CT Scan

What is a CT Scan?

While MRI (magnetic resonance imaging) is more popular in Europe and other Western countries, CT scan (computed tomography or CAT scan) is probably the most commonly ordered medical imaging test in the United States. CT scan is a minimally invasive, quick and painless method of diagnosis, although there are, of course, limitations to how much detail a doctor will be able to get without traditional endoscopy. If abnormal growths like cancer or polyps are found, a more thorough procedure may need to be performed in order to further test it, or remove it altogether.

CT scanning uses x-ray to capture cross-sectional, “slice” images of a person’s inner organs, and then puts a series of pictures together in order to form a digitized, 3D view that is supposed to replicate what the organ looks like had open surgery or a more invasive technique been used. A patient is usually asked to lie perfectly still on a moveable examination table that goes through a cylinder-shaped machine that performs the scan. The procedure only takes a couple of minutes. Before going into the machine, sometimes a patient will be asked to drink special contrast solutions that make their inner organs show up brighter on the final x-ray and give doctors a clearer view. Depending on the area being examined, a special solution may also be injected through an intravenous line (IV).

While CT scanning is often used to scan bone structures, such as the skull or the spine, a gastroenterologist would order a CT scan to examine the chest and abdominal areas for problems relating to the body’s digestive system. Common gastroenterological (GI) organs scanned by CT include the kidneys, the liver, the pancreas, the gallbladder, the spleen, the aorta, the ovaries, the uterus and the large and small intestines.

Do I Need to Do Anything Before Getting a CT Scan?

When the GI tract is being scanned by CT, patients usually are asked to avoid eating for 8 to 12 hours before the procedure. Any food remaining in the body can be mistaken for a growth and can mislead the doctor.

Are There Any Risks Associated with a CT Scan?

In general, CT scans are very safe and have few risks associated with them. The amount of radiation the patient Is exposed to during the procedure is quite small, and has not been reported to cause any problems in male patients, and female patients who are not pregnant.  There are some concerns due to life-long quantities of radiation applied to patients, these risks should be discussed with your doctor – especially if you have required CT scans in the past.  There are small risks of allergic reaction to the IV contrast sometimes used; this is especially common in patients who have history of iodine allergies and should be discussed before proceding with this procedure.

If there are any complaints, it usually has to do with the solution the IV solution required for scanning of the kidneys and certain blood vessels. Common symptoms include itchiness, rashes or hives that go away within a few days. Rarely, in more serious cases, a patient may have an anaphylactic reaction with causes them to break out in hives and have trouble breathing. If you have diabetes or severe dehydration, you also have a chance of kidney failure—although this is even rarer of an occurrence. Discuss with your doctor if you are concerned about a bad reactions to medication given to you before a CT scan.


Reviewed 12/29/2011 by David M. Nolan, M.D.
Diplomate of the American Board of Internal Medicine, 2011
Currently a Fellow of Gastroenterology, at UCI 2011-2014