The short answer
A mammogram uses low-dose x-rays to image breast tissue and is the main screening test. An ultrasound uses sound waves and no radiation, and is often used to look more closely at a specific area or to tell a fluid-filled cyst from a solid lump.
A mammogram uses low-dose x-rays and is the main tool for breast cancer screening.
An ultrasound uses sound waves, not radiation, and is often used to look more closely at a specific spot.
Ultrasound is good at telling a fluid-filled cyst from a solid lump.
The two are often used together rather than as either-or; ultrasound frequently follows up on a mammogram finding.
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The full explanation.
The short version
Mammograms and ultrasounds are both used to look at breast tissue, but they work differently and are good at different things. A mammogram uses low-dose x-rays and is the main tool for breast cancer screening. An ultrasound uses sound waves — no radiation — and is often used to look more closely at a specific area. Rather than being either-or, they are frequently used together.
How a mammogram works
A mammogram is an x-ray picture of the breast that uses a low dose of radiation. It is the main test used to screen for breast cancer, and it can find some changes very early, before they can be felt. Screening mammograms are done on a schedule your care team recommends.
How an ultrasound works
An ultrasound uses sound waves to create pictures of the tissue inside the breast. It does not use radiation. Ultrasound is often used after a mammogram or a physical exam to take a closer look at a specific spot — and it is particularly good at telling whether a lump is a fluid-filled cyst or a solid mass.
Why the two are often used together
The tests complement each other. A mammogram might show an area that needs more detail, and an ultrasound can help clarify it. Using them together often gives a clearer picture than either test alone. Depending on the results, further tests — sometimes including a biopsy — may be recommended.
Does ultrasound replace a mammogram?
Usually not. Ultrasound is generally used alongside mammography rather than as a substitute for routine screening. Which tests you need, and how often, depends on your individual situation.
What to ask
Ask your care team which test or combination they recommend and why, whether it is for routine screening or to look at a specific finding, what might happen next depending on the result, and when you will go over the results together.
Words to know
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Common questions
▸What is the difference between a mammogram and an ultrasound?
A mammogram uses low-dose x-rays to make pictures of breast tissue and is the main screening test. An ultrasound uses sound waves and no radiation, and is often used to look more closely at a specific area or to tell whether a lump is fluid-filled or solid.
▸Is an ultrasound better than a mammogram?
Neither is simply 'better' — they show different things. Mammography is the main screening test and can find changes very early. Ultrasound is often used to add detail about a specific finding. Frequently the two are used together.
▸Why would I need both?
A mammogram might show an area that needs a closer look, and an ultrasound can help clarify it — for example, showing whether a lump is a fluid-filled cyst or a solid mass. Using them together often gives a clearer picture than either alone.
▸Does an ultrasound replace my regular mammogram?
Usually not. Ultrasound is generally used alongside mammography rather than as a substitute for routine screening. Your care team advises which tests you need and how often, based on your individual situation.
Questions to ask your doctor
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Your next step
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