Imaging Tests for IBS

Reviewed by: HU Medical Review Board | Last reviewed: May 2023

To reach an irritable bowel syndrome (IBS) diagnosis, doctors may use several tests. These may include imaging tests if other tests, like blood or breath tests, do not provide answers. The imaging tests doctors use are often based on a person’s symptom history and personal medical history.1

Examples of imaging tests for IBS include a lower gastrointestinal (GI) series and a computed tomography (CT) scan. While they cannot confirm an IBS diagnosis, imaging tests can help rule out other conditions.1

Lower GI series

A lower GI series, also called a barium enema, is an X-ray exam that focuses on the large intestine. It is used to diagnose a number of conditions that affect the large intestine.2

If you go to your doctor complaining of abdominal pain, chronic diarrhea, constipation, or unexplained weight loss, a lower GI series may be used to find the cause. If you notice any bleeding from your anus, your doctor may use a lower GI series to assess the presence of hemorrhoids or another issue.2

What is involved in a lower GI series?

Before you have a lower GI series, your colon must be completely cleaned out. This is to make sure the X-ray gets accurate results. You will receive instructions on how to cleanse your colon in the day(s) leading up to the procedure.2

This cleansing process requires drinking a bowel prep drink at home that cleans out your bowels. You also must be on a clear liquid diet for about 1 to 3 days before the test.2

During the procedure, a radiologist inserts a small tube into the rectum and injects a liquid that contains barium. Barium is a contrast material that helps to highlight the colon on X-rays. You may be asked to change positions during the procedure, which can help the technician view different parts of your colon.2

The X-ray images produced by this test can help find any abnormalities in the colon that may be causing GI symptoms, such as:2

  • Cancerous growths (colon cancer)
  • Inflammation causing small pouches in the colon (diverticulitis)
  • An abnormal tunnel between two organs in the body, often found in the areas around the rectum and anus (fistula)
  • Inflammation of the intestinal lining, which indicates ulcerative colitis or Crohn’s disease
  • Small growths in the lining of the intestines (polyps)
  • Sores on the intestinal lining (ulcers)
  • Blockages of the large intestine (obstructions)

For someone with IBS, the results of a lower GI series will come back normal. IBS is a functional gut disorder, meaning it does not cause any physical damage to the GI tract. So, there would be no visible intestinal damage on an X-ray.3

Computed tomography (CT) scan

CT scans offer a more detailed view of the entire GI tract. A CT scan uses special X-rays and computer technology to produce cross-sectional images of the inside of the body. A CT scan can help find problems in the digestive system such as inflammation and tumors.1,4

Doctors usually use CT scans for IBS only in cases where a lower GI series has not provided enough information or when they suspect symptoms are caused by a different medical issue. These issues may include:1,4

  • Diverticulitis
  • Crohn's disease
  • Colon cancer
  • Blood clots
  • Internal bleeding

What is involved in a CT scan?

During a CT scan, you will lie still on a table while the table passes through the center of a large X-ray machine. A CT scan is much less invasive than a lower GI series. It is a painless procedure and is generally considered safe.4

However, a CT scan exposes you to a larger amount of radiation than X-rays. Discuss any concerns about radiation exposure with your doctor.3

Other tests for IBS

Imaging tests are just 1 of many tests used to help with an IBS diagnosis. Other tests that are used to help diagnose IBS include:1

  • Physical exam
  • Medical and symptom history
  • Stool analysis
  • Blood tests
  • Breath tests
  • Sigmoidoscopy or colonoscopy

Imaging tests are not always necessary or right for every person. The decision to use them should be based on your individual case. Ask your doctor which imaging tests, if any, they recommend.

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