Ultrasound, also called sonography or ultrasonography, uses high-frequency sound waves to create a picture of internal organs. A tumor generates different echoes of the sound waves than normal tissue does, so when the waves are bounced back to a computer and changed into images, the doctor can locate a tumor inside the body.

The medical team

An ultrasound is performed in an ultrasound room at a doctor's office or in a hospital. The test is generally performed by an ultrasound technologist, called a sonographer, who is specially trained to operate the ultrasound machine.

The results of your ultrasound will be interpreted by a radiologist, a medical doctor who performs and interprets imaging tests to diagnose disease.

Questions to ask your doctor

Before having an ultrasound, consider asking your doctor the following questions:

• What will happen during the ultrasound?
• Who will perform the ultrasound?
• How long will the procedure take?
• Who will explain the results to me?
• When will I learn the results? How will they be communicated to me?
• What further tests will be necessary if the test results indicate cancer?

Preparing for the procedure

When you schedule your ultrasound, you will get detailed instructions on how to prepare. Specific preparation for an ultrasound depends on the part of your body being examined. For example, for ultrasounds on different parts of the abdomen, you may need to eat a fat-free meal the night before the examination; you may need to not eat or drink anything for up to 12 hours before the test; or you may need to drink a quart of water an hour before the exam and not urinate, so you will have a full bladder for the exam. Sometimes, no special preparations will be needed. Wear comfortable, loose-fitting clothing on the day of the exam.

You will be asked to sign a consent form that states you understand the benefits and risks of the ultrasound and agree to have the test done. Talk with your doctor about any concerns you have about the ultrasound.

During the procedure

When you arrive for your ultrasound, you will need to remove some or all of your clothing, depending on what part of your body will be examined. You will be given a hospital gown to wear. Jewelry that may interfere with the exam will also need to be removed.

You will lie on an examination table, either on your back or on your side, next to the ultrasound scanner. The scanner includes a computer; a video display screen; and a transducer, a hand-held device about the size of a bar of soap that is attached to the scanner by a long cord.

The technologist will spread a water-soluble gel on your skin over the area that is to be examined. The gel, which may feel cold when applied, helps to eliminate air pockets between the transducer and your skin, so the ultrasound will produce better images.

Next, the technologist will press the transducer firmly against the gel and move it back and forth across that area of your body. An image of your organs and blood vessels will appear on the video monitor. The technologist will use the computer to capture images periodically during the scan, and a radiologist may come into the exam room to review the images on the screen.

Ultrasounds are usually painless, but you may feel some discomfort as the transducer is pressed on your body, especially if you are required to have a full bladder for the exam.

You will need to lie still during the ultrasound. The technologist may ask you to hold your breath for several seconds at a time or to change your position on the table. If you are having a kidney ultrasound, you may need to lie on your stomach for part of the exam.

When the procedure is over, the technologist will wipe the gel off your body and you can get dressed. Depending on the area of the body being examined, the test can take 20 to 60 minutes to complete.

After the procedure

You can resume your normal activities, including driving, immediately after your ultrasound.

Additional resources

MedlinePlus, National Library of Medicine, National Institutes of Health: Interactive Tutorials: Ultrasound

RadiologyInfo (Public information website of the Radiological Society of North America and the American College of Radiology): Ultrasound - General

WebMD: Abdominal Ultrasound

Mayo Clinic: Ultrasound