UDI Barcode Structure

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UDI Code 128As the FDA rule rolls out, there is a lot of confusion about the UDI barcode. What is required? Where must it be shown? How is it structured? For reasons we don’t completely understand, it is very difficult finding answers to these very basic questions.

The UDI or Unique Device Identification is, as the name implies, a string of alphanumeric data displayed in barcode form to uniquely identify a medical device. The manufacturer of the device is responsible for both assigning the data string and making sure it is present on the device and that is scans correctly.

A UDI barcode is usually comprised of two parts, a DI or device identifier and a PI, a production identifier. Think of the DI as a UPC which identifies a class of products such as a can of Coke(R). Every one of millions and millions of cans (or medical devices) bear the exact same number. In fact the UPC (AKA GTIN 12) is the very same thing as the DI in the UDI system.

If your medical device is marked and sold only with a UPC (GTIN12), that is all that is required and your device is already FDA compliant. However if your device is also marked with an expiration date, you are required to include the PI portion of your UDI barcode.

Think of the PI as the portion of the USI that makes it truly unique to your device. It can include up to 5 types of data:

  • Expiration dataUDI Data Matrix
  • Bath or lot number
  • Serial number
  • Manufacturing date
  • Distinct identification code (identifies the donor of human cell tissue products)

Each of the PI components has a prefix number which appears in parentheses in the human readable interpretation adjacent to the barcode. This alerts the scanner that am expiration data or batch number will follow. And each component has a specified number of characters in its defined field of data. Also, dates must be presented in exactly the right sequence, starting with a four digit year, two digit month and two digit day.

The idea behind the PI is to identify anything critical to making a possible product recall as efficient and effective as possible, thereby minimizing the scope of a recall while maximizing its speed and accuracy. Thus a kit such as a drug testing kit or a first aid kit which contains many component parts will bear a UDI barcode and every component part will also bear a UDI barcode.

Devices that are implantable or on which a self-adhesive label would not survive such as an autoclaved surgical instrument must have the UDI barcode direct part parked. Often this is done with a laser marking device or a chemical etching process.

As always your comments are welcome, as well as your experiences or observations with the UDI system.


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Showing 5 comments
  • Donna L Barnes

    Great article John, makes it simple to understand.

    • John Nachtrieb

      Thank you!

  • Darryl Zurn

    Hi John. The second barcode, the GS1 Data Matrix, has a couple problems if it were a real UDI barcode.

    • The human-readable AI (01) for the GTIN only shows 13 digits, it’s missing the Check digit. The barcode content has the full GTIN
    • The date formats are different from what you described in the article itself. The EXP date should be 2016-12-31, and the human-readable date should be (17)161231. This is a big difference for many companies that were already barcoding their products but with different date formats.
    • The GTIN starts with a 1, so it is NOT a variable-quantity trade item. In other words, the GTIN is for an item with a pre-defined quantity (always 100 per box for example). The Quantity field is only needed if you are selling something like cabbages, which come 10-12 cabbages per crate, and QTY is used to show that there are 11 cabbages in THIS crate. If we aren’t selling cabbages, then QTY (30) should be removed.

  • Denise Chaney

    What are and where do you get the numbers in parenthesis? We are ready to start
    creating our bar codes but are stumped by this and have looked everywhere.

    • John Nachtrieb

      Typically the special characters are inserted by your barcode design software, but you can also key them in manually using an ASCII or Hex translation chart. You are definitely going to want to verify your barcodes or get a test lab to do so if you go the latter route or at very least have your trading partner(s) sign off on them.

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