Inflammatory Bowel Disease

Written by Abdul Wadood Mohamed and Elizabeth Boskey, PhD | Published on July 25, 2012
Medically Reviewed by George Krucik, MD


Inflammatory bowel disease (IBD) is not a single condition. It is the term for a group of disorders that cause prolonged inflammation of the digestive tract.

The digestive tract is composed of the mouth, esophagus, stomach, small intestine, and large intestine. It is responsible for breaking down food, extracting the nutrients, and removing any unusable material and waste products. Inflammation anywhere along the digestive tract disrupts this normal process. This can be very painful. In some cases, IBD can even be life threatening.

What Are the Main Types of Inflammatory Bowel Disease?

Many diseases are included in this umbrella term. The two most common are ulcerative colitis and Crohn’s disease. Crohn’s disease can cause inflammation in any part of the digestive tract. However, it mostly affects the tail end of the small intestine. Ulcerative colitis is inflammation of the large intestine. It gets its name because the colon is another name for the large intestine. The “itis” suffix means inflammation.

What Causes Inflammatory Bowel Disease?

IBD is a collection of several diseases. Therefore, it does not have a single cause. However, some IBD has been linked to heredity. It can also be caused by problems with the immune system.


If you have a sibling or parent with IBD, you are more likely to develop it yourself. Therefore, scientists think IBD may have a genetic component.

The Immune System

The immune system also plays a role in IBD. Normally, the immune system defends the body from pathogens. A bacterial or viral infection of the digestive tract can trigger an immune response. The digestive tract becomes inflamed as the body tries to fight off the invaders. When the infection is gone, the inflammation recedes. That’s a healthy response.

Some people with IBD experience digestive tract inflammation even when there is no infection. The immune system attacks the body’s own cells instead. This is known as an autoimmune response.

Another cause of IBD is inflammation not receding after an infection is cured. In people with IBD, such inflammation is prolonged. It may continue for months or years.

What Are the Risk Factors For Developing Inflammatory Bowel Disease?

The Centers for Disease Control and Prevention (CDC) estimates that 1.4 million people in the U.S. suffer from IBD. Environmental factors have a big impact on the development of Crohn’s disease and ulcerative colitis. Some other risk factors include:


Smoking is one of the biggest risk factors for developing Crohn’s disease. Smoking also aggravates pain and other symptoms and increases the risk of complications. However, ulcerative colitis primarily affects non-smokers and ex-smokers.


IBD occurs in all populations. However, certain ethnic groups such as Caucasians and Ashkenazi Jews have a higher risk.


In most cases, IBD starts before the age of 30. However, it can show up at any age.

Family History

People who have a parent, sibling, or child with IBD have a much higher risk of developing it themselves.

Geographical Region

People in urban areas and industrialized countries have a higher risk of IBD. So do those who work in white-collar jobs. This can partially be explained by lifestyle choices and diet. People who live in industrialized countries consume more fat and processed food. This may also explain the increase in IBD incidence from southern to northern latitudes.


Overall, IBD affects both genders equally. Ulcerative colitis is more common in men. Crohn’s disease is more common in women.

What Are the Symptoms of Inflammatory Bowel Disease?

Specific symptoms of IBD vary depending on the location and severity of any inflammation.

Diarrhea occurs when affected portions of the bowel can’t reabsorb water.

Bleeding ulcers may cause blood to show up in the stool. This is called hematochezia.

Inflammation can thicken the wall of the intestine and block the passage of fecal material. This can cause pain, cramping, and bloating.

Problems absorbing essential nutrients can lead to weight loss and anemia. They can also cause delayed growth or development in children.

People with Crohn’s disease may get canker sores in their mouths. Sometimes ulcers and fissures also appear around the genital area or anus.

Finally, IBD can be associated with problems outside the digestive system, such as:

  • eye inflammation
  • skin disorders
  • arthritis

What Are the Possible Complications from Inflammatory Bowel Disease?

