FDA’s Final Guidance on Unique Device Identifier

Zuhal Reed, Esq. | Risk Management Senior Staff Attorney | Medmarc

October 5, 2021

On July 7, 2021, FDA released their final guidance document regarding the content and forms of Unique Device Identifiers (UDIs). The recommendations are written specifically for labelers of medical devices as well as stand-alone software that is regulated as a medical device. This guidance focuses primarily on form and content recommendations. The document discusses the two forms of a UDI, the use of data delimiters, and recommendations for labeling stand-alone software.

UDI is a numerical identification on a device that is meant to identify that device throughout the entire distribution chain. Its objective is to promote accurate reporting of adverse events, to create more effective management of device recalls, and to simplify post-market surveillance. The party responsible for the accuracy of the UDI is the labeler, which is the party that applies or modifies the label. A distributor that is not involved in label application or modification is not a labeler.

Per 21 CFR 801.40, all medical devices must have two forms of their UDI. That is, a medical device must bear: (1) an easily readable plain-text form that is alphanumeric and (2) an automatic identification and data capture (AIDC), which is a barcode or 2D code. The 2D code serves as an easy to detect identification on the device.

 The document also discusses the use of data delimiters and the order in which data should be presented. Technically speaking, data delimiters allow you to specify the boundaries in a stream of data.  This means that, a labeler can include a specific character or a set of characters to distinguish between certain elements to help with the identification of particular data elements in the UDI. Delimiters are central to UDI comprehensibility and utility[i]. FDA further explains that “data delimiters allow the UDI to be distinguished and captured separately from any non-UDI elements that may be represented in the UDI carrier. In addition, if non-UDI elements are included in the UDI carrier, separate data delimiters for these non-UDI elements should be included. Without appropriate data delimiters to identify non-UDI elements, individuals may not be able to use the easily readable plain-text form of the UDI to identify a device and computer systems may not be able to capture accurately the UDI in AIDC form via an automated process.” It is important to note that data delimiters are actually not discussed in the FDA rules nor are they necessarily a part of the device’s UDI. Rather, they are used as a means to clearly separate different parts of the UDI.

This final guidance document also discusses recommendations for labeling of stand-alone software. FDA notes that some stand-alone software is not distributed in packaged form and as such, the UDI should be provided through an easily readable plain-text statement that appears on screen when the software is started or displayed through a menu command.

This document will hopefully bring some long-awaited guidance regarding the implementation of UDI requirements.  As a reminder to labelers, guidance documents are intended to provide information and do not have the force of law.


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