Can a biopsy differentiate between UC and Crohns?

When a colonoscopy is done and there is inflammation, how do they know if it's UC or Crohns?

I'm asking this because, I've had a diagnosis of UC for 11 years now, all 6 of my colonoscopies have came back as that diagnosis and I've always had the disease in my sigmoid and rectum.

This past colonoscopy I had in the beginning of 2018, showed chronic ileitis. My doctor didn't think much of it at the time and just dismissed it, until this last flare (I've had 3 this year). He thought maybe it was Crohns (he said that the inflammation in the Illieum isn't always Crohns and could be another process in my body going on). So, he did a IBD differentiation blood test on me. I was ASCA IGG positive, but ANCA negative. Unfortunately, he never followed up with my test results and because of his lack of quality care, I actually switched GI doctors (I have an appt with the new one in a couple of weeks). With my own research, the blood work seems to point to Crohns (I know it's not very reliable). I guess with the colonoscopy, my 3 flares this year (despite being on Pentasa) and the blood work it seems like it might be Crohns. I know that Crohns can also show up in the colon as well as the small intestine. So, back to my question, can they differentiate between UC and Crohns by a biospy? Or does it just show "inflammation". What led to the UC diagnosis this whole time as opposed to a Crohns? When I see my new doctor, what tests do you all recommend for determining what exactly I have? I'm just trying to get to the bottom of what EXACTLY I have.

TIA !

Biopsies often make it clear which it is, but sometimes even biopsies are indeterminate for whether you have Crohn's or ulcerative colitis.

There are features that make it pretty clear from biopsies that a person has Crohn's, but those features don't always show up. Sometimes it's hard to tell from the biopsies alone, so disease location also plays a role.

Can you get copies of pathology reports on your old colonoscopies? If not, you might have to have another at some point and wait for those biopsies.

In either case, it's pretty likely that Pentasa isn't enough for you.

It says you have inflammation in the ileum, known as ileitis, present within the mucosa (shallow tissue). The inflammation demonstrates both signs of acute (non-chronic) and chronic changes. When both acute and chronic are mentioned within the same biopsy sample, it always is the chronic part that sticks and is the most meaningful of the pair.

Unfortunately, some biopsy reports can be more detailed than others.

I'd assume you have UC unless something jumps out as being Crohn's disease. Like seeing aphthous ulcers (large, white canker sore-like ulcers within your intestine) would be a dead-giveaway of crohn's.

Exactly what you have may not matter all that much. Treating UC, Crohn's and a few of the varying shades of gray diagnosis's in-between (indeterminate-colitis, crohn's-colitis, etc) are all pretty much the same. Same meds, same screenings, same most everything (with the exception of surgeries).

iPoop - I wish it was more specific. When I had the colonoscopy at the beginning of the year, the doctor didn't think too much about it. However, after my 3 flares I've had this year and my symptoms (frequent bowel movements 10 a day, tenesmus, nausea, bloating, cramps, diarrhea) made him think that it might be Crohns. So, he sent me for a IBD differentiation panel and I was ASCA IGG positive and ANCA negative. I know it's not a definitive test, but it does suggest that I may have crohns.

I understand that they are treated similar, but for me, I really would like to know exactly what I have. So, I guess I will wait and suggest to my new GI doctor and I want another colonoscopy and other tests done.