The UDI system serves to uniquely identify and trace medical devices and in vitro diagnostic devices. The UDI consists of the UDI-DI as the identifier for the manufacturer and product, and the UDI-PI for the specific production unit. In addition, the Basic UDI-DI links a group of products with the same intended purpose, risk class, and key design and manufacturing characteristics within the European documentation and database systems.
UDI-DI and UDI-PI
The UDI-DI is product-specific and provides access to the stored product information. The UDI-PI identifies the production unit and may include details such as batch, serial number, date of manufacture, expiry date, or a software identifier. Together, the two parts make it possible to distinguish a specific product model from the unit actually supplied.
The manufacturer assigns the UDI to the device and to higher levels of packaging before placing it on the market. The UDI carrier is affixed to the label or packaging; for reusable devices, direct marking on the device may be provided. The system supplements existing labeling requirements rather than replacing them.
Function of the Basic UDI-DI
The Basic UDI-DI sits above the individual UDI-DIs. It is the central key for the UDI database and for relevant documents such as certificates, the EU Declaration of Conformity, technical documentation, and summaries of safety and performance. A group under a Basic UDI-DI must share the same intended purpose, risk class, and key design and manufacturing characteristics.
The Basic UDI-DI does not appear on a trade item and is separate from packaging and labelling. A single Basic UDI-DI can be linked to one or more UDI-DIs, while each UDI-DI is assigned to only one Basic UDI-DI. This structure links variants of a product family to overarching regulatory evidence without sacrificing traceability of individual units.
The UDI database captures the information that describes the product before it is placed on the market. Manufacturers must therefore keep the mapping between product model, Basic UDI-DI, UDI-DI, and the technical documentation stable within change control. If a characteristic changes such that identification or traceability is no longer unambiguous, a new UDI-DI may be required.
For economic operators and healthcare institutions, machine-readable marking enables structured capture at goods receipt, during use, and in field safety corrective actions. Its practical effectiveness depends on the marking applied to the packaging or product matching the information maintained in databases and in the quality management system. Incorrect master data can hinder traceability even if the code is printed correctly.
Assigning identifiers is therefore not merely a label-design task. It affects product development, Regulatory Affairs, quality management, packaging, and data maintenance in EUDAMED. When a product variant is created or changed, it must be assessed whether it can still be assigned to the existing product group and whether the documentation makes this decision clearly traceable.
For the Basic UDI-DI, consistency of the product-grouping logic is central. If devices with different intended purposes or risk classes are grouped under it, the key loses its function as a reliable link between the certificate, the Declaration of Conformity, and the technical dossier. Conversely, overly granular grouping can unnecessarily complicate maintenance of the associated UDI-DIs.
Distinguishing between database key and product marking
The Basic UDI-DI is not the marking that users see on the product. It is the database key for the European product group and is referenced in regulatory documents. The label or packaging, by contrast, carries the UDI carrier, which represents the UDI-DI and UDI-PI for the specific product and its production.
This distinction is essential for registrations and recalls. The Basic UDI-DI can be used to locate the related product information and documents; the UDI-DI and UDI-PI can be used to determine which model and which production batch or serial number are affected. The three identifiers therefore fulfil different, but linked, tasks.
Relevance for clinical trials
In clinical investigations, consistent identification facilitates linking the investigational product, product version, batch, and participant data. Especially for software-based devices, variants within a product family, or returns of defective units, it must be clear which configuration was used. Study logistics should therefore link UDI data with goods receipt, dispensing, return, and product deficiency reports, without compromising blinding or data protection.
Full-service CROs such as Mediconomics support the definition of product identifiers in the protocol, logistics documentation, and databases, as well as alignment with the manufacturer’s technical documentation data. They establish processes for device accountability, reconciliation, and traceability so that a safety query during the study can be tied specifically to model, batch, or serial number.
Frequently Asked Questions (FAQ)
Which information distinguishes individual production batches?
The UDI-PI identifies the production unit and may include, among other things, the batch, serial number, date of manufacture, or expiry date.
Is the Basic UDI-DI shown on the product label?
No. It is separate from the label and packaging and serves as a higher-level key in the database and regulatory documentation.
When is a new UDI-DI required?
The MDCG cites changes that can lead to misidentification or unclear traceability as a reason to assign a new UDI-DI.
Regulatory References
- Regulation (EU) 2017/745, Article 27 and Annex VI – establishes the UDI system for medical devices.
- Regulation (EU) 2017/746, Article 24 and Annex VI – contains the UDI requirements for IVDs.
- MDCG 2018-1 Rev.4 – explains the Basic UDI-DI and changes to the UDI-DI.
- European Commission, Unique Device Identifier – describes the system’s components, database, and marking.