To test medical device biocompatibility, manufacturers often use USP procedures such as the USP In Vivo Biological Reactivity Tests (Class I-VI Plastics Tests). The Class Plastics tests consist of various combinations of the USP Intracutaneous Test and the USP Systemic Injection Test, using one or more combinations of four extracting media. The Class IV and Class VI tests also include the USP Implantation Test.

While Class Plastics tests have some value in a biocompatibility testing program, a full Class VI test is rarely needed for a medical device. As a general rule, the Blue Book Memo and ISO documents take a broader and more thorough view of biocompatibility than does the U.S. Pharmacopoeia, and they supersede the USP for evaluating which studies to submit to FDA in support of product registrations.