FDA Issues Recommendations for the Form and Content of a Unique Device Identifier

August 1, 2016

On September 24, 2013, the FDA published the UDI Rule, which established a standardized identification system for medical devices used in the United States.  Under this rule, the label and packages of every medical device distributed in the US is required to bear a unique device identifier (UDI).  UDIs can only be issued by an FDA-accredited issuing agency operating a system abiding by the international standards listed under 21 CFR 830.20.

According to the FDA, “the UDI must be presented in two forms on the label and device packages: easily readable plain-text and automatic identification and data capture (AIDC) technology (21 CFR 801.40(a)). When a device must bear a UDI as a direct marking, the UDI may be provided through either or both easily readable plain-text and AIDC technology forms, or any alternative technology that will provide the UDI of the device on demand (21 CFR 801.45(c)).”  In addition, the Agency states that labelers must submit all medical device product information to its Global Unique Device Identification Database (GUDID).

The UDI Rule created a unique system making it possible to quickly and accurately identify a device and some of the key attributes affecting its safe and effective use.  Furthermore, “the UDI Rule specifies that the labeler, as defined under 21 CFR 801.3, is responsible for complying with the UDI labeling (21 CFR 801 Subpart B) and GUDID submission (21 CFR 830 Subpart E) requirements.”

On Tuesday, July 26th, the FDA issued a draft guidance, entitled “Unique Device Identification System: Form and Content of the Unique Device Identifier (UDI),” in which the Agency describes the two forms of a UDI and clarifies the UDI’s content.

What is a UDI?

Title 21 of the Code of Federal Regulations section 801.3 defines a UDI as “an identifier that adequately identifies a device through its distribution and use.”  A UDI must meet the requirements of 21 CFR 830.20 (Requirements for a unique device identifier), as well as 21 CFR 801.40 (Form of a unique device identifier), and is composed of:

  1. A device identifier (DI)
  2. Typically one or more production identifiers (PIs) when included on the device label
  3. The data delimiters for the DI and PIs included in the UDI.

Forms of a UDI

The UDI must be presented on the label of the device and on each device package in both of the following forms:

  1. Easily readable plain-text
  2. AIDC technology

FDA’s draft guidance also states that “for devices required to be directly marked with a UDI under 21 CFR 801.45, the UDI may be provided through either or both forms, or any alternative technology that will provide the UDI of the device on demand (21 CFR 801.45(c)).”

Easily Readable Plain-Text

According to the FDA, “’easily readable plain-text’ means the legible interpretation of the data characters encoded in the AIDC form of the full UDI, including the data delimiters.”  This form of the UDI should include the DI, production identifiers (PIs), and data delimiters contained in the UDI; additionally, the easily readable plain-text form of the UDI should only contain the characters specified under ISO/IED 646.  Furthermore, according to FDA’s draft guidance, this form of the UDI “may be presented as a single line or multiple lines of text and should be displayed below or near the AIDC technology form of the UDI.”


AIDC is “any technology that conveys the UDI or the DI portion of a UDI of a device in a form that can be entered into an electronic patient record or other computer system via an automated process.”  According to the UDI Rule, there are no specific forms of AIDC or specific AIDC technologies required to be present in the UDI; however, the draft guidance states that the AIDC form of the UDI should be in a format that can be read by either a bar code scanner or some other AIDC technology.

FDA’s draft guidance states the following with regards to the AIDC form of the UDI:

  • “Due to space limitations or other reasons, the AIDC form of the UDI may be split into multiple segments.”
  • “The labeler may choose to use more than one type of AIDC technology form to assist users who may be employing different methods of UDI capture technology.”
  • “If a labeler choses a bar code form of AIDC, the bar code form of the UDI should be tested for print quality.”
    • FDA advises labelers to discuss print quality requirements with their FDA-accredited issuing agency.

“If the UDI presented in the AIDC technology format is not visible to the human eye upon visual examination of the label or device package (e.g., RFID technology), the label or device package must disclose the presence of AIDC technology. It is up to the discretion of the labeler to determine how best to disclose the presence of AIDC technology that is not evident upon visual examination. The FDA does not require a specific type of marking or a symbol, providing the labelers greater flexibility and reduced burdens.”

Content of UDI

Technically, a UDI is composed of only a single DI and one or more of the five PIs listed in 21 CFR 801.3 and 801.40(b), as well as the data delimiters for the DI and PIs.  The draft guidance notes that, although some FDA-accredited issuing agencies may allow non-UDI elements (i.e., quantity) to be included in the UDI carrier, the FDA does not recognize any additional non-UDI elements as being part of the UDI.

With regards to the content of the UDI and the UDI Rule, FDA states the following:

“The UDI Rule does not include any additional requirement to place any of the five elements that would be considered a PI on the label. There are some situations where a UDI may comprise a DI only. The UDI of a class I device, for instance, is not required to include a PI. However, it is important to note that for other than class I devices, if one or more of the five PIs defined under 21 CFR 801.3 are included on a device label, the UDI must include each of the PIs that appears on the label (21 CFR 801.40(b)).”

For additional details on FDA’s recommendations for the form and content of the UDI, view the full draft guidance.

Are you developing a medical device or other FDA regulated product? We can help you obtain the desired approval from the Agency.  To learn more about our services and how we can help you, contact us today.


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