UDI-DI, UDI-PI & Direct Marking Explained
Meaning & Structure
As part of the Medical Device Regulation (MDR), every medical device must be labeled with a unique identification - the UDI (Unique Device Identification). The UDI is a key issue for many manufacturers, especially since the introduction of Eudamed. In addition, the barcode must be affixed directly to the product for certain products (Direct Marking).
What does the UDI involve?
According to MDR, Annex VI Part C, the UDI is a sequence of numeric or alphanumeric characters created according to a globally recognized identification and coding standard. It enables the unique identification of an individual device on the market. The UDI is composed of the UDI-DI and the UDI-PI.
The UDI is usually applied as a barcode and in plain text on the product itself or on the packaging. Four allocation bodies have been appointed in Europe: GS1, HIBCC, ICCBBA, IFA. UDIs and basic UDI-DIs can be created according to their specifications. Each UDI-DI must be assigned exactly one basic UDI-DI.
A special rule applies to software: the UDI is assigned at the system level of the software. This requirement only applies to software that is either commercially available or is itself considered a product. You can find more information on Basic UDI, Eudamed-DI and Eudamed-ID in our blog post What is the Basic UDI-DI (Basic-UDI) & Eudamed DI/ID? Meaning & Structure.
What is the UDI-DI and how is it structured?
The UDI-DI (Unique Device Identifier - Device Identifier) is a unique numeric or alphanumeric code that is assigned to a specific product model. It serves as an access key to information in a UDI database.
Depending on the issuing authority, the UDI-DI may have different structures:
What is the UDI-PI and how is it structured?
The UDI is a numeric or alphanumeric coder used to identify the production unit of the product. The different types of UDI-PI include the serial number, the lot number, the software identification and the manufacturing or expiry date or both. Further information (e.g. country of origin) can also be included in the UDI-PI through the various allocation bodies. A few things must be taken into account.
- All relevant information on the product label (serial number, lot number, software identification, manufacturing and expiry date) must be included in the UDI-PI.
- If there is an expiry date, the date of manufacture can be omitted.
- If no expiry date exists, the date of manufacture must be included in the UDI-PI.
- Implants are subject to special requirements for the lowest packaging level.
The structure of the UDI-PI differs greatly between the various allocation offices. The exact specifications can be found on the respective homepages.
What is direct marking?
Direct Marking or Direct Part Marking (DPM) refers to the application of information such as barcodes, HRI (Human Readable Interpretation), CE marks or symbols to the product itself. This method is used in particular for reusable medical devices to ensure permanent identification throughout the entire product life cycle.
According to the MDR, reusable devices must bear the UDI carrier directly on the device itself. This applies in particular to devices that need to be cleaned, disinfected, sterilized or reprocessed between uses.
Requirement according to MDR:
- The UDI carrier must be permanently attached.
- The UDI must remain legible after each reprocessing.
- The marking must be retained for the entire service life of the product.
The obligation for direct labeling does not apply if:
- Direct marking would impair the safety or performance of the product.
- The product cannot technically be labeled directly.
These exceptions are clearly defined in the MDR and must be verifiably documented by the manufacturer.
Article 20 of the MDR specifies a CE marking on the product itself or on a higher packaging level. The minimum height of 5 mm can be deviated from for small products (see MDR, Annex V).
How should the UDI be applied?
The UDI carrier (AIDC (Automatic Identification and Data Capture) and HRI (Human Readable Interpretation), see Figure 1) may only be applied by the manufacturer to the product itself and to all higher levels of the product packaging. Shipping containers are not considered a higher packaging level.
Figure 1: Example of a label with UDI from GS1
The UDI carriers can be linear barcodes, 2D matrix barcodes or RFID (Radio Frequency Identification), among others. The UDI-DI and UDI PI can be encoded in one barcode or separately in two barcodes. The 2D matrix barcode (e.g. Data Matrix code) is usually preferred due to a lack of space, as it requires much less space than the linear barcode.
Any other text that has nothing to do with the barcode (expiry date, REF, ...) is referred to as "non-HRI text". Only the HRI indicates the content of the barcode in a human-readable form. For better readability, characters can be added according to the specifications of the issuing authority, but these are not present in the barcode. This means that the barcode and HRI contain the same information but not the identical characters. In the example above, the brackets "()" can only be found in the HRI and are not encoded in the barcode.
In exceptional cases, the AIDC or the HRI can also be omitted. For single-use class I and IIa devices that are individually packaged and labeled, a UDI carrier is only required at the higher level. However, the user must have access to the higher packaging level. In this case, a "virtual UDI-DI" is assigned for the individually packaged device, which is not maintained on the device, but as a Unit of Use-DI in the technical documentation and later reported in Eudamed.
Example:
Suction cannulas (Class IIa, single use) are sold in a pack of 30.
- The individual packaged cannula itself does not receive a UDI (but a virtual UDI-DI), (Unit of Use-DI). This means that the needles may not be sold individually.
- The 30 box is the higher level and receives the UDI-DI, which of course must be different from the virtual UDI-DI.
This means 2 UDI-DIs must be assigned, whereby only 1 UDI-DI is applied to the product. Here you can consider whether the packaging index/indicator is used in the UDI-DI.
The exact specifications for the barcode and HRI can be found on the respective homepage of the allocation offices.
What are the Timelines for UDI and Direct Marking?
Compared to the USA, not all timelines have yet expired in Europe. The "UDI timelines" apply exclusively to the application of the UDI carrier and not the definition of the UDI in the technical documentation (MDR, Article 27 (7)). For Class I devices, for example, these must already be included in the MDR technical documentation since May 2021. Class I devices that could still be sold under MDD after May 2021 are excluded here (e.g. 1+S (sterile), 1+R (reusable), ...)
When must a new UDI-DI be issued?
The MDR provides detailed information on this in Annex VI Part C 3.9:
A new UDI-DI is required whenever there is a change that could result in misidentification of the device and/or ambiguity in its traceability; in particular, a new UDI-DI is required when any of the following data elements in the UDI database are changed:
- Name or trade name,
- Product version or model,
- For single use only,
- Sterile packed,
- Sterilization required before use,
- Quantity of products in a package,
- Important warnings or contraindications: e.g. contains latex or DEHP
According to the MDR (Annex VI, Part C, Section 6.5.2), a new UDI-DI for software is required if one of the following elements changes:
- The original performance
- The safety or the intended use of the software
- The evaluation of the data
These changes include nw or modified algorithms, database structures, operating platforms and architectures or new interfaces or new channels for interoperability.
Additional special cases can be found in MDCG document 2028-1 Rev.4 Direct marking.
- Change from “Yes” → “No”: A New UDI-DI is required.
- Change from “No” → “Yes” : No new UDI-DI required, but compliance with the timelines for Direct Marking.
UDI-PI (Production Identifier)
- Changes to the date of manufacture, expiry date, LOT, or serial number do not require a new UDI-DI as long as the label does not change.
Maximum number of reuses
- A new UDI-DI is required if the maximum number of reuses changes.
Important note: There are fields in EUDAMED that cannot be changed retrospectively. If an error is made, a new UDI-DI must be assigned.
Do you still have questions?
We would be happy to support you with your UDI/Eudamed project, offer you our RA hotline or training courses. You may also be interested in our blog post:
EUDAMED and Regulation 2024/1860: Transition periods for MDR/IVDR products and requirements.
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