Indeterminate Colitis

When an individual is suspected of having IBD, there are times it may be hard for the physician pinpoint their exact diagnosis. The term indeterminate colitis has been developed to categorize individuals with current symptoms and diagnostic test results that show inflammatory bowel disease, but do not definitively place them into a concrete IBD category such as ulcerative colitis or Crohn’s disease.^1,2

What is indeterminate colitis?

In approximately 10-15% of all IBD cases, the diagnostic test results and symptom presentation will make it difficult to make the distinction between Crohn’s disease and ulcerative colitis.^3,4 When this happens, the individual is diagnosed with indeterminate colitis. Studies show that between 50-80% of individuals diagnosed with indeterminate colitis will at some point be given a distinctive diagnosis of either ulcerative colitis or Crohn’s disease.^3,5

When and how is indeterminate colitis diagnosed?

Indeterminate colitis is not a positive diagnosis, but rather is a diagnosis based on exclusion of other conditions. Essentially, an individual is diagnosed with indeterminate colitis because they have symptoms of inflammatory bowel disease, but the medical team is unable to determine if they have ulcerative colitis or Crohn’s disease. The same diagnostic procedures used to diagnose all forms of IBD, including a scope of the digestive tract (upper endoscopy or colonoscopy), biopsy, MRI, CT scan, or ultrasound may be used, but the diagnosis is only given after the other possibilities are rejected.^2,3,6 Even though many patients do ultimately receive a different diagnosis of Crohn’s disease or ulcerative colitis, the number of individuals who remain with this diagnosis have lead some to propose that indeterminate colitis be considered its own condition. However, future research needs to be done in order to strengthen this idea.

What causes indeterminate colitis?

Just as the causes of IBD are unknown, so are the causes of indeterminate colitis. Many experts agree that a complex interaction between genetics, the bacterial composition of the digestive tract, environmental factors, and the immune system can lead to IBD. More specifically, it is often thought that the inflammation is due directly to the body’s immune system mistakenly attacking itself and the cells that line the gastrointestinal tract.^1,7

In regards to indeterminate colitis specifically, we know there are some instances where an individual may actually have ulcerative colitis or Crohn’s disease, but are instead diagnosed with indeterminate colitis. Reasons for this misdiagnosis may include inadequate diagnostic examination methods being used, a less-experienced healthcare team performing diagnostic exams, having very early stages of IBD that may not be progressed enough to be distinguishable, or receiving diagnostic tests during certain times, such as during periods of refractory (or unmanageable) IBD that may lead to indistinguishable tissue.^2,4

What are the symptoms of indeterminate colitis?

The symptoms of indeterminate colitis are similar to the symptoms of IBD and include, but are not limited to:

• Abdominal pain and cramping
• Persistent diarrhea
• Blood in the stool
• Bleeding from the rectum
• Unexpected or unintended weight loss
• Reduced appetite
• Fever
• Fatigue
• Changes in bowel movement patterns, such as an urgent need to evacuate or a feeling of incomplete evacuation¹

What are the treatment options for indeterminate colitis?

The treatment options for indeterminate colitis are similar to IBD and include, but are not limited to:

• Biologic therapy
• Corticosteroids
• Anti-inflammatory medications
• Immune system-suppressing medications
• Antibiotics
• Surgery (in some cases)^1,2

It is important to note however, that some treatment options, including both certain medications and some surgical procedures, are condition-specific, meaning they may only be beneficial for one type of IBD, and may actually be harmful for individuals with another type of IBD. For example, if your indeterminate colitis will eventually be diagnosed as Crohn’s disease, but you had a surgical procedure that is beneficial for someone with ulcerative colitis and risky for someone with Crohn’s disease, you may experience complications later on.² This is why it is important for your healthcare team to thoroughly investigate your symptoms and disease progression to make sure that a positive diagnosis is not possible before proceeding with treatment.