What Is Terminal Ileitis?

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Terminal ileitis is the inflammation of the terminal end of the ileum, which is the last section of the small intestine before it leads into the large intestine. This inflammation affects the health of the gastrointestinal (GI) system, which, in turn, may show up as GI symptoms, such as abdominal pain and cramping or diarrhea. 

Terminal ileitis is often associated with Crohn’s disease, a form of inflammatory bowel disease, but that is not always the case. Because terminal ileitis can be caused by multiple conditions, understanding the underlying cause is crucial to getting the right treatment.

This article will discuss the symptoms, diagnostic tests, and treatment options for terminal ileitis.

Woman holding stomach in pain

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Terminal Ileitis Symptoms

Because several conditions can cause inflammation of the ileum, symptoms of terminal ileitis vary. Generally speaking, symptoms of ileitis include: 

  • Lower abdominal pain and cramps
  • Diarrhea
  • Bloody diarrhea

It’s important to keep in mind that symptoms like cramping and diarrhea can happen in everyday life for a variety of reasons. However, chronic inflammation of the ileum might cause these symptoms to linger. It is best to speak to a medical professional about these symptoms if they persist so that they can help you get to the bottom of what’s causing them. 

In some cases, terminal ileitis presents without any symptoms. The condition might only be discovered incidentally during a routine colonoscopy—a procedure where a scope with a camera on the end is guided through the colon to check for abnormalities.

Guidance on the management of terminal ileitis without symptoms varies. Research suggests that if there are no digestive symptoms or history of Crohn’s disease with a case of terminal ileitis, the risk of developing Crohn’s is rare, and further testing or treatment may not be recommended.


Although ileitis is commonly associated with Crohn’s disease—a chronic digestive disease cause by inflammation of the colon—there are many other conditions that affect the ileum. Some other conditions that can cause inflammation of the terminal ileum include ulcerative colitis, intestinal infections, lymphoma, lymphoid hyperplasia, and nonsteroidal anti-inflammatory drug (NSAID) use.

When looking at ileitis on its own, there is evidence that it shares some of the same genetic (NOD2) mutations as Crohn’s disease. Besides a genetic component, inflammation could result from physical damage to the lining of the ileum.

Some cases of terminal ileitis may be due to lesions on the ileum. For example, terminal ileitis may show up as small ulcers on the ileum, though it is rare and will often just show up as non-specific inflammation.

As the causes of terminal ileitis vary quite a bit, medical help is critical to get to the root cause of terminal ileitis so that the right diagnosis is reached.


Terminal ileitis on its own (also known as isolated acute terminal ileitis) is difficult to diagnose because it doesn’t have the same chronic characteristics of inflammatory bowel disease. It also can be caused by a multitude of things, including something as common as NSAID use.

Furthermore, other pathological conditions such as Crohn’s disease can look like terminal ileitis. Thus, it may be misdiagnosed as Crohn’s. 

Terminal Ilietus and Crohn’s Disease

Researchers have looked closely at the connection between terminal ileitis and Crohn’s disease and found limited evidence that terminal ileitis leads to Crohn’s. One group of researchers examined the progression between the two conditions and found that terminal ileitis without a history of inflammatory bowel disease rarely progresses to Crohn’s disease, with only 5% of their cases doing so.

However, there may be some indicators specific to terminal ileitis-related Crohn’s disease. For instance, research suggests that narrowing of the bowel wall, as seen on abdominal imaging, may be indicative of terminal ileitis that will progress to Crohn’s disease.

Knowing the difficulty in diagnosing terminal ileitis, a complete diagnostic workup is often recommended to try and get to the right diagnosis. Your doctor will likely recommend a colonoscopy with an ileoscopy.

A colonoscopy is a procedure where a thin scope with a camera on the end is threaded through the colon to look for abnormalities. During the ileoscopy, the scope is guided into the small intestine to look specifically at the ileum.

In some cases, your doctor may take a biopsy (a small tissue sample) of the terminal ileum during the colonoscopy and ileoscopy to be sent back to the lab and examined under a microscope. This can help your doctor make a definitive diagnosis.


Treatment for terminal ileitis depends on its cause. For example, if terminal ileitis is the result of Crohn’s disease, treatment for Crohn’s disease will follow.

Some cases of terminal ileitis may not be harmful, as is sometimes the case with asymptomatic terminal ileitis, and therefore no further workup or treatment may be needed.

These different pathways highlight the importance of getting the right diagnosis. Knowing the root problem is key to knowing how to proceed with treatment.

A Word From Verywell

Terminal ileitis has its fair share of nuances, making it a difficult condition to diagnose. Because it is commonly associated with Crohn’s disease but can be caused by various other conditions of the gastrointestinal system, getting a diagnosis from a medical professional is crucial to moving forward with the best treatment plan for your situation.

Though it is common to have gastrointestinal symptoms such as diarrhea and abdominal cramping from something minor, if these symptoms become chronic, or if you see blood in your stool, it is best to talk to your doctor. It may be a process as you get to the root cause of the issue, but being able to address the cause will get you on the path to feeling better. 

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Bojic D, Markovic S. Terminal ileitis is not always Crohn’s diseaseAnn Gastroenterol. 2011;24(4):271-275.

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  5. Tse CS, Deepak P, Smyrk TC, Raffals LE. Isolated acute terminal ileitis without preexisting inflammatory bowel disease rarely progresses to Crohn’s diseaseDig Dis Sci. 2017;62(12):3557-3562. doi:10.1007/s10620-017-4803-8

By Emily Brown, MPH
Emily is a health communication consultant, writer, and editor at EVR Creative, specializing in public health research and health promotion. With a scientific background and a passion for creative writing, her work illustrates the value of evidence-based information and creativity in advancing public health.