Medical Device UDI Printing: 3 Hard Constraints on Packaging — The One Where Print Shops Most Often Fall Is the "UDI Code + Packaging Integration" Link

Last November, a Shenzhen printing company that produces in vitro diagnostic reagent packaging was sent back 120,000 IVD packaging boxes by a customer. The reason for the return was not misprinted text or incorrect colors, but that after scanning the codes in the National Medical Products Administration UDI database, the DI codes did not match the registered information. The 120,000 boxes had already been printed, die-cut, and packed with reagents in preparation for shipment. The customer's final decision was to use laser coding to cover the original barcodes and print a new set of DIs. The printing company ultimately lost 380,000 on the order.

This is not an isolated case. In the fifth year of UDI implementation, the orders for “medical device packaging” received by printing plants are entirely different in nature from those in 2021. In 2021, customers were asking whether they could print a GS1 barcode; in 2026, they are asking whether an integrated UDI solution can be provided. If printing plants continue to treat UDI as an ordinary barcode, they will run into three types of hard constraints.

Hard Constraint 1: The UDI code itself is not "a single code," but consists of two codes—DI and PI—plus a set of data

Many printing professionals assume that a UDI order is simply GS1-128 plus a string of digits when they receive one for the first time. This is incorrect. UDI consists of two parts:

If the printing plant prints only DI and not PI, or uses PI directly as the production batch number by reusing the inkjet code position from the old version, customers scanning the code in the drug regulatory authority's database will encounter a situation where "DI can be scanned, but the PI does not match the batch." This is the real reason behind the failure of the Shenzhen printing plant mentioned above—they printed only DI, while the PI used the small inkjet code printed on the side, which could not be read in the PI section during regulatory database scanning and verification.

More subtly, DI is not something the customer can make up on a whim. It must first be registered in the NMPA UDI database (udid.nmpa.gov.cn) through "DI registration" and obtain authorization before printing can begin. Printers often skip this step—when a customer says, "Print this code for me," the printer does not ask, "Has this code been registered in the database?" As a result, the printed code cannot be scanned to retrieve any information.

Hard Constraint 2: The UDI code cannot simply be “printed wherever there is space on the package”

Article 5.3 of the “Unique Device Identification System Rules,” released in April 2026, explicitly states that the UDI carrier should be printed on a location on the sales packaging where it can be read by scanning devices. What does “readable by scanning devices” mean? These are the 3 pitfalls most commonly encountered by printing plants:

A Suzhou printing factory that produces orthopedic implants received an order from Johnson & Johnson to manufacture the products on its behalf last year. The customer’s artwork called for a “gold-foil LOGO in the upper-right corner + a UDI code below,” but the reflected light from the gold foil reduced the UDI code’s contrast from 4.5:1 to 2.8:1. Its readability fell to Grade C under the ISO 15416 standard—classified as “unreadable” by the drug regulatory authority’s GS1 system. The entire batch was ultimately reworked by moving the UDI code to a non-gold-foil area.

The printer should treat the UDI placement as “part of the structural design”—before plate development, the printer should ask the customer for 3 items: the packaging dieline, the minimum UDI code size, and a screenshot of the scan verification. Plate development should proceed only when all three items are available and should stop if any one is missing.

Hard Constraint 3: The readability level and printing accuracy of UDI codes must undergo "dual verification"

Conventional barcode printing plants focus only on whether the code can be scanned, whereas UDI codes also require determining the grade of the scan result.

ISO 15416 classifies barcode readability into five grades: A, B, C, D, and F. The drug regulatory authority's UDI system requires a minimum grade of C, with grade B or above recommended. If a printing facility produces UDI barcodes according to the standards for ordinary packaging barcodes, the resulting grades often fall near the threshold of C—during on-site inspection, even a handheld scanner positioned at an unfavorable lighting angle can result in an immediate failure.

Key parameters affecting the rating:

More subtly, there is “print registration accuracy”—offset printing has a registration accuracy of ±0.05mm, HP indigo digital printing is ±0.02mm, and flexographic printing on film is ±0.08mm. If the bars of a UDI code are 0.25mm wide, a ±0.08mm flexographic printing deviation means that the bar width fluctuates between 0.17-0.33mm, and the narrowest bars may be only 0.17mm—making them impossible for a scanner to read directly.

3 Checklists for UDI Orders Received by Packaging Manufacturers

First step: Ask these 3 questions before the customer provides the codes

Step Two: Confirm 3 positions before plate making

Third step: Conduct 3 types of sampling before shipment

Further Reading