Also Known As
IBD
Crohn Disease
Ulcerative Colitis
This article was last reviewed on
This article waslast modified on
November 28, 2017.
What is inflammatory bowel disease?

Inflammatory bowel disease (IBD) is a group of chronic disorders characterized by swollen and damaged tissues in the digestive tract. These conditions vary in severity from person to person and change over time. Periods of active disease may alternate with periods of remission. During a flare-up, a person may experience frequent bouts of watery and/or bloody diarrhea, abdominal pain, weight loss, and fever. Symptoms frequently diminish between these flare-ups. Many people may go through extended periods of remission between flare-ups. 

IBD affects one to three million people in the United States, according to the Centers for Disease Control and Prevention. The cause is not known, but some evidence points to a complex interaction of different factors, including a genetic predisposition and the presence of microbes in the digestive tract that trigger an abnormal immune response.

The most common inflammatory bowel diseases are Crohn disease (CD) and ulcerative colitis (UC). IBD affects both sexes, though UC is slightly more common in men and Crohn disease is more common in women. Both are most common in Caucasians and people of Ashkenazi Jewish origin who live in developed countries. However, IBD is increasing among non-Caucasians in North America.

Either form of IBD may affect anyone at any age, but the majority of cases are first diagnosed in people 14 to 24 years old, while a smaller number of cases are diagnosed between the ages of 50 and 70. In addition to gastrointestinal symptoms, children affected by CD or UC may experience delayed development and growth retardation. Those who are diagnosed with one of these conditions at a young age are also at an increased risk of developing colon cancer later in life.

Accordion Title
About Inflammatory Bowel Disease
  • Crohn Disease (CD)

    Crohn disease can affect any part of the digestive tract from the mouth to the anus but is primarily found in the last part of the small intestine (the ileum) and/or in the colon (large intestine or bowel). With CD, bowel tissue may be affected in patches with normal tissue in between. Inflammation may penetrate deep into the tissues of the intestines/colon and form ulcers or fistulas. Fistulas are tunnels through the intestines that allow waste material to move into other areas. Other complications of CD may include bowel obstructions, anemia from bleeding tissues, tears in the anal skin, and infections. According to the Crohn's & Colitis Foundation of America, about two-thirds to three-quarters of people with Crohn disease will eventually require surgery, either to remove damaged sections of the intestines/colon or to treat an obstruction or fistula.

  • Ulcerative Colitis (UC)

    Ulcerative colitis primarily affects the surface lining of the colon. Although the symptoms may be similar to those seen with CD, the tissue inflammation caused by UC is continuous rather than patchy. The inflammation usually starts from the anus and moves up the colon. Bloody diarrhea is more frequently seen with UC. The most serious complication of UC is toxic megacolon, a relatively rare acute condition in which a section of the colon becomes essentially paralyzed. Waste does not move through the section; it accumulates and dilates the colon. This can cause abdominal pain, fever, and weakness. It can become life-threatening if left untreated. People with toxic megacolon may need surgery to remove the large intestine.

  • Signs and Symptoms

    Signs and symptoms of the two common forms of inflammatory bowel disease, Crohn disease and ulcerative colitis, are similar and overlap, often making it difficult to distinguish between the two. Symptoms usually develop gradually over time but sometimes may appear suddenly and without notice. There may be times when the disease is active (flares), when symptoms are most noticeable, and periods of remission, when signs and symptoms subside, sometimes for months or years at a time.

    While signs and symptoms vary in severity and differ from person to person, the most common ones include:

    • Abdominal cramps and pain
    • Persistent diarrhea
    • Bleeding from the rectum (blood in the stool)
    • Loss of appetite and unexplained weight loss


    Less common signs and symptoms may include:

    • Fever
    • Fatigue
    • Anemia
    • Joint pain
    • Skin rashes
    • In children and youth, failure to thrive and delayed growth
  • Tests

    Before any diagnostic tests are done, a healthcare practitioner will gather information on a person's medical and family history as well as signs and symptoms, including the frequency and/or duration of diarrhea. The healthcare practitioner will be considering things that are out of the ordinary and that might be associated with conditions that cause diarrhea and other symptoms. A series of questions may be asked to help make informed choices about which tests will be helpful in establishing a diagnosis.

    Laboratory Tests
    There is no single laboratory test that can definitively diagnose inflammatory bowel disease (IBD). However, laboratory testing is an important tool for evaluating a person who may have IBD. If a person has persistent diarrhea and abdominal pain, an initial set of tests are done to help evaluate the person's condition. These may be done in conjunction with imaging tests, such as an X-ray or CT scan.

