In my opinion it's not ever definitively determined at all, and whether it is Crohn's, pouchitis, or something else is irrelevant because it's IBD, you have it, and you need to treat it.  I have had Prometheus Blood Serum Tests, MRI Enterographies, CT Enterographies, was recommended to attempt (but rejected) the Capsule Endoscopy.  All are diagnostic tests. None really prove anything.  I had my results reviewed by expert pathologists at Mount Sinai in NYC, on the west coast, and at Yale, all said the tests were inconclusive.  They are IMHO worthless and a waste of time and money.  Just call it IBD and treat it, anything beyond that is needless stress and a complete waste of time.

Also, whether it's beyond the pouch (as in my case) merely creates a suspicion of Crohn's, but in most cases now they are finding inflammation developing above the pouch in older pouches with inflammation where bacterial overgrowth is the culprit.  This is what Dr. O said was the cause of my neoterminal ileum inflammation.  There is no valve to stop backsplash from the pouch and that is why I have inflammation just above in irregular swaths and patches.

The kicker is that even IF these tests were conclusive and you knew what you have, you still have to treat it, and most of the treatments for CD and pouchitis are the same or similar and what works for one person with the same diagnosis may not work for another.  So at the end of the day it is complete irrelevance in its purest form, and a vestige of old and outdated medical thinking to even worry about it.  Dr. O didn't worry about diagnosis, he worried about treating what I had.

All true, but I can understand your dilema, Ally, because you are diverted and wondering if pouch salvage is possible for you.

Unless they find granulomas in biopsy (diagnostic, but not common), they have to rely on all the information gathered and which way the scale is tipped. Inflammation at the anastomosis should not be considered a sign of Chron's. Cobblestoning inflammation and/or inflammation that goes into the muscular layers (including fistulas not associated with the anastomosis).

If you read the pouchitis article in the "sticky" post in the Pouchitis Forum, a description of Crohn's of the pouch is there.

Like mentioned before, Crohn's or not, you treat with whatever works. Worst case scenario- nothing works and the pouch has to go, connected or not. But, if you have Crohn's, or suspected Crohn's, you don't remove small bowel except as a last resort. You want to maintain as much as you can because you don't know what yhe future may bring.

Jan