Page Last Reviewed: 21 January 2026

Formal Definition

The formal definition of an accessory for a medical devices is:

MDR, Article 2(2): ‘accessory for a medical device’ means an article which, whilst not being itself a medical device, is intended by its manufacturer to be used together with one or several particular medical device(s) to specifically enable the medical device(s) to be used in accordance with its/their intended purpose(s) or to specifically and directly assist the medical functionality of the medical device(s) in terms of its/their intended purpose(s);

IVDR, Article 2(4): ‘accessory for an in vitro diagnostic medical device’ means an article which, whilst not being itself an in vitro diagnostic medical device, is intended by its manufacturer to be used together with one or several particular in vitro diagnostic medical device(s) to specifically enable the in vitro diagnostic medical device(s) to be used in accordance with its/their intended purpose(s) or to specifically and directly assist the medical functionality of the in vitro diagnostic medical device(s) in terms of its/their intended purpose(s);

For the purpose of this article, “accessory for a medical device” will take the meaning of both an accessory to a medical device under the MDR and an accessory to an in vitro diagnostic medical device under the IVDR.

‘Medical Device’ vs ‘Accessory to a Medical Device‘

Medical device accessories are differentiated from a medical device based on three primary criteria.

1) It must not have an independent medical purpose of its own.

If a product has an independent medical purpose, it must be considered as a medical device on its own, and not as an accessory to a medical device.

Determining whether a product is an accessory depends on its intended use statement, mode of action, and performances claimed.

Examples

If a smartphone application is intended to display the outcomes of a blood pressure monitor, it would meet the definition of accessory for a medical device. However, if the application processes and analyzes the results, or provides medical recommendations, then it meets the definition of medical device. Or, if it does not claim to display medical data such as blood pressure, and it purely displays data in general, it would not be an accessory to the medical device or a medical device.

Surgical implant drills might be considered mere tools for the implant itself. However, because they are specifically designed to prepare the bone for implantation, they fulfill the criteria of a medical device, i.e., inherently, they are medical devices and not accessories to a medical device.

2) It must be used with a specific medical device (or devices).

Accessories need to be used with one (or several) specified medical devices. Further, safety and performance must be demonstrated for use of the accessories with the specified device(s).

Medical device accessories must be designed, manufactured, packaged, etc., in a controlled quality management system environment, to confirm their suitability with a particular medical device. This means manufacturers cannot designate generic, off-the-shelf “products” as accessories to their medical devices. They must perform all verification and validation activities to ensure the accessory is compatible.

3) It must specifically enable the medical device to achieve its intended purpose, functionality and/or performance.

The primary objective of a medical device accessory is to ensure a medical device performs as intended or achieves the functionality and/or performance claimed.

When considering if a product is an accessory or not, assess if it “specifically enable[s]” the medical device to be used to its intended purpose. Or if it “specifically and directly assist[s] the medical functionality” of the medical device. If it does not, then it may not be an accessory as defined under the Regulation. The manufacturer should document its rationale either way.

If the manufacturer determines the product is not an accessory to a medical device, other considerations may apply for the products to be sold together. For example, the requirements under MDR Article 22 ‘Systems and Procedure Packs‘.

“Optional” Accessories

The term ‘accessory’ is often incorrectly used in respect to the MDR/IVDR. As outlined above, the accessory must specifically enable the medical device to achieve its intended purpose, functionality, and/or performance.

Sometimes manufacturers have products that they describe to customers as an “optional accessory”, which can be used in combination with the principal medical device. However, it is important to remember that if the “optional” accessory is not intended to support the medical device’s claimed performance or functionality, or to ensure its use as intended, then it may not be a medical device accessory as defined by the Regulation. Instead, it may be:

• A separate medical device (not an accessory to a medical device) under EU MDR, if it has a medical purpose. For instance, a stethoscope that is used to monitor the patient’s condition while using an infusion pump.
• A general product that does not fall under the scope of EU MDR, if it does not have a medical purpose. In that case, other legislation may apply, such as the General Product Safety Directive 2001/95/EC. For instance, a decorative cover for a wheelchair or a cushion that is used to make a hospital bed more comfortable for the patient.

