A breast ultrasound helps evaluate breast lumps, cysts, inflammatory changes, and abnormalities found on a breast exam.
This test can complement mammography, especially in people with dense breast tissue or higher breast cancer risk.
Breast ultrasound is quick and painless, and the images are reviewed by a radiologist using the BI-RADS classification.

A breast ultrasound is an imaging test used to evaluate the internal structures of the breast. It can help identify breast lumps, breast cysts, breast cancer, or inflammatory changes, for example.

This test is usually ordered when a breast abnormality is found on a mammogram. It can also be used to guide a breast biopsy.

Breast ultrasound is a simple, quick, and painless test. No preparation is needed, although the person will usually be asked to remove their shirt and bra, when applicable.

technician performing a breast ultrasound

What it is used for

A breast ultrasound is used to evaluate breast abnormalities found during a breast exam, mammogram, or MRI, such as benign cysts, solid lumps, or breast cancer.

According to the American College of Radiology, supplemental screening may be considered based on a person’s breast density and individual breast cancer risk, especially in people with very dense breasts.

Breast ultrasound may also be used to guide a breast biopsy, helping the doctor locate the breast lump so a needle can be inserted to collect a sample from the lesion.

When it is recommended

Breast ultrasound may be recommended to:

Differentiate between benign and malignant lumps
Detect seromas and hematomas
Check the condition of breast implants
Investigate the cause of breast pain or inflammatory changes
Assess the characteristics of palpable lumps
Monitor lumps

Breast ultrasound may also be recommended for people who are pregnant or at high risk of breast cancer who cannot be exposed to radiation from a mammogram or MRI.

The doctor may also recommend a breast ultrasound to evaluate how well chemotherapy and/or radiation therapy is working to treat breast cancer.

Breast ultrasound vs mammogram

A breast ultrasound is not the same as a mammogram and does not replace this test. It is only used to complement breast evaluation.

Mammography is still the most recommended test for identifying breast cancer.

What to expect

A breast ultrasound is usually performed by a trained sonographer in specialized clinics or hospitals, and the images are interpreted by a radiologist. It is a test that does not cause pain or discomfort.

To perform a breast ultrasound, the sonographer usually follows these steps:

Asks the person to remove their shirt and bra, when applicable, and put on a gown that opens in the front
Asks the person to lie on the exam table with one arm positioned behind the head
Applies gel to the ultrasound transducer and to the breast being examined
Places the transducer on the skin and moves it over the breasts
Checks the images shown on the computer during the exam
Saves images for the radiologist to review and include in the ultrasound report

During the ultrasound, the sonographer captures images that allow the radiologist to assess the characteristics of a lump or cyst in the breast, such as whether it is solid or filled with fluid, its shape, and whether its borders are well-defined or poorly defined.

Based on the American College of Radiology’s BI-RADS system, breast ultrasound results are organized into standardized categories that help radiologists communicate findings and guide follow-up recommendations. This system divides findings into categories to help determine the risk of breast cancer.

Automated breast ultrasound

Automated breast ultrasound, or ABUS, is a type of breast ultrasound performed with a device that has a larger transducer and automatically scans the breast. It is commonly used as a supplemental screening test for people with dense breast tissue.

Although ABUS scans nearly the entire breast and generates hundreds of images, a traditional handheld breast ultrasound may still be needed if an abnormality is found.

Interpreting results

Breast ultrasound results are reported according to the BI-RADS classification:

BI-RADS category	What it means
BI-RADS 0	Incomplete assessment, meaning another imaging test is needed to detect possible abnormalities.
BI-RADS 1	Normal exam, with no abnormalities found. Only routine follow-up according to the woman’s age is recommended.
BI-RADS 2	Benign findings, such as simple cysts, intramammary lymph nodes, implants, or changes after surgery. Usually, this type of finding represents benign solid lumps that have been stable for 2 years.
BI-RADS 3	Probably benign findings, meaning the exam should be repeated in 6 months, and then at 12, 24, and 36 months after the first abnormal exam. Findings in this category may include lumps that suggest fibroadenoma, or complex and clustered cysts. The risk of malignancy is up to 2%.
BI-RADS 4	Suspicious abnormality, meaning a biopsy is recommended. Findings may include solid lumps without features that suggest they are benign. This category may be subdivided into: 4A - low suspicion; 4B - intermediate suspicion; and 4C - moderate suspicion. The risk of malignancy ranges from 3% to 94%, and repeat testing is needed to confirm the diagnosis.
BI-RADS 5	Highly suspicious abnormality for malignancy. A biopsy is needed, and in this case, the lump has a 95% chance of being malignant.
BI-RADS 6	Breast cancer previously confirmed by biopsy. This type of BI-RADS category is used to monitor response to treatment, such as chemotherapy or radiation therapy.

Breast ultrasound results should be interpreted by a breast specialist, gynecologist, or oncologist, together with the mammogram and/or breast MRI.

Breast Ultrasound: When It's Done & What to Expect