What Are UDI Codes and Why Were They Introduced?

The Unique Device Identification (UDI) system provides standardized labeling so that each medical device can be unambiguously identified. It was introduced to enhance post-market safety processes, streamline adverse event reporting, and improve regulators’ ability to track devices. In healthcare settings, UDI also helps optimize purchasing, waste disposal, and reduces medical errors and counterfeiting. By marking devices with UDI, manufacturers ensure precise traceability through the supply chain, enabling rapid recalls of non-compliant products and enhancing patient safety. Under the MDR and IVDR, manufacturers must now assign a UDI to their devices.

Basic UDI-DI

First, the manufacturer assigns a Basic UDI-DI, which uniquely identifies a group of devices with the same intended purpose and risk class. The Basic UDI-DI appears on the EU Declaration of Conformity, the CE certificate, the technical documentation, and in EUDAMED—but not on the device itself. Assignment of the Basic UDI-DI is mandatory for all MDR and IVDR devices. For devices requiring notified-body involvement, the Basic UDI-DI must be issued before submitting the conformity assessment application.

Key Components of the UDI

The full UDI comprises two parts:

  • UDI-DI (Device Identifier): A fixed code (e.g. EAN) unique to a specific device model, size, or configuration.
  • UDI-PI (Production Identifier): Variable production data defined by the manufacturer—batch or lot number, manufacture date, expiration date, serial number, or software version.

Rules for UDI-PI:

  • Implantable devices must include a serial number; other implantable types may use batch or serial.
  • Any serialization, software version, or expiry date printed on the label must be part of the UDI-PI.
  • Manufacture date need only be included if it is the sole date on the label.

Issuing a New UDI Code

Any change that could cause device misidentification—trade name, version, model, packing for sterile supply, sterilization method, pack quantity, critical warnings, contraindications, or intended use—requires assignment of a new UDI-DI.

Who Places the UDI and Where?

The manufacturer assigns UDIs and places them on the device or its label/packaging at every level except transport containers. Distributors and importers must verify correct UDI labeling. Exemptions: custom-made devices, clinical-investigation devices, performance study kits, and demonstration units. For reusable devices, UDI must be permanent and legible throughout the product’s lifecycle unless it would compromise safety or functionality, or cannot be technically applied.

Storing UDI Codes

Manufacturers must archive and update all UDI-DI and UDI-PI. Healthcare institutions must retain UDI records for Class III implantable devices they handle. Repackagers/relabelers must preserve the original manufacturer’s UDI.

Quality management systems must define procedures to verify UDI assignment and ensure consistency with EUDAMED registration.

UDI in EUDAMED

In EUDAMED, manufacturers register each device’s Basic UDI-DI and all variant UDI-DIs. UDI-PI codes need not be uploaded but must remain archived by the manufacturer. The public UDI database will not expose any confidential device data.

Deadlines for UDI Labeling

Per MDCG 2021-19, deadlines for placing UDI on device packaging under MDR:
• Class III & implantables: by 26 May 2021
• Class IIa & IIb: by 26 May 2023
• Class I: by 26 May 2025
Reusable device deadlines are offset by two years (IIa/IIb by 2025, Class I by 2027).

Under IVDR:
• Class D: by 26 May 2021
• Class C & B: by 26 May 2023
• Class A: by 26 May 2025.

Available UDI Formats

UDI carriers may use AIDC technologies—1D/2D barcodes, DataMatrix, RFID, chip cards—or HRI (human-readable interpretation). HRI uses standardized Application Identifiers (AIs), e.g. GS1 uses AI (01) for UDI-DI, (10) for batch, (17) for expiry, (21) for serial, etc.

How to Create a UDI

UDIs are issued by one of four EU-designated issuing agencies: GS1, HIBCC, ICCBBA, or IFA. These bodies provide UDI-DI ranges and Basic UDI assignment. Manufacturers generate UDI-PI per production run. A variety of vendors can supply labeling technologies and equipment. UDI must remain legible throughout normal use, verified per ISO 20471 or equivalent guidance.

Special Considerations & Exemptions

  • No UDI on transport packaging.
  • If unit package space is limited, UDI may be on the next higher packaging level.
  • For single-use Class I/IIa devices sold individually, UDI-carrier on secondary packaging suffices unless patient access necessitates unit labeling.

Procedure packs and systems require UDI on the outer packaging; individual single-use items within need not bear UDI. Software devices receive UDI at the system level; significant software updates require a new UDI-DI, minor patches only new UDI-PI. Software UDI can appear on physical media or via user interfaces or API, with HRI displayed on screen if no physical label.

How Pure Clinical Can Help with UDI Implementation

  • Interpret MDR/IVDR UDI requirements (Articles 27, Annex VI).
  • Advise on issuing agency selection and UDI-DI/Basic UDI assignment.
  • Define UDI-PI schema for batch, serial, expiry, and manufacture dates.
  • Integrate UDI processes into your QMS and EUDAMED submission.
  • Validate label layout and AIDC readability per ISO/IEC standards.
  • Train staff on UDI workflows and regulatory deadlines.