Examples of Medical Device Accessories

CE Marking Medical Device Accessories

Per MDR* Article 1(4), medical devices, accessories for medical devices, and devices without medical purposes (Annex XVI) are all categorized together under the term “devices.”

This terminology is used consistently across all MDR requirements, except when specific requirements are applicable to only a particular category of these products. As a result, accessories for medical devices are subject to the same regulatory framework as medical devices. This includes the necessity for classification and determining the appropriate regulatory pathway, and, if required, involvement of a Notified Body.  

Additionally, manufacturers must generate evidence of compliance with the General Safety and Performance Requirements (GSPR) specific to accessories. This evidence must support the safety and performance of the accessory throughout its lifecycle. It should cover aspects such as design, manufacturing, testing, clinical evidence, post-market surveillance, etc.

*IVDR Article 1(2).

Classification

MDR, Annex VIII(3.2): “If the device in question is intended to be used in combination with another device, the classification rules shall apply separately to each of the devices. Accessories for a medical device shall be classified in their own right separately from the device with which they are used.”

Despite common misconception, accessories are not always the same classification as the parent device. Although, it is generally expected that medical device accessories should not be classified higher than the parent device.

Accessories for medical devices are classified based on the same principles as medical devices, i.e., taking into account the product itself and its intended use.

Classification of medical device accessories is determined using criteria outlined in MDR* Annex VIII. Various factors must be assessed, such as the:

They are classified according to risk-based rules and sub-rules, each associated with a specific classification. When an accessory meets the criteria of multiple rules or sub-rules, it is assigned the highest classification applicable.

Examples (and exception to the rule)

In these examples, both the medical devices and their corresponding accessories do not share the same characteristics. This typically results in different classifications for the devices. However, note that while ‘Example 1’ will fall under a different classification rule, there is an exception for active implantable device accessories. These are governed under Rule 8, indent 6 along with the main device, and are automatically classified as Class III, i.e., ‘Example 2’ will be Class III irrespective of its differing characteristics.

*IVDR Annex VIII considerations and risk classifications are different in nature.

Technical Documentation File (TDF)

Manufacturers often ask whether they should develop specific documentation for accessories, or if they can integrate all data into the same Technical Documentation File (TDF).

This decision is not straightforward and requires careful consideration on a case-by-case basis.

Certain documents will overlap between the accessory and the parent device. For example, the ISO 13485 standard (sections 7.3.6 and 7.3.7) requires design verification and validation (V&V) activities when the device is used in conjunction with other devices, i.e., with interface or connection. These design control activities, and their corresponding V&V reports, support the safety and performance of both the accessory and the parent device.

From a regulatory standpoint, whether devices can be combined in the same TDF also depends on factors like product classifications and intended use. Although manufacturers may prefer to bundle medical devices and accessories together, they must consider Notified Body sampling principles for TDF assessment, as outlined in MDCG 2019-13 (Revision 1; December 2024).

Bundling Basic UDI-DIs for the parent and accessory devices may be justified under certain conditions. For example, if they share the same EMDN code (for Class IIb devices) or MDN/MDA code (for Class IIa devices), or have the same verification and validation activities. However, the rationale can still be challenged, and the response may vary between Notified Bodies due to their internal policies. Therefore, it is generally advisable to issue a separate TDF for each Basic UDI-DI.

Class III devices (both parent devices and accessories) typically require a separate TDF for each Basic UDI-DI.

Regardless of the device classification, it is recommended to issue a separate Declaration of Conformity for each Basic UDI-DI to simplify the Notified Body sampling method, which is based on the number of Basic UDI-DIs.

