Bowel disease can change over the course of time and the diagnosis of it is not really relevant any more since many of the treatments are the same. There are many people who had UC and later manifested either “Crohn’s” or Crohn’s like inflammation in areas where it didn’t previously exist. J Pouches change your anatomy and also don’t have an escape hatch as the colon did so the manifestation of inflammation north or above the j pouch is no longer a real surprise. Many people never have it, some get it over a decade after J Pouch surgery like me. In the end what you call it doesn’t matter, what matters is responsiveness to treatments that are largely the same. I was far sicker with UC in the 1970s and 1980s than I have been with Crohn’s since 2007 and I am very satisfied with my current status. It’s due to effectiveness of treatment. No matter what you call IBD it’s either treatable or not so focus on that and not semi-arbitrary labels.
The amount of energy wasted over worrying about a diagnosis which is incapable of being certain beyond reasonable medical certainty is quite frankly astonishing to me. I understand insurance companies operate at a Neanderthal level of understanding and need diagnosis codes but most doctors actually understand this and play the game to get coverage for the patient based on their Hippocratic duties. So what they say doesn’t really have applicability to the reality of the situation beyond insurance coverage gaming.