UDI: What the Code on the Label Actually Contains

UDI is the system for identifying a medical device unambiguously from manufacture through distribution and use. It exists because devices that look alike are not alike, and because a recall is only as good as your ability to say which units are affected.

The two halves of a UDI

Device Identifier (DI). Fixed. Identifies the version or model and the labeller. This is the part that goes in the database and never changes for that model.

Production Identifier (PI). Variable. Any combination of lot or batch number, serial number, expiry date, manufacturing date, and for HCT/Ps the distinct identification code.

So a UDI is DI + PI, and the DI is the searchable key. Our UDI lookup tool resolves the DI portion, which is why pasting a full barcode still works: the DI is extracted from it.

How it appears on the label

Twice, in two forms:

• AIDC, automatic identification and data capture. The barcode or RFID a scanner reads.
• HRI, human readable interpretation. The same content printed so a person can read it.

Both are required unless an exception applies, and the HRI has to match what the carrier encodes. A mismatch between the two is a real and findable error.

Issuing agencies

FDA accredits issuing agencies rather than assigning codes itself. GS1, HIBCC and ICCBBA are the ones in use. GS1 is the most common, and its format is why a barcode reads as (01)00616258008684(17)261231: the parenthesised numbers are application identifiers, 01 being the GTIN and 17 the expiry.

GUDID and EUDAMED are separate systems

The US GUDID holds the DI record and its attributes: brand name, model, sterilisation, MRI safety, sizes, the 510(k) or PMA that cleared it.

The EU EUDAMED UDI database is a different system with different fields, under EU MDR. It requires a Basic UDI-DI, a concept the US system does not have: an identifier for a group of devices sharing the same intended purpose and design, sitting above the DI as the key that links a device family to its certificate and technical documentation.

Registering in one does not register you in the other, and the Basic UDI-DI has no US equivalent to copy from.

Where it goes wrong

• The label and the database disagree. GUDID says one thing, the artwork says another, usually after a change that updated one and not the other.
• A new DI was not issued when a change required one. A change to a version or model needs a new DI, and deciding it did not is a decision someone has to own.
• The symbols and the UDI carrier compete for space, and something gets dropped in artwork.