Human compatibility testing can feel like navigating a maze. One small design change can lead to unexpected testing requirements in completely different areas. In his latest article for Medical Product Outsourcing (MPO), StarFish Medical Project Engineer Nigel Syrotuck breaks down the hidden interconnections that make verifying compatibility so challenging.

Using a fictional device—the Gluco-Quick—Syrotuck illustrates how testing for endotoxins, sterility, bioburden, biocompatibility, cleanliness, aging, and packaging must follow a carefully considered sequence. A simple change, such as switching sealing materials, might seem minor. Yet it could require retesting for biocompatibility, sterility, or cleanliness.

To help developers avoid these pitfalls, the article explores key standards such as ISO 10993 (biocompatibility), ISO 11737 (sterility), and ASTM F1980 (accelerated aging). These provide a strong foundation for testing. However, even the best standards can’t fully solve what Syrotuck calls the “chicken-and-egg paradox.” Should you test sterility before or after packaging? Does cleaning happen before biocompatibility testing—or after?

Throughout the article, Syrotuck encourages early testing on high-risk components. He also recommends validating packaging and environments midstream, followed by final testing on the fully assembled product. By taking this strategic approach, developers can reduce risk and avoid unnecessary delays.

Human compatibility testing isn’t linear. But with a thoughtful verification plan, teams can stay ahead of surprises and maintain compliance. The article is essential reading for engineers, QA/RA professionals, and anyone managing medical device testing.