Approved by the Cancer.Net Editorial Board, 06/2018

An ultrasound is used to find a tumor. It can also help a doctor perform a biopsy. It shows the tumor’s exact location in the body. A biopsy removes a small amount of tissue for examination.

How does an ultrasound work?

An ultrasound is an imaging test. It is also called sonography or ultrasonography. It uses high-frequency sound waves to create pictures of internal organs. The sound waves hit the organs and bounce back to a device called a transducer. The transducer turns the sound waves into images that are shown on a computer.

The sound waves echo differently when bouncing off abnormal tissue and healthy tissue. This helps the doctor detect a potential tumor.

An ultrasound test does not have any x-ray exposure. This means that it is safe to have during pregnancy.

Who does my ultrasound?

An ultrasound may be done in a doctor's office or at a hospital.

An ultrasound technologist usually performs the test. This person is also called a sonographer. This technologist is specially trained to use the ultrasound machine.

A radiologist interprets the results of an ultrasound. A radiologist is a medical doctor who uses imaging tests to diagnose disease.

Getting ready for an ultrasound

How you need to prepare for an ultrasound depends on the part of the body being examined. For example, these are typical instructions for an ultrasound of the abdomen:

  • Eat a fat-free meal the night before.

  • Avoid eating or drinking for up to 12 hours before the test.

  • Drink a quart of water an hour before the test, and keep a full bladder.

Sometimes, preparing for the test is as simple as wearing comfortable, loose-fitting clothing to the visit.

Talk with your insurance provider before your test to find out how much of the cost they will cover and how much you will need to pay.

Once you arrive at the doctor's office or hospital, you will be asked to sign a consent form. This form states that you understand the risks and agree to have the test.

Talk with your health care team about any concerns you have about the test.

During the ultrasound

When you arrive for your ultrasound, you will remove some or all of your clothing. This depends on the part of the body being examined. In some cases, you will wear a hospital gown. You may also need to take off jewelry.

You will lie on an exam table next to the ultrasound scanner. The scanner includes a computer, a screen, and a transducer. The transducer is a hand-held device that is attached to the scanner by a long cord.

The ultrasound technologist will spread a gel on your skin over the body part being examined. The gel helps eliminate air pockets between the transducer and your skin. This allows the ultrasound to produce better images.

Next, the technologist will press the transducer firmly against the gel and move it back and forth. The screen will display images of your organs and blood vessels. The technologist will use the computer to save images during the test.

You will need to lie still during the ultrasound. The technologist may ask you to hold your breath for several seconds at a time. You may also need to change your position on the table.

In some cases, the transducer is attached to a probe that is covered with gel. The technician gently inserts the probe into the body. For example, the probe may be inserted into a man’s rectum to see the prostate. Or, it may be inserted into a woman’s vagina to see the uterus or ovaries.

Ultrasounds are usually painless. But you may feel some discomfort when the transducer is pressed on your body.

The test can take 20 to 60 minutes. The time depends on the body part being examined.

At the end, a radiologist may enter the exam room to review the images.

After the ultrasound

When the procedure is over, the technologist will wipe the gel off your body. Then, you may get dressed.

After your ultrasound, you may return to your usual activities. This includes driving.

If the test results show something concerning, you may get more tests that can provide more information.

Questions to ask your health care team

Consider asking the following questions before having the test:

  • What will happen during the ultrasound?

  • Who will perform the ultrasound?

  • Is the radiologist certified by the American Board of Radiology?

  • How long will the ultrasound take?

  • How accurately can an ultrasound find cancer?

  • When will I learn the results? How will they be communicated to me?

  • Who will explain the results to me?

  • What other tests will I need if the ultrasound finds evidence of cancer?

Related Resources

Cancer.Net Podcast: Ultrasound - What to Expect

More Information

National Library of Medicine: Ultrasound

RadiologyInfo.org: General Ultrasound