IBD Unclassified

Key points 

  • Inflammatory bowel disease unclassified (IBDU) shares similarities with the two of the main types of IBD, Crohn’s disease and ulcerative colitis. 
  • People are diagnosed with IBDU when it isn’t clear if they have Crohn’s disease or ulcerative colitis. 
  • IBDU may lead to a diagnosis of Crohn’s disease or ulcerative colitis in the future. 

What is IBD unclassified? 

Crohn’s disease and ulcerative colitis are the two main types of inflammatory bowel disease (IBD) and because they share many similarities it can sometimes be difficult to tell the difference.  

Inflammatory bowel disease unclassified (IBDU), also known as indeterminate colitis (IC), is a type of IBD where it isn’t clear if it is Crohn’s or ulcerative colitis. This means signs of both diseases will appear in the gut. 

For example, inflammation caused by Crohn’s disease affects the full thickness of the gut while ulcerative colitis only affects the inner surface of the gut. In IBDU, this could mean that ulcers in the large intestine (a common sign of ulcerative colitis) affect the gut deeper than expected and there is no other sign that it’s Crohn’s. If there is a disease in the small intestine then it is usually considered to be Crohn’s disease.

IBDU can lean more towards either Crohn’s disease or ulcerative colitis. In the future, changes in the disease behaviour or appearance may result in a diagnosis of Crohn’s or ulcerative colitis. 

The uncertainty around IBDU can be frustrating so it’s important for you to be a strong advocate for your own healthcare and surround yourself with people who are supportive.  

For more information on IBD, see About Crohn’s disease or About ulcerative colitis

IBD Unclassified Symptoms 

Key points 

  • People with IBDU can experience symptoms differently from each other. 
  • Common symptoms of IBDU include abdominal pain and diarrhoea with blood. 
  • Gut inflammation can lead to symptoms that affect many different parts of your body so it can helpful to talk about them with your doctor. 

What are the symptoms of IBDU? 

Symptoms of IBDU can be different for each person and can be serious or mild. Symptoms will depend on where inflammation appears in your gut. 

The most common symptoms are: 

  • Abdominal pain 
  • Frequent diarrhoea (sometimes mixed with mucus and blood) and need to use the toilet 
  • Tiredness, fatigue 
  • Raised temperature, fever 
  • Loss of appetite, weight loss 
  • Anaemia (reduced level of blood cells) 

Inflammation in the gut can make it harder for the body to absorb nutrients from food, leading to many of these symptoms. 

Less common symptoms are: 

  • Joint pain 
  • Mouth ulcers (sores)
  • Eye inflammation (uveitis and episcleritis) 
  • Liver inflammation (Primary Sclerosing Cholangitis (PSC))
  • Skin rashes 

Always ask your doctor if you are worried about any of your symptoms. 

IBD Unclassified Diagnosis 

Key points 

  • IBDU is most commonly diagnosed in children. 
  • It is hard to diagnose someone with IBDU as the disease is still under discussion by health professionals. 
  • IBDU lies on a spectrum between Crohn’s disease and ulcerative colitis, sometime more like one than the other.  

How do I know if I have IBDU? 

There are no official diagnosis standards for IBDU yet and the disease classification is still being debated by health professionals. The unclear nature of IBDU can make it difficult in the diagnosis stage and when deciding on treatment. 

What is known is that IBDU is usually diagnosed in children and may settle into either Crohn’s or colitis as they grow older. Often the disease will have more features in common with either Crohn’s or ulcerative colitis. Some people will keep their IBDU diagnosis for the rest of their lives. 

To know if you have IBDU you will need to be tested by a doctor. Several tests will likely be needed before you can get a diagnosis. Tests may include: 

Blood tests: Used to find out if inflammation is present and if you have anaemia or low nutrition levels or signs of inflammation. 

Stool tests: Used to make sure your symptoms are not caused by an infection. Can also detect inflammation through a test for faecal calprotectin levels, which is a marker of white blood cells released from the inflammation of the gut lining. 

Endoscopy: Used to view the digestive system with an endoscope or tube with a camera and light at the end. Depending on the test, the camera may be inserted through the mouth or anus. A tissue sample (biopsy) may also be collected and examined. There are also endoscopic capsules that can be swallowed to capture images of the entire small bowel.

There are different types of endoscopies that may be used for ulcerative colitis. For example:

  • Upper GI endoscopy: The endoscope will enter your mouth or nose to examine your throat, stomach and the start of your small intestine.
  • Colonoscopy: Used to see the entire large intestine and the end of the small intestine and enters through the anus.
  • Sigmoidoscopy: Used to examine the rectum and lower part of the large intestine and enters through the anus.

Bowel imaging and scans: Used to discover inflammation and complications like strictures (narrowing of the gut), fistulae or abscesses. MRI (Magnetic Resonance Imaging) uses magnets and radio waves while CT (Computerised Tomography) scans use a series of quick x-rays to build a 3D image of the target area. Some centres may also use intestinal ultrasound. 

IBD Unclassified Treatment 

What kind of treatments are there for IBDU? 

There are not many clinical trials that focus on treating IBDU so in many cases the disease will be treated in a similar way to ulcerative colitis. Learn more about treating ulcerative colitis


The term indeterminate colitis (IC) was introduced by Ashley Price in 1978. In 2006 the IC term was replaced with inflammatory bowel disease unclassified (IBDU).  

Children are twice as likely to be diagnosed with IBDU compared to adults. 

80% of children who are diagnosed with IBDU later go on to be diagnosed with CD or UC. 

At the initial inflammatory bowel disease diagnosis, 10–15% of patients will be diagnosed as having indeterminate colitis.