This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on May 2, 2022.

An ultrasound is an imaging test that uses high-frequency sound waves to create pictures (called sonograms) of the body’s internal organs and tissues. A handheld device called a transducer is moved over the area of the body being examined, sending sound waves to organs and tissues. The transducer records the sound waves, or echoes, which are sent back, producing images projected on a computer screen. In real time, a medical provider is able to see internal organs at work and evaluate blood flowing through the vessels.

This non-invasive, typically painless procedure allows your doctor to view parts of the body that don’t usually show up on X-rays, such as muscles, ligaments or soft tissue. Ultrasounds are routinely performed on an outpatient basis, but they may be performed in hospitals as well.

Though an ultrasound alone cannot definitively show whether a mass is cancer, the technology is commonly used during the diagnostic process. This is because solid masses and abnormal tissue emit a different echo than fluid-filled cysts and healthy tissue. If ultrasound images show the former, further testing will be needed to diagnose cancer. A radiologist—a physician who specializes in diagnosing and treating injuries and diseases using medical imaging—or a sonographer, who is trained in ultrasound technology, are often able to tell the difference between benign and malignant masses by evaluating factors like their shape and location.

There are also internal ultrasounds called endoscopies. An endoscope—a thin, flexible tube-shaped device with a transducer attached to it— is inserted into the vagina, anus or mouth. Additionally, biopsies—the surgical removal of a tissue sample for testing—are often performed with the assistance of an ultrasound, to help guide the needle to the biopsy site.

At City of Hope, ultrasound is a regular component of our diagnostic procedures for many cancers, including stomach cancer, breast cancer, prostate cancer and ovarian cancer. Your City of Hope care team will discuss with you whether ultrasound is recommended, and if so, explain what you can expect from the procedure.1

How does an ultrasound work?

An ultrasound is a non-surgical procedure that allows your doctor to see inside the body in order to determine whether a mass is a solid tumor, often a sign of cancer, or a cyst filled with fluid, typically a benign growth. For most ultrasound procedures, no advance preparation is needed, though there are exceptions depending on the area of the body being evaluated.

Your medical provider will let you know if advance preparation is required. For example, if you’re having an pelvic ultrasound, you may be asked to drink a lot of water beforehand to fill your bladder. Sound waves travel through fluid, so a full bladder will improve the quality of the images. For some other body parts, you may be asked to fast the night before. It’s a good idea to wear comfortable clothing to your procedure.

Ultrasound benefits

Potential benefits of undergoing an ultrasound include:

  • The procedure usually is performed quickly.
  • You will not be exposed to radiation.
  • No advance preparation is typically needed.
  • The procedure may be performed on an outpatient basis. 
It is generally painless.

Ultrasound risks

Ultrasound is considered safe when performed by a properly trained health care provider.

What to expect during and after the procedure

Before the transducer is placed on the patient, gel will be applied to the area being studied. The gel eliminates air pockets that may form between the transducer and the skin. Air pockets can block the ultrasound waves.

The professional performing the test will glide the transducer along the area being examined. The only sensation you are likely to feel is light pressure from the transducer being pressed on the skin. Once the test is finished, the gel will be wiped off.

Common ultrasound procedures

Endoscopic ultrasound produces images of the esophagus, stomach, duodenum, colon, rectum, lungs, liver, gallbladder and pancreas.

Endobronchial ultrasound (EBUS) is often used to stage lung cancer and identify whether the cancer has spread beyond the lungs, such as to the lymph nodes. It may also be used to biopsy a sample of tissue or fluid from the lungs or lymph nodes in the chest. During this procedure, a bronchoscope (a thin, flexible scope) is connected to an ultrasound device and inserted into the patient’s mouth and guided through the trachea, allowing the doctor to capture images in the lungs and surround areas and to locate difficult-to-reach tumors. 

Doppler ultrasound evaluates blood flow through major arteries and veins, blood vessels, organs and tissues. This test is used to show blocked or reduced blood flow caused by things like a blood clot, plaque or inflammation.

Color Doppler overlays different colors for blood vessels, showing the speed and direction blood is traveling through the vessels. The different colors make the images easier to interpret.

Duplex ultrasound uses two types of ultrasound waves to produce images of blood vessels and the surrounding organs. The computer graphs the Doppler sounds, depicting the speed and direction the blood flows through the vessels.

Common types of ultrasound

Abdominal ultrasound is used to assess disease in organs located in the abdomen, including the liver, gallbladder, spleen, pancreas, bile ducts, kidneys and bladder. An abdominal ultrasound also may help pinpoint the cause of abdominal pain, gallstones, blood clots and other issues.

Transvaginal ultrasound is used to obtain better imaging of the pelvic organs, in addition to transabdominal imaging. A transducer is inserted in the vagina during a portion of this imaging test.

Transrectal ultrasound uses a transducer and inserts it in the rectum to view abnormalities in the rectum, pelvic lymph glands, the male prostate and women’s ovaries.

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