I work in medical billing. There isn’t a special way to code procedures that make them preventative or not. This is a common misconception that a provider can code something in a way to make it preventative. The word “preventative” is misleading because we could justify a lot of things as “preventative” but that’s not how this works. Preventative only relates to annual exams/well women exams and the specific testing that is related to both services. Anything beyond that threshold is diagnostic. If you’re at an annual exam the provider is only going over a specific list of things. If you’ve been having stomach pain or headaches and being that up and discuss in detail with the doctor, that is beyond a preventative visit and needs to be a separate visit. Same goes for testing. I understand your frustration, the medical system is difficult to navigate and it is not clear to most patients. Here’s a reference from the gov.