Labeling

When it comes to labeling, the same General Safety and Performance Requirements (GSPRs) apply to both medical devices and their accessories. However, this does not mean that these products will feature the same level of information or identical symbols. For example, a medical device might be designed for single use, while its accessory could be reusable. Consequently, the labeling, including labels and instructions for use (IFU), will differ based on the characteristics of each product.

It’s also important to note that the MDR does not mandate a specific IFU for an accessory. Manufacturers have the flexibility to create either one comprehensive IFU or separate IFUs for the device and its accessory to ensure safe usage. If a single IFU is used, it must meet the applicable GSPR requirements for both the principle device and the accessory.

‘Medical Device’ Symbol (or text) on Label

MDR Annex I 23.2(q)* requires the label to include “an indication that the device is a medical device”.  This is often achieved through use of the ‘medical device’ symbol in European Harmonized Standard EN ISO 15223-1:2021 (‘MD’).

In the MDR, medical devices, accessories to medical devices, and Annex XVI devices are all together named “devices”. However, the ‘MD’ symbol is required for “medical devices”. While that can be interpreted to mean only the medical device (not the accessory) should bear the symbol, the Regulation is not explicitly clear. Particularly because accessories, while not “medical devices”, do fall under purview of the MDR and have a medical purpose.

Considering there may be differences of opinion between regulatory reviewers, manufacturers should document the justification and rationale for either scenario, i.e., identifying the accessory with the ‘MD’ symbol or not. Where a manufacturer’s device undergoes conformity assessment by a Notified Body, the final decision would likely be determined by the Notified Body’s position.  

*IVDR Annex I 20.2(e) requires the label to include “an indication that the device is an in vitro diagnostic medical device”. This is often achieved through use of the ‘in vitro diagnostic medical device’ symbol in EN ISO 15223-1:2021 (‘IVD’).

Basic UDI-DI

As a medical device and accessory to the medical device do not have the same design and manufacturing processes, they each need their own Basic UDI-DI.

Clinical Evaluation Report

An accessory generally shares the same clinical data as the parent device; therefore, bundling them together in the same evaluation is practical and relevant. However, if an accessory is intended for use with multiple parent devices, then an independent clinical evaluation is recommended. Particularly for Class III accessories, since the Basic UDI-DI of an accessory cannot be in scope of multiple Summary of Safety and Clinical Performances (SSCPs).

Risk Assessment

While specific requirements are not outlined in the MDR/IVDR or ISO 14971, it is advisable to conduct a distinct risk assessment for each product due to differences in product lifecycle, risk evaluation criteria, potential harms, and hazardous situations.

Post-market Surveillance (PMS) Report

MDCG 2022-21 (Revision 0; December 2022) allows for the bundling of devices with differing classifications in the same PMS report, if there is a sound rationale for doing so.

An accessory is designed to be used with a medical device. As such, it is reasonable to argue that the accessory’s use impacts the performance and risks associated with the medical device during the post-market phase. Therefore, including both a medical device and its accessory in the same PMS Report or Periodic Safety Update Report (PSUR) is typically considered appropriate in most cases. That said, the justification always needs to be approved by the Notified Body, where applicable.

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Parts and Components vs Accessories

Accessories for medical devices are manufactured separately from the assembled and finished device it supports, bear CE Marking, and are individually classified (separate from the parent medical device) – except for active implantable device accessories, which are always Class III per MDR Rule 8.

While the MDR/IVDR does contain a section on ‘Parts and Components’ (Articles 23 & 20 respectively), it does not define a component or a part. That said, they are generally an integral part of the assembled and finished medical device. And, without which, the finished device would not be able to function to its intended purpose. Unlike accessories, components/parts do not bear individual CE Marking. Instead, they are part of the finished device’s CE Marking. The terms parts and components are generally used synonymously.

A medical device’s part/component may become worn or defective and need to be replaced. Replacements may be made as long as it does not adversely affect, or significantly change, the safety and performance of the device. In this case, the replacement part/component being shipped would not bear individual CE Marking.