Approved by the Cancer.Net Editorial Board, 12/2019

An ultrasound is used to find a tumor by showing the tumor's exact location in the body. It can also help a doctor perform a biopsy. 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 are sent and bounce back when they reach the organs. A device called a transducer turns the sound waves into images.

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 and 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. They are specially trained to use the ultrasound machine.

A radiologist will interpret the results of the ultrasound. Radiologists are medical doctors who use 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.

Be sure to ask about the specific instructions for your ultrasound. Sometimes, preparing for the test is as simple as wearing comfortable, loose-fitting clothing to the visit.

Before your test, ask your insurance provider how much of the cost they will cover and how much you will need to pay. You should also talk with your health care team beforehand about any concerns you have about the ultrasound.

During the ultrasound

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.

After you are in the exam room, you will be instructed to remove some or all of your clothing. You may also need to take off jewelry or wear a hospital gown. This depends on the part of the body being examined.

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 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 produce better images by eliminating air pockets between the transducer and your skin.

Next, the technologist will press the transducer firmly against the gel and move it back and forth. You will need to lie still during the ultrasound. The technologist may ask you to hold your breath or adjust your position at certain times.

In some cases, the transducer attaches 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 the rectum to reach a prostate gland. Or it may be inserted into the vagina to see the uterus or ovaries.

During the ultrasound, the screen will display images of your organs and blood vessels. The technologist will use the computer to save images during the test.

Ultrasounds are usually painless, but you may feel some discomfort or pain during the exam.

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

After the ultrasound

When the procedure is over, the technologist will wipe off the gel and you can get dressed. A radiologist may enter the exam room to review the images right away or they will review the images later.

Depending on your results, you may need more tests. Your health care team will let you know if more tests are needed.

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

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?

More Information

National Library of Medicine: Ultrasound

RadiologyInfo.org: General Ultrasound