Abdominal Computed Tomography (CT) Scan

While not commonly used for IBD, this test is very specific

CT Scan
A healthcare worker looks at a computer image while a patient lies in an imaging machine. Photo © National Institute of Diabetes and Digestive and Kidney Diseases, NIH

A computed tomography (CT) scan (also sometimes called a computerized tomography scan) is a type of x-ray that provides a cross-sectional view of the body. The images obtained during a CT scan show the organs and tissues inside the body. The output of a CT scan is electronic, and therefore can be displayed on a computer, emailed, or transferred to a CD or a mobile device. A CT scan is a painless and non-invasive procedure. A CT scan will not necessarily detect the presence of inflammatory bowel disease (IBD) but it may be used as part of a more comprehensive workup to diagnose Crohn's disease or ulcerative colitis.


The images from a CT scan can be used for a wide variety of purposes in diagnosing and monitoring diseases and conditions. In cases where a patient is experiencing abdominal pain or has a digestive disease, a CT scan may be used for diagnosing and monitoring:

CT scans are also used to aid physicians in taking biopsies, because the internal organ structure can be seen and used much like a map, and performing or monitoring the results of other surgical procedures.


In general, there is no special preparation needed for a CT scan other than fasting for a few hours before the test. Similar to a regular x-ray, patients are asked to remove any jewelry or other metal items, such as eyeglasses. Patients may also be asked to remove medical devices such as dentures and hearing aids.

How the Test Is Performed

Patients are asked to lie on a table, either flat with arms at sides or with arms up and lying next to the head. The table will slide into the center of a large, spherical x-ray machine. This machine will rotate around the patient during the test. While inside the machine, there may be whirring or mechanical noises.  In some cases, patients may be given a pair of earplugs or headphones to wear. For longer tests, music might be played through headphones to make a patient feel more comfortable.

Patients are asked to lie very still during the test, and asked to hold their breath at certain points during the test. The test can take anywhere from 15 minutes to one hour, depending on the parts of the body being pictured and how many images are needed. Most tests are completed in about half an hour.

In some cases, contrast dye may be given. Contrast dye will help certain body structures to show up more clearly in the final images from the scan. The contrast dye might be drunk, injected into a vein, or given as an enema.


A CT scan will expose a patient to a certain amount of radiation, which is more radiation than a typical flat x-ray. The risks associated with the amount of radiation exposure should be carefully weighed against the benefits of having the test.

Rarely, a patient may have an allergic reaction to the contrast dye. This allergic reaction could cause symptoms of nausea, vomiting, hives, itching, trouble breathing or swelling. If you experience these or any other symptoms during or after a CT scan, you should notify the radiology technician and/or your physician. If you have a known allergy to contrast material, you may be given some antihistamine medication to reduce the chance of an allergic reaction.

Women who may be pregnant should inform the radiology technician and their physician. In general, CT scans are not recommended during pregnancy except in certain circumstances.

Follow Up

Your physician will review the images from the CT scan with you and discuss any further testing that may be needed.

A Note From Verywell

CT scans are sometimes used for the management of IBD. However, it's important that this test is only done when clearly needed. In some cases, there may be other tests that can provide similar, or improved, information, yet are associated with less radiation exposure. Understanding why a test is being ordered, as well as letting any healthcare professionals know when and how many CT scans have been done in the past, is and important part of advocating for oneself in the healthcare environment.

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