The Prometheus test is controversial (and expensive!). For example, Cleveland Clinic doesn't use it -- they don't think it's reliable enough. I had a Prometheus test done and it said that I don't have IBD at all. Uh huh, OK...
I think you are misinformed about
the CRP -- most IBDers, whether they have UC or Crohn's, will have elevated CRP during a flare. It's just a blood marker for systemic inflammation.
Biopsies taken while your colon is still inside can only capture the mucosal layers... otherwise taking a biopsy would be the equivalent of perforating your colon. That's why post-surgical pathology is more definitive. It's still not 100% though. Crohn's colitis can mimic ulcerative colitis by only involving the mucosa, starting at the rectum and spreading upwards, only affecting the colon, etc. The truth is that you can definitely have Crohn's, but everything else is only what it is "until proven otherwise."
dx'ed UC pancolitis 5/12
past meds: asacol hd, VSL#3, apriso, rowasa, xifaxan, 6mp, cortifoam, pentasa, cimzia, canasa, butyrate, flagyl, cipro, prednisone, remicade, methotrexate, cholestyramine, cortenema
current meds: none!
step one: colectomy, end ileo 1/16/13
step two: j-pouch construction, loop ileo 5/1/13
step three: takedown 7/31/13