Possible complications of IBD include:

  • malnutrition
  • colon cancer
  • fistulas – a fistula is an ulcer that goes through the bowel wall, creating a hole between different parts of the digestive tract
  • intestinal rupture
  • bowel obstruction

In rare cases, a severe bout of IBD can put you into shock. This can be life threatening. Shock is usually caused by blood loss during a sudden and prolonged episode of bloody diarrhea.

How Is Inflammatory Bowel Disease Diagnosed?

The first step in diagnosing IBD is a thorough medical history. This will include questions about family history as well as information about bowel habits. A physical exam may then be followed by one or more diagnostic tests.  

Stool Sample and Blood Tests

These tests can be used to look for infections and other diseases. Blood tests can also sometimes be used to distinguish between Crohn’s disease and ulcerative colitis. However, blood tests alone cannot be used to diagnose IBD.

Barium Enema

Barium enemas are used to make the colon and small intestine visible by X-ray. Although they used to be done frequently, other tests have largely replaced them.

Flexible Sigmoidoscopy and Colonoscopy

These procedures use a camera on the end of a thin, flexible probe to look at the colon. The camera is inserted through the anus. It allows your doctor to look for ulcers, fistulas, and other damage. Colonoscopy can examine the entire length of the large intestine. Sigmoidoscopy examines only its last third, the sigmoid colon.

Sometimes during these tests a small sample of bowel wall will be taken. This is called a biopsy. Examining this biopsy under the microscope can be used diagnose IBD.

Capsule Endoscopy

The small intestine is much harder to examine than the large intestine. For this test, you swallow a small capsule containing a camera. As it moves through your intestine, it takes pictures. Once you have passed the camera in your stool, the pictures can be seen on a computer.

This test is only used when other tests have failed to find the cause of Crohn’s disease symptoms.

Plain Film or X-Ray

A plain abdominal X-ray is useful in emergency situations when intestine rupture is suspected.

Computer Tomography (CT) and Magnetic Resonance Imaging (MRI)

CT scans are basically computerized X-rays. They create a more detailed image than a standard X-ray. This makes them useful for examining the small intestine. They can also detect complications of IBD.

MRIs use magnetic fields to form images of the body. They are safer than x-rays. MRIs are good for examining soft tissues. They are especially useful in detecting fistulas.

Both MRIs and CT scans can be used to determine how much of the intestine is affected by IBD.

How Is Inflammatory Bowel Disease Treated?

There are a number of different treatments that can be used for IBD.

Anti-inflammatory drugs are the first step in IBD treatment. These drugs decrease inflammation of the digestive tract. However, they have many side effects. Anti-inflammatory drugs used for IBD include sulfasalazine and its derivatives and corticosteroids.

Immune suppressants prevent the immune system from attacking the bowel and causing inflammation. This group includes drugs that block TNF. TNF normally modulates inflammatory activity in the body. These drugs also have many side effects.

Antibiotics are used to kill bacteria that may trigger or aggravate IBD symptoms.

Anti-diarrheal drugs and laxatives can be used to treat IBD symptoms.

Lifestyle choices are important when you have IBD. Drinking plenty of fluids helps to compensate for those lost in stool. Avoiding dairy products and stressful situations also improves symptoms. Exercise can help improve your health, as can stopping smoking.

Vitamin and mineral supplements can help with nutritional deficiencies. For example, iron supplements can treat anemia.

Surgery can sometimes be necessary for people with IBD. Some IBD surgeries include:

  • strictureplasty to widen narrowed bowel
  • surgery to close or remove fistulas
  • removal of affected portions of the intestines, for people with Crohn’s disease
  • removal of the entire colon and rectum, for severe cases of ulcerative colitis

Routine colonoscopy is used to monitor your increased risk for colon cancer.

How Can Inflammatory Bowel Disease Be Prevented?

The hereditary causes of IBD cannot be prevented. However, you may be able reduce your risk of IBD, or prevent a relapse, by:

  • eating a healthy diet
  • exercising regularly
  • quitting smoking

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