UDIs explained

by | Mar 16, 2022 | Clinical Writing, IVD, MDR

MHRA Guidance

Lifting the veil on UDIs, BUDIs and the rest…….

Here at IMed, to stay up to date with the industries’ concerns about medical devices and medical device regulations, we keep a keen eye on a number of online forums that are a haven of regulatory queries, questions, and discussions.

One of the most frequently asked about topics is UDI codes. There appears to be a lot of confusion as to what the function of UDIs and associated codes actually are. In a recent IMed poll, only 56% of answers correctly identified the purpose of the UDI-PI code, which is a lower level of correct answers than in some of our previous polls..


So, I wanted to provide IMed’s Network of followers with this short blog, introducing & explaining about the real use and purpose of UDIs.
The Unique Device Identifier (UDI) of a device is a code that functions to make a device globally and unambigously identifiable, scanable, and so that information associated to a device can be retrieved from a regulatory database.

It is defined both within the MDR and the IVDR as:


‘a series of numeric or alphanumeric characters that is created through internationally accepted device identification and coding standards and that allows unambiguous
identification of specific devices on the market’.

The UDI code is comprised of two separate identifier features; the UDI-DI (UDI- ‘Device Identifier’), which is specific to a single product (including model/version) and manufacturer, and the UDI-PI (UDI- ‘Production Identifier’), which provides traceability of a device to its production and packaging (e.g., by providing batch number etc.). The UDI-DI part of this identifier code, will be provided to a manufacturer by an issuing entity, designated by the European Commission. The most prominent of these entities is a company called GS1, who assign a manufacturer a GTIN (Global Trade Item Number) to each product that a manufacturer is looking to market. Instances whereby a UDI code is not required for a device, are limited to if a device is custom made, or when it is solely produced and intended for a clinical investigation.

Below is an example of how a UDI code consists of both the UDI-DI and the UDI-PI.


The UDI system of identifying medical devices is currently/soon to be employed in both the EU (date of application for the MDR being 26-May-2021, and IVDR being 26-May-2022), and in the US. These regulatory markets have one major difference relating to the UDI system; the requirement for a Basic UDI-DI (BUDI) within the EU. The BUDI functions as the highest level of identification for a family of products or group of devices that share the same intended purpose, risk class, essential design, and manufacturing characteristics. An example of this could be devices that come in various sizes, or packets of devices in varying quantities. The BUDI code is critical for the registration of devices into the EUDAMED databases. It functions to connect a group of devices, and to connect this group to the appropriate documentation (e.g., the technical documents, certificates, or the EU declaration of conformity document). The Basic UDI-DI does not appear on the the packaging or on the labelling of a device though. This is=where you will find the UDI-DI. A UDI-DI code can only be associated to a single Basic UDI-DI, but many UDI-DI codes can fall under one BUDI.


In summary, the UDI code system can be viewed as a means for unambiguous device identification and traceability. The level of specificity afforded by the UDI system provides the following benefits to medical device manufacturers:

  • makes traceability of devices more efficient
  • allows easier recall of devices
  • combats counterfeiting
  • improves patient safety

If you have any questions about UDIs, labelling or any other regulatory matter, just get in touch with IMed by email on alison@imedconsultancy.com or give us a call on 01295 724286

Jacob Tyson

Jacob Tyson

Medical Writer

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