A UDI (Unique Device Identifier) is a code, in both plain-text and machine-readable (barcode or RFID) form, that a medical device labeler assigns to identify a device through distribution and use. In the United States it is required under the FDA’s Unique Device Identification System, codified primarily at 21 CFR Part 830, with device labeling requirements in 21 CFR 801 Subpart B. For research administrators, lab managers, and procurement/supply-chain staff, UDI matters less as a labeling technicality and more as the identifier system that lab and hospital purchasing, inventory, and recall-tracking systems now build on.
What a UDI actually contains
Every UDI has two parts:
- Device Identifier (DI) — a fixed, mandatory segment that identifies the labeler (manufacturer) and the specific version or model of a device. The DI does not change unless the device’s labeling changes in a way that affects its intended use, performance, or safety.
- Production Identifier (PI) — one or more variable segments identifying, where applicable: lot or batch number, serial number, expiration date, date of manufacture, and, for human cells, tissues, and cellular and tissue-based products (HCT/Ps), a distinct identification code.
Together, DI+PI let a specific unit of a specific device be traced from manufacture through a specific patient or point of use — the same DI/PI split that underlies most modern medical-device recall and adverse-event tracing.
Who issues UDIs and how they’re structured
Labelers don’t invent their own numbering scheme. They obtain DIs through one of the FDA-accredited issuing agencies, each of which operates its own numbering standard:
- GS1 — issues GTIN-based device identifiers, the same organization behind retail/supply-chain barcoding generally.
- HIBCC (Health Industry Business Communications Council) — issues Health Industry Bar Code (HIBC) identifiers, historically common for surgical and lab-supply items.
- ICCBBA — issues ISBT 128 identifiers, used primarily for blood, tissue, and cellular therapy products.
The barcode or RFID tag on a device’s label encodes the UDI in one of these standards’ symbologies, so the same physical scanner/parsing logic used for general lab and inventory barcoding (see our guide on barcode and RFID labeling for lab sample and inventory tracking) can typically read a UDI carrier as well, provided the receiving system is configured to parse GS1/HIBC/ISBT syntax correctly.
GUDID: the public UDI database
Labelers submit device records to the FDA’s Global Unique Device Identification Database (GUDID), the reference database of DI records (not PI — GUDID holds device-level data, not unit-level lot/serial tracking). GUDID data is publicly searchable through AccessGUDID, hosted by the National Library of Medicine. A GUDID record typically includes the DI, brand name, device description, labeler (company) name, FDA product code, whether the device is sterile/single-use/an implant/an MRI-safety-labeled device, and package configuration data. For procurement and value-analysis staff, AccessGUDID is the authoritative place to confirm what a scanned or printed DI actually refers to before it’s entered into a purchasing, inventory, or EHR system.
Why UDI matters for lab and hospital procurement/supply chain
UDI was designed primarily as a patient-safety and adverse-event-tracing mechanism, but it has become infrastructure that procurement and supply-chain systems depend on:
- Recalls and safety communications. A DI-level or lot/serial-level (PI) match against GUDID and FDA recall data lets a facility identify exactly which units on its shelves or already in use are affected, rather than pulling an entire product line on a brand-name match alone.
- Purchasing and contract data integrity. Group purchasing organizations (GPOs), value analysis committees, and ERP/materials-management systems increasingly key device catalog data to the GS1/HIBC/ISBT device identifier rather than a vendor-specific item number, reducing duplicate or mismatched catalog entries across suppliers. See our guide on the value analysis committee approval process and on GPO purchasing arrangements for how device data feeds those workflows.
- EHR and implant registries. Many EHR systems now capture the UDI (not just a free-text device description) in the patient record at the point of use for implants and other devices, supporting more precise post-market surveillance and registry reporting.
- Inventory and expiration management. Because the PI can carry lot number and expiration date in machine-readable form, UDI scanning supports automated first-expired-first-out inventory rotation in a way that a brand-only barcode does not.
Compliance timeline: who has to comply, and by when
The FDA’s UDI rule, finalized in 2013, phased in compliance obligations by device risk class over several years rather than all at once, with the highest-risk devices required first:
- Class III devices (highest risk, e.g. many implants) were the first required to bear a UDI on their label and have data submitted to GUDID.
- Implantable, life-supporting, and life-sustaining devices across other classes followed on a subsequent compliance date.
- Class II devices had a later compliance date.
- Class I and unclassified devices were the last tier, with FDA granting additional exceptions and extensions for certain low-risk and legacy device types along the way.
Because FDA has granted device-specific exceptions, alternatives, and enforcement-discretion extensions since the original rule (particularly for Class I devices and certain combination products), the current compliance status for any specific device type should be confirmed against FDA’s own UDI guidance and GUDID rather than assumed from the general class-based schedule above — the original phase-in dates are a starting reference point, not a substitute for checking the device-specific current requirement.
UDI vs. other device/product identifiers
UDI is sometimes confused with other identifier systems procurement staff encounter:
- NDC (National Drug Code) identifies drug products, not devices, and is FDA’s separate pharmaceutical identifier system — some combination products carry both.
- HCPCS/CPT billing codes identify a procedure or service category for reimbursement purposes; they are not device-specific and do not distinguish between manufacturers, models, or lots the way a UDI does.
- A manufacturer’s internal catalog/SKU number is vendor-specific and not standardized across suppliers, which is precisely the fragmentation problem UDI and GS1/HIBC/ISBT-based catalog data are meant to resolve for cross-vendor purchasing systems.
Frequently asked questions
What is UDI in a medical device?
UDI (Unique Device Identifier) is a two-part code — a fixed Device Identifier (DI) plus one or more variable Production Identifiers (PI, e.g. lot, serial, expiration date) — that the FDA requires most medical device labelers to assign, mark on device labels/packaging in machine-readable form, and submit DI-level data for to the GUDID database, under 21 CFR Part 830 and 21 CFR 801 Subpart B.
What are the UDI requirements for medical devices?
At a minimum: labelers must obtain a DI from an FDA-accredited issuing agency (GS1, HIBCC, or ICCBBA), mark the device label and, where applicable, the device itself with the UDI in both human-readable and automatic-identification (barcode/RFID) form, and submit the associated device record to GUDID. Exact obligations (labeling, direct device marking, GUDID submission) and their compliance dates vary by device risk class and by any device-specific exceptions FDA has granted, so they should be confirmed against current FDA UDI guidance for the specific device type in question.
Is a UDI the same as a barcode?
Not exactly. The UDI is the identifier (the DI+PI data); the barcode (or RFID tag) is one of the carrier mechanisms used to encode that identifier in machine-readable form on the label. The same UDI data could in principle also appear as plain text without a barcode, though FDA’s rule specifically requires an automatic identification and data capture (AIDC) technology — in practice almost always a barcode — alongside the human-readable form.
Where can I look up a device’s UDI record?
AccessGUDID, maintained by the National Library of Medicine, is FDA’s public interface to the GUDID database and the authoritative place to search DI-level device records by DI, brand name, or company name.
