Breast Ultrasound to Screen for Breast Cancer

Breast ultrasound imaging is performed using high-frequency sound waves that humans cannot hear. The sound waves pass through the breast tissue and then are reflected back in different ways from different tissue structures to produce the images. 

A breast ultrasound provides imaging information that can assist in the diagnosis of cysts/fibrocystic changes, solid benign masses, cancers, abnormal lymph nodes, infectious processes and post-operative changes/scar tissue. It is especially helpful for evaluation of breast abnormalities which may be unclear because of dense breast tissue on a mammogram.

Breast ultrasound may be a Diagnostic exam or a Screening exam.

A diagnostic breast ultrasound is a non-invasive, painless test utilized to assess patients with symptoms that might indicate breast cancer or other breast disease. It also is commonly used to obtain more detail about a finding identified on mammography and for follow-up of previously identified lesions to look for changes. It is typically a limited exam, directed toward a specific area of interest in the breast.

Symptoms which would prompt a diagnostic ultrasound exam include:

• A palpable lump or area of thickening in the breast (felt by the patient or her physician)
• A spontaneous bloody or clear(translucent) nipple discharge
• New nipple inversion
• New skin changes of the breast
• Focal breast pain, not related to the hormonal cycle

Diagnostic breast ultrasound is performed by a technologist who has been specially trained. A water-soluble gel substance is placed on the skin of the breast and a small ultrasound probe (transducer) is rubbed over the breast to produce the images which are seen on the computer screen. The patient is scanned while lying on her back or slightly on her side. 

Only mild compression is applied with the probe and this rarely causes any patient discomfort. The images are always reviewed by the breast imaging radiologist who also typically examines the patient with ultrasound. The radiologist discusses the results and any follow-up recommendations with the patient and answers any questions. If a biopsy is recommended, our team will assist you in making arrangements for the procedure.

Screening breast ultrasound is performed only in patients who have no signs or symptoms of breast disease. Ultrasound is a supplemental screening tool which may be helpful in detection of cancers in women with dense breast tissue which might be obscured on mammography; it is not performed as a replacement for mammography. 

Extremely dense breast tissue can make cancer more difficult to detect on a mammogram. High breast density is one of the many known risk factors for breast cancer.  Your breast density is determined from the appearance of the breast tissue on mammography – it cannot be determined by clinical exam.   

When determining if you should have a screening ultrasound exam, your doctor will need to know your breast density (from your mammogram) and your breast cancer risk (from the cancer risk assessment).

If you have been told that you are at “High-Risk” for breast cancer (regardless of your breast density):

• You should begin annual screening with Breast MRI beginning at age 25-30
• You should include annual screening with mammography also beginning at least by age 30

If you are a high-risk patient and are unable to have an MRI, then screening ultrasound should be considered (these reasons might include pacemaker, non-MRI compatible implants such as aneurysm clip, pregnancy, history of allergic reaction to gadolinium, severe claustrophobia, severe obesity or poor kidney function).

If you are at Average risk for breast cancer, you should know your breast density (from your mammogram) to determine if screening ultrasound is indicated:

•  If you DO NOT have dense breast tissue, routine annual mammography is recommended and this would be performed as a 3D/tomosynthesis exam in our practice. 3D mammography is able to detect 1-2 additional cancers per 1,000 women screened. Screening breast ultrasound is not indicated.
• If you DO have dense breast tissue, annual mammography is recommended and this would be performed in our practice as a 3D/tomosynthesis exam. Screening breast ultrasound could be considered as a supplemental screening test in combination with mammography. The addition of ultrasound has been shown to detect 2 to 4 additional invasive cancers per 1,000 women screened.

Screening ultrasound requires a physician referral which allows you to discuss the pros/cons of additional imaging with your provider. Insurance coverage may vary.

A screening breast ultrasound is designed to evaluate the entirety of the breast tissue,  looking for lesions which may have been unclear on the mammogram. The exam may be performed as a “hand-held” procedure, performed by the technologist and/or radiologist rubbing the hand-held transducer over the entirety of both breasts and obtaining selected images to document findings. This technique is considered less reproducible and may take significant time to perform, especially if there are numerous findings. 

The Center for Women's Imaging at Mercy also offers Automated Breast Ultrasound - a state-of-the-art breast ultrasound technology. This equipment uses a special, enlarged probe (transducer) to automatically scan the entire breast and evaluate all breast tissue. This is performed with positioning assistance by the technologist.

The advantage of this method is that it is reproducible from year to year. It also typically takes less time to obtain the images (typically 10-15 minutes for the entire exam). Hundreds of images of the breast are obtained by this method and they are presented on a special computer workstation for the breast imaging radiologist to review/interpret. Because this is a screening exam, there is the potential for patients to be recalled for further diagnostic evaluation if an abnormality is identified.