What Is a Breast Ultrasound?

Breast ultrasounds are an imaging test that uses inaudible sound waves to look inside your breasts. Healthcare providers use this non-invasive test as a follow-up to an abnormal finding from a breast cancer screening test called a mammogram. They might also be ordered because of concerning findings from a magnetic resonance imaging (MRI), or clinical breast exam. 

Breast ultrasounds provide detailed, high-contrast images that help radiologists decide if a lump is solid or fluid-filled. It is an especially helpful tool for women with dense breasts.

This article reviews the purpose of a breast ultrasound, advantages, limitations, risks, what to expect, cost, and how results are interpreted.

breast ultrasound
Verywell / JR Bee

Purpose of Test

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.

If your healthcare provider discovers a lump during a clinical breast exam or something abnormal on a mammogram, a breast ultrasound is typically ordered.

Breast ultrasounds provide detailed, high-contrast images that help radiologists determine if a lump is solid (such as a benign fibroadenoma or cancer) or fluid-filled (such as a benign cyst). It is an especially helpful tool for women with dense breasts.

In addition to evaluating breast lumps, a healthcare provider may request a breast ultrasound to:

  • Assess nipple discharge
  • Evaluate breast inflammation and/or infection (mastitis)
  • Monitor breast implants
  • Assess symptoms, such as breast pain, redness, and swelling
  • Examine skin changes, such as discoloration
  • Monitor existing benign breast lumps

A breast ultrasound is a complement to other screening tests. It cannot be used to determine whether a lump is cancerous or not.

Advantages

Ultrasounds 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.

Additional advantages of ultrasounds include:

  • They produce high-contrast images. Ultrasounds can help distinguish fluid-filled lumps (cysts) from solid lumps that may be cancerous or benign (noncancerous). They can also locate nonpalpable masses (lumps that you can't feel),
  • They are Painless. Most ultrasounds are completely painless.
  • They can detect changes in dense breasts. When used in addition to mammograms, ultrasounds can increase the detection of early-stage breast cancers in women with dense breast tissue
  • They do not use radiation. Unlike mammograms, ultrasounds do not use radiation. For this reason, ultrasounds can be a good tool for women who are pregnant or breastfeeding, have breast implants, or are age 30 and younger.
  • They are affordable. Is less expensive than a computed tomography (CT) scan or breast magnetic resonance imaging (MRI)

Limitations

Disadvantages of this imaging technique include:

  • Cannot image areas deep inside the breast. It can't image areas deep inside the breast.
  • Unable to detect early signs of cancer. The images produced during ultrasounds cannot pick up the small deposits of calcium (microcalcifications), which can be an early sign of breast cancer

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

When your healthcare provider recommends a breast ultrasound, they will talk to you about why they are ordering it. These concerns could be about your mammogram, a breast examination, or the symptoms you are having.

You can also expect to talk about how quickly it needs to be scheduled, where it will be done, if you need to schedule it, or if someone is going to call you.

If you have concerns about what the test entails or what it can and can't detect, talk to your healthcare provider before 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 affect 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 healthcare provider 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 they discuss the results with you during your appointment. At other times they send results to the healthcare provider who requested the test. In this case, your provider should have results within one-two days.

Healthcare providers use the Breast Imaging Reporting and Data System (BI-RADS) to describe ultrasound results. This is the same system used for mammogram results. The results are sorted into BI-RADS categories 0 through 6 as follows:

  • Category 0: Incomplete or needs additional imaging evaluation or prior mammogram results for comparison
  • Category 1: Negative
  • Category 2: Benign (not cancerous)
  • Category 3: Probably benign (very low chance of cancer)
  • Category 4: Suspicious for malignancy (cancer), consider biopsy. This is sometimes categorized even further into low, moderate, or high suspicion of malignancy.
  • Category 5 - Highly suggestive of cancer (>95 % probability of malignancy)
  • Category 6 - Known, biopsy-proven cancer

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.

Some women prefer to get a second opinion before undergoing further testing. One 2018 study found a second opinion prevented 25% of the originally recommended biopsies. It also found that 35% of the second opinions detected cancer that was not originally found.

Summary

Breast ultrasounds are often ordered as a follow-up to an abnormal finding from a mammogram (breast cancer screening test). They might also be ordered because of concerning findings from a magnetic resonance imaging (MRI), or clinical breast exam. 

Breast ultrasounds provide high-contrast images that help radiologists decide if a lump is solid or fluid-filled. It is an especially helpful tool for women with dense breasts. 

Breast ultrasounds are safe, non-invasive, do not require radiation, and usually take about 15 minutes to complete. Most are covered by insurance when your healthcare provider orders them for a suspicious finding but may not be covered when used as a screening tool. 

Ultrasound findings are characterized by the BI-RADS system. If it confirms a mass is benign, you won’t need more tests. If it looks like it could be cancer or it is not conclusive, your healthcare team may order further testing such as a biopsy or MRI.

A Word From Verywell

Being referred for a breast ultrasound after a mammogram can be anxiety-provoking. It may be helpful to note that a biopsy will only be recommended to less than 3% of women who have a breast ultrasound.

Learning about the reasons for the ultrasound and what to expect are great first steps. Ask your healthcare provider if you are not sure why they ordered it for you.

If you were to receive a cancer diagnosis, keep in mind that early detection by tests such as ultrasounds can reduce the amount of treatment you'll require.

Frequently Asked Questions

  • What does a breast ultrasound show that a mammogram doesn’t?

    Breast ultrasounds look at possible abnormalities from the mammogram to see if they are fluid-filled, solid, or a mixture of both. Ultrasounds are also better at distinguishing lumps in dense breast tissue. They provide high-contrast images that help the radiologist know if the lump is a cyst, benign (not-cancer) lump, or possibly cancer. It also helps them decide if further diagnostic tests such as a biopsy or magnetic resonance imaging (MRI) are needed to rule out cancer.

  • What percentage of breast ultrasounds are cancer?

    In a study done in 2019, less than 3% of women who have a breast ultrasound will be recommended for biopsy. Of the small percentage of women who have suspicious findings or a biopsy, 2%–30% had cancer.

  • What does breast cancer look like on an ultrasound?

    Radiologists consider a mass suspicious when it appears hypoechoic (solid or dense), dark with an irregular, spiky, or branching edge. They are also often taller than they are wide.

    However, it’s important to note that benign (non-cancerous) tumors can have some of these characteristics as well. An ultrasound-guided needle biopsy is needed to differentiate cancer from non-cancerous lumps.

Originally written by
Pam Stephan
Pam Stephan is a breast cancer survivor.
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