A computed tomography (CT) scan is an imaging test that uses X-rays and a computer to make detailed images of the body. A CT scan shows details of the bones, muscles, fat, soft tissues, organs, and blood vessels. They are more detailed than regular X-rays.

In a CT scan, an X-ray beam moves in a circle around your body. This allows many different views of the same part of the body. The X-ray information is sent to a computer that interprets the X-ray data and displays it on a monitor.

During some tests, you receive a contrast dye. This can be given orally, though a vein, or both ways. It makes parts of your body show up better in the image.

CT scans of the abdomen can give more detailed information than regular X-rays. CT scans can give doctors more information about injuries or diseases of the abdominal organs.

The abdomen contains many organs. These include the gastrointestinal, urinary, endocrine, and reproductive systems. A CT scan of the abdomen may be used to check the abdomen and its organs for:

• Tumors or other lesions
• Injuries
• Bleeding
• Infections
• Blood vessel problems
• Unexplained belly pain
• Blockages
• Other health problems

A CT scan may be done when another type of exam, such as an X-ray or physical exam, is not conclusive.

It may also be used to check tumors and other conditions of the abdomen before and after treatment. Or it can be done to guide the needle during biopsies and other procedures. A biopsy is when a small piece of tissue is removed so it can be examined in the lab.

There may be other reasons you need a CT scan of the abdomen. Check with your doctor for more information.

You may want to ask your doctor about the amount of radiation used during the CT scan. They can also explain your personal risks. CT scan radiation varies depending on the region of the body being examined, but it may be 100 to 800 times greater than a regular chest X-ray. It is a good idea to keep a record of your radiation exposure, such as previous CT scans and other types of X-rays, so that you can inform your doctor. Risks linked to radiation exposure may be related to the cumulative number of X-ray exams or treatments over a long period.

If you are pregnant or think you may be pregnant, tell your doctor. Radiation exposure during pregnancy may lead to birth defects.

If contrast dye is used, there is a risk for allergic reaction to the dye. If you are allergic to or sensitive to medicines, contrast, or iodine, tell your doctor.

Nursing parents should talk with the radiologist about when to resume breastfeeding after the contrast material is injected.

Tell your doctor if you are taking the diabetes medicine metformin. You may be told to stop taking this medicine before the scan.

People with kidney failure or other kidney problems should talk with their doctor. In some cases, the contrast dye can cause kidney failure. People with kidney disease are more prone to kidney damage after contrast exposure.

There may be other risks depending on your specific medical problems. Be sure to discuss any concerns with your doctor before the scan.

Certain things may make a CT scan of the abdomen less accurate. These include:

• Metallic objects within the abdomen, such as surgical clips
• Barium in the intestines from a recent barium study
• Stool or gas in the bowel
• Total hip replacement

• Your doctor will explain the scan to you and give you a chance to ask any questions.
• If your CT scan involves the use of contrast dye, you will be asked to sign a consent form that gives permission to do the scan. Read the form carefully and ask questions if anything is not clear.
• Tell the technologist if you have ever had a reaction to contrast dyes or if you are allergic to iodine.
• Generally, there is no fasting (not eating) requirement prior to a CT scan, unless a contrast dye is to be used. Your doctor will give you special instructions ahead of time if contrast is to be used and you won't be able to eat or drink.
• Tell your doctor about all the prescription and over-the-counter medicines, vitamins, herbs, and supplements you are taking.
• Tell the technologist if you are pregnant or think you may be pregnant.
• Tell the technologist if you have any body piercings on your chest or abdomen.
• Based on your medical condition, your doctor may request other preparations.
• If you are claustrophobic, discuss medicine to take beforehand with your doctor to help with the test.

You may have a CT scan as an outpatient or as part of your stay in a hospital. Procedures may vary depending on your condition.

Generally, a CT scan of the abdomen follows this process:

1. You will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.
2. If you are asked to remove clothing, you will be given a gown to wear.
3. If you are to have a scan done with contrast, an I.V. line will be started in your hand or arm for injection of the contrast dye. For oral contrast, you will be given a liquid contrast to drink. In some situations, the contrast may be given rectally.
4. You will lie on a narrow scan table that slides into a large, circular opening of the ring-shaped scanning machine. Pillows and straps may be used to help prevent movement during the scan.
5. The technologist will be in another room where the scanner controls are located. However, you will be able to see the technologist through a window at all times. Speakers inside the scanner will allow the technologist to talk to you and hear you. You will have a call button so that you can let the technologist know if you have any problems during the scan. The technologist will be watching you at all times and will be in constant communication.
6. As the scanner begins to rotate around you, X-rays will pass through your body for short amounts of time. You will hear clicking and whirring sounds, which are normal.
7. The X-rays absorbed by the body's tissues will be found by the scanner and sent to the computer. The computer will send the information into an image to be interpreted by the radiologist.
8. It will be important that you stay very still during the scan. You may be asked to hold your breath for a short time at various times during the scan.
9. If contrast dye is used, you will be removed from the scanner after the first set of scans has been completed. A second set of scans will be taken after the contrast dye has been given.
10. If contrast dye is used, you may feel some effects when the dye is injected into the I.V. line. These effects include a warm, flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea. These effects usually last only for a few moments. Let the technologist know if you feel pain or tingling at the I.V. site after injection.
11. You should tell the technologist if you have any trouble breathing, sweating, numbness, or heart palpitations.
12. When the scan has been completed, you will be removed from the scanner.
13. If an I.V. line was inserted, it will be removed.
14. You may be asked to wait for a short period of time while the radiologist examines the scans to make sure they are clear.

While a CT scan itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly if you've recently been injured or had surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

If contrast dye was used, you may be watched for a period of time for any side effects or reactions to the contrast dye. These include itching, swelling, rash, or trouble breathing. Tell the radiologist or your doctor right away if you notice any of these symptoms.

Tell your doctor if you notice any pain, redness, or swelling at the I.V. site after you go home. These could be signs of infection or other type of reaction.

If you are given contrast by mouth, you may have diarrhea or constipation after the scan.

Otherwise, you don't need any special care after a CT scan of the abdomen. You may go back to your usual diet and activities unless your doctor tells you differently.

Your doctor may give you other instructions depending on your situation.

Before you agree to the test or procedure, make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person's qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how you will get the results
• Who to call after the test or procedure if you have questions or problems
• How much you will have to pay for the test or procedure