Manufacturers operating across the EU, UK and USA quickly encounter a set of similar but distinct terms relating to Unique Device Identification (UDI).
UDI, UDI-DI, UDI-PI and the Basic UDI-DI often cause confusion, and understanding their differences is essential for compliant labelling, packaging, regulatory submissions and traceability.
This article breaks down each term clearly and explains how they fit into global medical device regulation.
What Is UDI?
The Unique Device Identifier (UDI) is essentially a digital fingerprint for a medical device.
It provides a structured code that allows regulators, manufacturers and even patients to identify:
- a specific device model, and
- in some cases, a specific unit, lot, batch or serial number.
The primary purpose of UDI is traceability particularly useful when managing recalls, field safety actions or post-market surveillance.
A complete UDI is made up of two parts:
- UDI-DI (Device Identifier)
- UDI-PI (Production Identifier)
UDI-DI: The Device Identifier
The UDI-DI is the static portion of the UDI.
It represents the specific:
- model number
- version number
- design variant
This identifier only changes when the manufacturer makes a significant change affecting the device’s safety or performance.
In practice, the UDI-DI is the anchor that ties the device to its regulatory record in systems such as:
- FDA GUDID (USA)
- EUDAMED (EU)
- MHRA registration portal (UK)
UDI-PI: The Production Identifier
The UDI-PI is the dynamic part of the UDI.
It changes with each production cycle and includes:
- lot or batch number
- serial number
- manufacturing date
- expiry date
The UDI-PI allows manufacturers to pinpoint exactly which units may be affected by defects or recalls.
How UDI Appears on Devices and Packaging
Manufacturers must present the UDI in two formats:
- Human-Readable Interpretation (HRI) – plain-text code
- Automatic Identification and Data Capture (AIDC) – barcode or data matrix
However, exceptions exist for devices where direct marking is impractical:
Small surgical instruments
These may only include:
- AIDC alone, or
- HRI alone, or
- a full UDI placed on higher-level packaging.
Software and AI medical devices
Software still requires UDI, typically displayed on:
- startup screens
- “About” or “Device information” pages
AIDC barcodes are not required for digital-only products, but the HRI including the software version must be accessible to users.
If software is distributed on a physical medium (CD, USB etc.), the full UDI must appear on the packaging.
UDI Databases Around the World
Manufacturers must upload the UDI-DI into the correct regional database:
- USA: GUDID (Global Unique Device Identification Database)
- EU: EUDAMED
- UK: MHRA registration system
These systems link the UDI-DI to regulatory submissions, certificates and device listings.
The Basic UDI-DI (EU-Only)
The Basic UDI-DI is unique to the EU MDR and EU IVDR. It does not appear on the device, packaging or barcode. Instead, it functions as a higher-level grouping code, connecting devices that share:
- the same intended purpose
- the same risk class
- similar design or manufacturing characteristics
It is used for:
- EUDAMED registration
- Notified Body certificates
- technical documentation organisation
The Basic UDI-DI is an umbrella identifier, not a label element.
Where Do UDIs Come From?
UDI-DI and Basic UDI-DI codes must be obtained from a recognised issuing agency.
The major global agencies include:
- GS1 (most common)
- ICCBBA
- HIBCC
- IFDMA
These organisations generate the required identifiers and help manufacturers structure compliant barcodes and device labelling.
The UDI-PI, however, is created directly by the manufacturer because it contains production-specific information.
Why UDI Matters
Manufacturers must understand UDI because it impacts:
- regulatory submissions
- compliant labelling and packaging
- database registrations (GUDID, EUDAMED, MHRA)
- quality management systems
- traceability in recalls and PMS
With each region having slightly different requirements and software and small devices adding further nuance, manufacturers should have a clear internal procedure governing UDI assignment for every product line.
Clear UDI processes reduce regulatory risk and ensure consistent global compliance.
LFH helps medical device manufacturers navigate UDI requirements across the EU MDR, UK MDR and FDA frameworks. From UDI assignment and labelling strategy to regulatory submissions and EUDAMED readiness, our experts ensure your products are compliant, traceable and audit-ready.
FAQs – UDI Explained
Is UDI mandatory in the EU, UK and USA?
Yes. Each region has UDI requirements, though implementation timelines and databases differ.
Do software medical devices need a UDI?
Yes. It must appear on the device’s interface in human-readable form, even without packaging.
Is the Basic UDI-DI printed on the product?
No. It exists only in documentation, certificates and EUDAMED records.
When should a new UDI-DI be assigned?
Only when a significant design or version change affects safety or performance.
