MDCG 2018-1: Basic UDI-DI and changes to UDI-DI, explained

Who this applies to

MDCG 2018-1 Rev.4 explains two related decisions: how devices are grouped under a Basic UDI-DI, and when a change requires a new UDI-DI. Manufacturers need both decisions to stay consistent across EUDAMED, certificates, declarations of conformity and technical documentation.

What the Basic UDI-DI is—and is not

The Basic UDI-DI is the main regulatory key connecting devices with the same:

• intended purpose;
• risk class; and
• essential design and manufacturing characteristics.

It identifies the devices in the group uniquely, but it is separate from packaging and labelling and does not appear on any trade item. The UDI-DI identifies a device at a particular packaging level; the Basic UDI-DI connects the regulatory family behind those trade items.

One UDI-DI can belong to one and only one Basic UDI-DI. That rule should be enforced in the product master data, not repaired later during registration.

Where the Basic UDI-DI appears

The Basic UDI-DI connects the device family across regulatory documents. It appears in the EU declaration of conformity and, where applicable, certificates and related technical documentation. Certificates must still clearly identify the covered device names, models or types, intended purpose and classification; the Basic UDI-DI does not replace that scope description.

If several Basic UDI-DIs are associated, document those relationships in the technical dossiers. Keep the family definition and covered-device list aligned whenever the portfolio changes.

When to assign a new UDI-DI

The controlling rule is whether a change could lead to device misidentification or ambiguity in traceability. A new UDI-DI is required in particular for changes to:

• name or trade name;
• device version or model;
• single-use status;
• sterile packaging or the need for sterilisation before use;
• the number of devices in a package;
• critical warnings or contraindications; and
• information concerning CMR substances or endocrine disruptors.

Colour and language changes can also require a new UDI-DI when they can cause misidentification or change safety or performance—for example, safety-relevant colour coding or different local-language variants that cannot be substituted.

Two database details that need judgement

A change in the “directly marked” data element from yes to no forces a new UDI-DI; a change from no to yes does not. A change to the stated type of production identifier does not itself require a new UDI-DI as long as the label does not change.

For reusable devices, “maximum number of reuses” is applicable only when clinical evidence and risk management establish a limit. If the manufacturer claims such a maximum, it belongs in the UDI database and instructions for use. Changing that established maximum requires a new UDI-DI.

What this means for you, practically

For each product or master-data change, capture:

1. the current Basic UDI-DI and UDI-DI;
2. the affected device, package and database attributes;
3. whether intended purpose, risk class or essential characteristics change;
4. whether users or supply-chain partners could misidentify the device;
5. the new-identifier decision and rationale; and
6. the documents, labels, certificates and registrations that need updating.

Software has additional version rules in MDCG 2018-5. MDCG 2021-19 explains how to embed these decisions in the quality management system.

Read the official MDCG 2018-1 Rev.4 guidance.