What is an IVD?
This page is based on Regulation 2(1) and Part III of the UK Medical Devices Regulations 2002 (SI 2002/618, as amended). Part III implements the former EU IVDD 98/79/EC in retained UK law. IVD medical devices are subject to separate classification and conformity assessment rules from general medical devices.
This site provides general information only and does not constitute legal or regulatory advice. Always consult the official legislation text and, where appropriate, a qualified regulatory professional.
The legal definition
Under Regulation 2(1) Part III of the UK MDR 2002, an in vitro diagnostic medical device (IVD) is defined as any medical device that is a:
reagent, reagent product, calibrator, control material, kit, instrument, apparatus, equipment or system — whether used alone or in combination — intended by its manufacturer to be used in vitro for the examination of specimens derived from the human body, including blood and tissue donations.
The examination must be intended solely or principally for the purpose of providing information concerning:
| Purpose | Examples |
|---|---|
| A physiological or pathological state | Glucose tests, CRP assays, troponin testing |
| A congenital abnormality | NIPT (non-invasive prenatal testing), chromosomal analysis |
| Safety and compatibility with potential recipients | Blood grouping, HLA typing, cross-matching |
| Monitoring therapeutic measures | Drug level monitoring (e.g., vancomycin, cyclosporine) |
Specimen collection containers — even though not analytical themselves — are also regulated as IVDs under Part III if intended for the collection and preservation of specimens for IVD examination.
Why IVDs are regulated separately
IVDs do not physically interact with the patient's body in the same way as general medical devices. However, they carry significant indirect risk: an incorrect diagnostic result can lead to:
- Under-treatment of a serious condition (false negative)
- Over-treatment with harmful therapies (false positive)
- Transfusion reactions from incorrect blood group assignment
- Transmission of blood-borne infections via incorrectly cleared donations
Because the risk is informational rather than physical, IVDs are assessed differently — the key metrics are analytical performance (accuracy, precision, specificity, sensitivity) and clinical performance (what the test result means for patient management).
UK IVD classification
Unlike general medical devices — which use Classes I, IIa, IIb, and III — IVDs under UK MDR 2002 Part III use a different four-category system based on the Annex II lists and the concept of self-testing:
| Category | Risk level | Basis | Examples |
|---|---|---|---|
| Annex II List A | Highest risk | Listed in Annex II, List A of UK MDR 2002 Part III | HIV 1 & 2 detection, HTLV I & II, Hepatitis B/C, ABO blood grouping, Rh blood grouping |
| Annex II List B | Significant risk | Listed in Annex II, List B of UK MDR 2002 Part III | Rubella, toxoplasma, PKU screening, PSA testing, blood glucose (professional use) |
| Self-test devices | Variable | Intended for use by lay persons without professional training | Home pregnancy tests, consumer blood glucose meters, home HIV tests |
| General IVDs | Lowest (regulated) risk | All other IVDs not in Lists A, B, or Self-test | Most routine clinical chemistry, haematology analysers, specimen tubes |
Annex II List A — the highest-risk IVDs
List A IVDs carry the greatest potential public health impact, typically because:
- They detect life-threatening communicable diseases
- They determine compatibility for blood transfusions or transplantation
- Errors can have irreversible consequences for patients or blood supply safety
Current List A devices include:
- Reagents and reagent products for the detection of HIV 1 and HIV 2
- Reagents and reagent products for HTLV I and HTLV II
- Reagents and reagent products for Hepatitis B, Hepatitis C, and Hepatitis D
- ABO blood grouping systems, Rh blood grouping (anti-D, anti-C, anti-c, anti-E, anti-e), Kell, Kidd, Duffy systems
- Anti-Kell reagents
- Reagents for detection of irregular anti-erythrocyte antibodies
List A devices require conformity assessment by a UK Approved Body (UKAB) with examination of design dossier and production quality assurance.
Annex II List B — significant-risk IVDs
List B IVDs relate to conditions or uses where diagnostic errors carry significant (though generally less catastrophic) risk.
Current List B devices include:
- Reagents for rubella, toxoplasma, cytomegalovirus (CMV)
- Reagents for phenylketonuria (PKU) — neonatal screening
- Reagents for congenital hypothyroidism screening
- Human chorionic gonadotropin (hCG) — pregnancy testing (professional use)
- Prostate specific antigen (PSA)
- Blood glucose testing reagents for professional use
- Legal self-testing blood glucose meters that also have a professional label
- Haemoglobin determinations
List B devices require UKAB involvement, but through a less intensive assessment route than List A.
Self-test devices
Any IVD — regardless of whether it would otherwise be List A, List B, or General — that is specifically designed and intended for use by lay persons in a home setting is a self-test device and subject to specific labelling, instructions, and performance requirements.
Examples: Home pregnancy tests, consumer blood glucose meters, home HIV tests, lateral flow tests purchased by members of the public, home cholesterol tests.
The COVID-19 lateral flow tests made available to the UK public during the pandemic are self-test IVDs. Their regulatory handling under emergency provisions highlighted both the flexibility and the complexity of the self-test category.
Key difference from EU IVDR
A critical point for manufacturers with both GB and EU market access:
| Framework | Classification system |
|---|---|
| UK MDR 2002 (GB market) | List A / List B / Self-test / General (based on former IVDD 98/79/EC) |
| EU IVDR 2017/746 (EU & NI market) | Class A / B / C / D (new risk-based classification, Annex VIII Rules 1–7) |
These systems are not equivalent. Many IVDs that were previously "General" under the IVDD (and remain General under UK Part III) have been upclassified to Class B or Class C under the EU IVDR. Manufacturers operating in both markets must satisfy both classification determinations independently.
For Northern Ireland specifically, EU IVDR 2017/746 applies — not UK MDR 2002 Part III. See Great Britain vs Northern Ireland.
Performance evaluation for IVDs
General medical devices require clinical evaluation. IVDs require an equivalent process called performance evaluation, which covers:
- Analytical performance — sensitivity, specificity, accuracy, precision, limits of detection, measuring range, linearity, cut-off determination
- Clinical performance — diagnostic sensitivity, diagnostic specificity, positive predictive value, negative predictive value in the intended population
- Scientific validity — the relationship between the analyte and the clinical state being diagnosed
Performance evaluation must be documented in a performance evaluation report, supported by a performance evaluation plan, and kept updated as part of the post-market performance follow-up (PMPF).
Instruments and laboratory equipment
General-purpose laboratory instruments (centrifuges, pipettes, incubators, spectrophotometers) are not IVDs unless they are specifically intended by their manufacturer to be used for in vitro examination of human-derived specimens for medical purposes.
The same instrument sold with:
- A general-purpose label → not an IVD
- A label claiming it is intended for clinical diagnostic use → potentially an IVD
Intended purpose and labelling again determine regulatory status.
Related pages
- What is a medical device? — general medical device definition
- What is not a medical device? — exclusions and borderlines
- Great Britain vs Northern Ireland — EU IVDR applies in NI; UK MDR Part III applies in GB
- IVD classification — List A · List B · Self-test · General
- Performance evaluation for IVDs
Official references
| Reference | Description |
|---|---|
| UK MDR 2002, Reg 2(1) Part III | Definition of IVD medical device |
| UK MDR 2002, Part III, Annex II | Lists A and B of higher-risk IVDs |
| UK MDR 2002, Part III, Annex III | Self-test device provisions |
| SI 2019/791 | Post-Brexit amendments to IVD provisions |
| MHRA guidance: IVD medical devices | MHRA's regulatory guidance for IVD manufacturers |
| EU IVDR 2017/746 | Applies in Northern Ireland under the Windsor Framework |