do not provide legal advice. Send us your device list with the stated intended purpose of each device, and we will respond in writing.
Medex acts as EU authorised representative for manufacturers outside the Union and files their EUDAMED registrations, where the risk class assigned under Annex VIII is recorded against the device and is visible to competent authorities.
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