What Is a Breast Ultrasound?

A breast ultrasound uses high-frequency sound waves to get a look at abnormal structures and tissues inside the breast. It is primarily used to help diagnose breast lumps or other abnormalities your doctor may have found during a physical exam or a mammogram. Ultrasound is a safe, noninvasive test and does not use radiation.

breast ultrasound
Verywell / JR Bee

Purpose of Test

An ultrasound is often performed when a mammogram shows something potentially abnormal that needs to be examined in more detail, or if a lump can be easily felt during a clinical breast exam

An ultrasound transmits high-frequency sound waves through breast tissue from a hand-held unit called a transducer. These sound waves bounce off of breast tissues and create an "echo." The echo is recorded by a computer that makes an image of the breast tissue and displays it on a monitor.

Ultrasound produces sharp, high-contrast images. In dense breast tissue, its images often allow a doctor to distinguish between a fluid-filled cyst and a solid mass. Mammograms don't make this distinction as accurately, though they are better than ultrasounds at detecting microcalcifications (which can be an early sign of breast cancer).

Often, breast abnormalities that are suspected of being cancerous after a mammogram can be identified as benign (non-cancerous) with a follow-up ultrasound examination. Benign breast abnormalities can include cysts and plugged milk ducts.

Breast structures that show up well on ultrasound include:

Advantages

Some advantages of ultrasound include that it:

Limitations

Ultrasounds have limitations, however. Disadvantages of this imaging technique include:

  • It can't image areas deep inside the breast.
  • Equipment can sometimes have problems.
  • It may have trouble distinguishing between abnormality and surrounding tissue.
  • It cannot show microcalcifications.

Ultrasound can be used to guide a surgeon during a breast biopsy, so the most accurate tissue sample can be taken. Your surgeon can also use an ultrasound to guide the needle during aspiration of a cyst in order to remove fluid. Lymph nodes can be distinguished from malignant tumors on ultrasounds as well.

If findings on an ultrasound warrant further testing, a breast MRI may be used. This test is usually reserved to screen women who have a high risk of breast cancer or to determine the extent of a tumor in women who have been diagnosed with cancer.

Risks and Contraindications

Breast ultrasounds are considered safe in and of themselves, but they sometimes lead to follow-up procedures, such as breast MRIs and biopsies, which do carry risks. Ultimately, even after further testing, the majority of findings on ultrasound images turn out to be benign.

Before the Test

If you have concerns about what the test entails or what it can and can't detect, talk to your doctor prior to the appointment.

Timing

Whether an ultrasound is done for screening, diagnostics, or to clarify a lump found by another exam, the procedure is largely the same. If you get mammogram results right away and a follow-up ultrasound is needed, you may have it the same day. If your mammogram results aren't ready for a day or so, you will have to come back for the ultrasound.

Either way, the breast ultrasound itself should only take about 15 minutes to half an hour.

Location

Breast ultrasounds are typically performed in an exam room at a breast center or a radiology testing center.

What to Wear

Since you'll have to undress from the waist up, it's best to wear a top and bottom, rather than a dress. Avoid putting on creams, lotions, or other products on your chest, as they can affects results.

Food and Drink

There are no restrictions as to what you can eat or drink, or what medications you can take, before your breast ultrasound.

Cost and Health Insurance

Most health insurance covers breast ultrasounds when ordered by a doctor for the diagnosis of a problem, but don't always cover them for routine screening. Call your insurance company to see what their policy is and to find out if you'll need pre-approval.

During the Test

A radiologist or sonographer will perform your breast ultrasound.

Pre-Test

You will most likely wait in a waiting room until your name is called. If you've just had a mammogram, you might go directly into the ultrasound room.

You will be asked to remove your bra and shirt (and necklace, if you're wearing one) and change into a gown. You will then lie on an exam table.

Throughout the Test

Ultrasound scanners consist of a computer console, a video display screen, and a transducer—a small hand-held device that the technician will move around on your breasts to get the images.

A radiologist or sonographer will apply a gel to the area of the body being studied and then move the transducer back and forth over the area of interest until the desired images are captured. You may be asked to change positions if necessary.

Ultrasounds are not painful, but you may feel some minor pressure from the transducer.

In some cases, the images will not be clear and the test will have to be repeated, usually while you're still at the center.

Post-Test

Once the images have been captured successfully, the gel will be wiped off your skin and you can get dressed; the gel does not usually stain or discolor clothing. There are no after effects of an ultrasound, and you will be able to resume your regular activities immediately.

Interpreting Results

Once your images are ready, a radiologist will analyze them. Sometimes this will be done while you are still in the office and the radiologist may discuss the results with you. Alternatively, the radiologist will send the results to the doctor who requested the exam, and they will share the results with you.

Follow-Up

If the ultrasound confirms that the areas of concern in your breast are benign, you will need no further testing. If an image suggests cancer, or the images are not conclusive, you will be asked to schedule a breast MRI and/or a biopsy.

Before undergoing further testing, however, you may wish to get a second opinion on your ultrasound images. One 2018 study done by researchers at Memorial Sloan Kettering Cancer Center in New York City looked at the results of a follow-up ultrasound done among women who brought their initial ultrasound images in for a second opinion. The second-opinion review disagreed with the original interpretation for 47% of the lesions (suspicious areas), averted 25% of originally recommended biopsies, and detected cancer in 29% of additional biopsies recommended. In the end, 35% of cancers diagnosed after the second-opinion review were not initially detected.

A Word From Verywell

Being referred for an ultrasound after a mammogram can be anxiety-provoking. Keep in mind that 10% to 12% of women are asked to get an ultrasound, and fewer than 1 in 10 women who receive follow-up tests are ultimately diagnosed with cancer. If you do end up getting a cancer diagnosis, early detection by tests such as ultrasounds can reduce the amount of treatment you'll require.

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