    Examples of some common initial tests include:


    At the same time or in follow up, a healthcare practitioner may order several tests to rule out other causes of diarrhea, abdominal pain, and colitis. Other possible causes include viral or bacterial infections, parasites, colon cancer, and other chronic conditions such as celiac disease. Some examples of tests that may be done to help rule out these other conditions include:


    If it is suspected that the person is unable to digest or absorb nutrients properly (malabsorption), then tests may be done to detect nutritional deficiencies. Examples include:


    As infections and other causes such as celiac disease are ruled out, other laboratory tests may be done to help pinpoint a cause:

    • Stool WBC to detect white blood cells in the stool, an indication of inflammation in the digestive tract; only certain diseases result in the presence of WBCs in the stool, so this test may help narrow the possibilities.
    • Calprotectin and lactoferrin are two stool (fecal) tests that detect substances released by white blood cells. These substances are associated with inflammation and with disease activity, severity, and relapse. They may be used to help distinguish between IBD and non-inflammatory disorders and also to monitor IBD. These tests are more sensitive than the test for stool WBC.

    If initial tests rule out other causes and it is suspected that a person has IBD, then a healthcare practitioner may order tests that detect antibodies frequently present in the blood of people who have IBD. One or more of these may be ordered to help distinguish between the two most common types of IBD, ulcerative colitis (UC) and Crohn disease (CD). There is some overlap in the presence of these antibodies in UC and CD, and they are not sensitive or specific enough to diagnose either condition, but they may give the healthcare practitioner additional useful information.

    Examples of antibody tests that may be done include:

    • pANCA (Perinuclear anti-neutrophil cytoplasmic antibody). More common with UC, it is found in about 60% to 80% of people with UC but only about 5% to 15% of people with CD.
    • ASCA (Saccharomyces cerevisiae antibodies), IgG and IgA. ASCA is more common with CD. ASCA IgG is found in about 60% to 70% of people with CD and in 10% to 15% of people with UC. ASCA IgA is found in about 35% of people with CD and less than 1% of those with UC.
    • Anti-CBir1 (Clostridium species antibodies). Found to in about 55% of people with CD and 10% of people with UC.
    • Anti-Omp C (Escherichia coli antibodies). Associated with rapidly progressing Crohn disease and found in 55% of people with CD and 5% to 10% of people with UC.
    • Anti-I-2 (Pseudomonas fluorescens antibodies) This is positive in 55% of CD cases and 10% of UC cases.


    Ultimately, a biopsy may be done to establish a diagnosis of IBD. A biopsy is considered the gold standard for the diagnosis of inflammatory bowel disease (and for distinguishing between ulcerative colitis and Crohn disease. A sample of tissue is obtained from the digestive tract during endoscopy or colonoscopy (see below). The tissue is evaluated by a pathologist for inflammation and abnormal changes in cell structures that are characteristic for each type of IBD. (For more about biopsies, read Anatomic Pathology.)

    Non-laboratory Tests
    One or more imaging tests may be done at the same time as laboratory testing to help diagnose and/or monitor UC and CD. Typically, the less invasive ones, such as an X-ray, are done earlier in the diagnostic process, while more invasive tests such as colonoscopy are done only as necessary and when a diagnosis is difficult. These imaging tests can be used to look for characteristic changes in the structure and tissues of the intestinal tract and to detect blockages.

    • X-ray (abdominal). This may be one of the initial imaging test done to view the digestive tract.
    • Computed tomography (CT). Also may be done early in the process to view the digestive tract; these typically provide greater detail than a standard X-ray.
    • X-ray with barium. Barium contrast dye allows an evaluation of the intestines. This is more commonly used in severe IBD to rule out serious complications like a perforated colon.
    • Sigmoidoscopy. A slender tube is used to examine the last 2 feet of the colon.
    • Colonoscopy. A slender tube is used to examine the entire colon; it includes a light and camera and can be used to take biopsies.
  • Treatment

    Treatment of inflammatory bowel disease (IBD) is targeted at reducing inflammation, relieving symptoms such as pain and diarrhea, controlling and healing damage where possible, identifying and addressing complications, and supplementing any nutritional shortages. The needs of someone with IBD will vary and frequently change over time.

    People with ulcerative colitis or Crohn disease need to be regularly monitored and should work with their healthcare practitioners to become educated about their condition. While lifestyle changes, such as diet modification, rest, and stress reduction, may help improve a person's quality of life and extend a remission, they cannot prevent an IBD flare-up.

    Acute symptoms are treated with a variety of medications. These drugs are effective, but many can only be given for short periods of time because of their side effects. Current therapies include the use of corticosteroids, anti-inflammatories, immunosuppressant drugs, biologic therapies (drugs that target body chemicals that cause tissue damage, such as tumor necrosis factor alpha [TNF-alpha]), and probiotics (so-called "good" bacteria that may improve the balance of bacteria in the digestive system).

    One or more surgeries may eventually be necessary to remove damaged tissue, to treat fistulas, and to relieve obstructions. In a person who has had UC for some time, surgery to remove all or part of the colon (colectomy) may be done to prevent colon cancer, if there are abnormalities seen on a biopsy.

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