It is so easy to make a web site look professional. It is difficult to know how much credence to give to posted claims. You have to carefully read between the lines.
There was a note in the detailed description of the IBS diagnostic test that caught my eye. It says "Currently, Food and Drug Administration (FDA) approval is not required for IBS Diagnostic testing performed by Prometheus." In other words, currently there are no standards for IBS blood tests, hence there is little evidence that a collection of blood tested biomarkers can be a reliable indicator of IBS. Also, according to a footnote the "data on file" are what they use to make claims. The analytical and statistical methods and in particular, the proprietary pattern matching algorithm, is not referenced with a single peer reviewed research paper.
I would rely on a GI doc's ability to diagnosis IBS. Maybe s/he can figure out what the data from this lab means. As for giving advice on how to manage IBS there is lots of room for improvement in every profession dealing with IBS
-------------------- STABLE: ♂, IBS-D 50+ years - Science of IBS