Alternative names:

CT scan of the abdomen; retroperitoneum CT

How the test is performed:

The patient lies on a narrow table (gantry) that slides into the center of the scanner. The scanner looks like a tube surrounded by the imaging equipment. A contrast-media (dye) may be injected into a vein to help define certain tissues. The table will advance slightly (1/4 to 1/2 inch) between each scan to align for the next cross-section image. The technologist operating the computer may indicate when it is necessary to control breathing. A sound system is built into the machine to allow for communication with the patient during the test.

During the test, it is very important to remain still. If a patient is restless or traumatized, a sedative may be given. Each exposure takes a few seconds. The complete scan takes about 1 hour.

How to prepare for the test:

The health care provider may advise fasting for 4 to 6 hours if contrast dye is to be used or if sedation is anticipated (consult the health care provider).

The patient wears a hospital gown during the procedure. Sedatives may be administered if necessary. The patient may need to sign a consent form.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age: infant test or procedure preparation (birth to 1 year) toddler test or procedure preparation (1 to 3 years) preschooler test or procedure preparation (3 to 6 years) schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

The X-rays are painless. The primary discomfort may be from the need to lie still on the table.

If a dye is needed to increase the contrast between different tissues or organs, it is administered by injection into a vein. The injection may sting and the site may be tender to the touch for several minutes. Dye injections may cause a cool or warm sensation, a metallic taste and, in a few cases, hives.

Why the test is performed:

An abdominal (or retroperitoneal) CT may be recommended when there is a need to evaluate the soft tissue, including the organs, of the abdomen and/or retroperitoneal space.

The test may be indicated when there is abdominal injury; to determine the size, shape, and position of internal organs; to look for tumors, cysts, hemorrhage, or edema of the pancreas; to determine if a patient has liver disease or disease of the retroperitoneal space; to detect kidney masses; to determine the cause of unexplained stomach pain; or to evaluate the response to chemotherapy.

What the risks are:

CT scans and other X-rays are monitored and regulated to provide the minimum amount of radiation exposure needed to produce the image. CT scans provide low levels of radiation. During pregnancy, an abdominal CT scan is usually not recommended, because there is some evidence of risk to the fetus.

The most common dye used is iodine based. A person who is allergic to iodine may experience nausea, sneezing, vomiting, itching, or hives. Rarely, the dye may cause anaphylaxis (a life-threatening allergic response).

Special considerations:

A CT scan provides a better picture of soft tissues (internal organs) than conventional X-rays. The benefits of an abdominal-retroperitoneal CT scan usually far outweigh the risks of radiation exposure.