Screening vs. diagnostic mammogram: What’s the difference?

Regular breast cancer screening helps find breast cancer early. This is when the chances for successful treatment are greatest.

A mammogram is considered the gold standard test to screen for breast cancer. There are two primary types of mammograms: a screening mammogram and a diagnostic mammogram.

Here, I’ll explain the purpose of each test, how they differ and why mammograms save lives.

What is a screening mammogram?

A screening mammogram is a test that uses low-dose X-rays to create images of each breast. It can help find lumps that are too small to feel.

Women at average risk for breast cancer should begin getting an annual mammogram at age 40. If you have an increased risk for breast cancer, such as a family history of the disease, your doctor will recommend a personalized screening plan, which may begin before age 40.

What is a diagnostic mammogram?

There are two main reasons your doctor may order a diagnostic mammogram:

• Abnormal findings are found on your screening mammogram, or
• You have symptoms of breast cancer, such as a lump in your breast or armpit, nipple discharge, certain types of breast pain or redness and thickening in the skin of your breast.  

A diagnostic mammogram takes more detailed images of the specific area(s) of concern. Diagnostic mammograms are often combined with a breast ultrasound, which uses sound waves to produce detailed images of the breast. This helps to further identify any abnormalities. It’s especially useful for people who have dense breasts. That’s because the extra glandular breast tissue can make it harder to spot cancer hiding in the tissue.

Keep in mind that needing a diagnostic mammogram doesn’t mean that you have cancer. Diagnostic mammograms help clinicians evaluate potentially abnormal findings. Most of these turn out to be benign, or non-cancerous.

If imaging suggests something needs further evaluation, your doctor may recommend a breast biopsy. During this procedure, a small sample of breast tissue is removed and examined under a microscope.

How screening and diagnostic mammograms compare

Both screening mammograms and diagnostic mammograms help detect breast cancer. Each test uses the same machine. A mammography technologist will perform each test, and a breast radiologist interprets the images.

Follow these tips to prepare:

• Do not wear deodorant, powder, perfume, lotion or ointment around the chest area before your appointment. These substances may show up on the X-rays and could be mistaken for a potentially significant finding.
• Wear a two-piece outfit, so you only have to remove your top.
• Do not wear jewelry. It could interfere with the imaging.

Here are the main differences between screening mammograms and diagnostic mammograms.

Purpose

A screening mammogram checks for breast cancer in women who are not showing any symptoms. A diagnostic mammogram is used to evaluate a specific area of the breast if abnormal findings were discovered during a screening mammogram, or if you have possible symptoms of breast cancer.

Time spent on exam

It usually takes about 15 minutes to take images of both breasts during a screening mammogram. That time is doubled for a diagnostic mammogram because more images are taken. So, it could take about 30 minutes.

Number of images

A screening mammogram takes four total images – two for each breast. A technologist will take several images during a diagnostic mammogram, so the radiologist can thoroughly review a specific area.   

How long it takes to get results

At UT MD Anderson, radiologists interpret screening mammograms the same day or the very next day. You can expect to see your results in MyChart as soon as the results are interpreted. We will also send the report to your doctor. We always read diagnostic mammograms the same day. You can expect results quickly – often in just a few minutes or hours after your appointment. 

Cost

Screening mammograms are covered by nearly every U.S. health insurance plan as an annual preventive test for women aged 40 and older. Coverage for diagnostic mammograms varies, so we encourage patients to contact the mammography facility and your health insurance provider to help determine coverage.    

Mammograms: Screening vs. Diagnostic

Regular breast cancer screening is important

Breast cancer screening saves lives. Screening mammograms help find breast cancer early, when it’s easier to treat.

Women at average risk for breast cancer should get a mammogram and clinical breast exam each year, starting at age 40.

If you have an increased risk for breast cancer, such as a family history or an inherited genetic mutation, you may need to start screening earlier, get additional tests and/or be tested more often. Your doctor will recommend a personalized screening plan.

Be aware of how your breasts look and feel, and see your doctor if you notice any changes or abnormalities.

Remember: breast cancer can often be cured when found and treated early.

Ethan Cohen, M.D., is a breast radiologist at UT MD Anderson.

Schedule your mammogram online or call 1-844-240-7092.