What is Indeterminate Colitis?

B.S. Dietetics, Dietitian, Health Professional

In adult and childhood inflammatory bowel disease (IBD), the diagnosis is usually classified between Crohn's disease and Ulcerative Colitis (UC).   However, for 10 percent of IBD patients they do not fall into either of those categories and end up being classified as Indeterminate Colitis (IC).   This diagnosis can also be given in patients who can not be given a clear diagnosis of UC or Crohn's through standard testing, such as imaging, labs, biopsy or colonoscopy.

Some research shows that there are people who progress from the Indeterminate Colitis diagnosis into one of the classic categories but there are many who do not, which indicates that IC is likely a diagnosis of its own.   When this becomes most important is when we talk about treatments beyond the pharmacological ones.

Surgical treatment

In patients with Ulcerative Colitis the standard surgical treatment is a total proctocolectomy with ileal pouch anal anastomosis (IPAA).   Crohn's patients usually do not do well with a IPAA due to a higher risk of complications following surgery and the potential for disease formation in the pouch leading to subsequent pouch removal.   As one might expect, patients with Indeterminate Colitis fare somewhere in between the two other categories: some patients doing well with surgery and some not as well.     These risk factors are very important for IC patients to discuss with their physicians and surgeons.


There is currently no clear diagnostic test for IC and it is often diagnosed by excluding the other two disease categories.   Some research is being done looking at serological markers that are not present in UC or Crohn's.   This can be helpful, but because these markers are also not present in healthy individuals, it is still somewhat of a process of elimination.   Biomarkers are also being looked into for distinguishing between Crohn's and IC.   In Crohn's patients, up to 80 percent may test positive for a specific biomarker, but that still leaves 20 percent that are still not accounted for, again making the testing a process of elimination.

The next step is the need for a definitive diagnostic test for IC.   Research into treatments specific to IC can not begin until there is a definitive test.   If your doctor has diagnosed you with IC, be sure to discuss with them how this diagnosis changes your treatment plan.   Should you have to go to surgical interventions, weigh the risk vs. benefit with extra caution and get all of the facts first.