Screening vs. diagnostic mammograms, and what 3D mammography is
The difference between screening and diagnostic exams, what digital breast tomosynthesis adds, and what to ask a facility before you book.
When you call a mammography facility, one of the first questions will be whether you need a screening or a diagnostic mammogram, and many facilities will also ask whether you want, or your doctor ordered, 3D mammography. These choices affect how long the appointment takes, how it is billed and when you get your results. This guide explains the terms. It is general information, not medical advice: your healthcare provider can tell you which exam is right for you.
Screening mammograms
A screening mammogram is for people with no breast symptoms. It usually takes two X-ray views of each breast, and the images are often read later the same day or within a few days. The goal is to find cancer early, before it can be felt. The U.S. Preventive Services Task Force's 2024 recommendation is screening every two years for women aged 40 to 74; other medical organizations make somewhat different recommendations, and people at higher risk may be advised to start earlier or screen more often. That is a conversation to have with your healthcare provider.
Diagnostic mammograms
A diagnostic mammogram is used to investigate a symptom, such as a lump, skin change or nipple discharge, or to look more closely at something seen on a screening mammogram. It usually involves more views, sometimes magnified or compressed spot views, and a radiologist often reviews the images while you are still there and may add an ultrasound. Diagnostic exams usually need an order from a healthcare provider, take longer, and are billed differently from screening. Not every location offers them: many mobile units and some small sites do screening only, so ask before you book.
2D and 3D mammography
A standard digital mammogram produces two-dimensional images. Digital breast tomosynthesis (DBT), often called 3D mammography, takes many low-dose images from different angles as the X-ray tube moves in an arc, and a computer builds them into thin slices the radiologist can scroll through. Overlapping tissue can hide or mimic findings on a 2D image; looking at slices can help with both. Research has found that tomosynthesis can reduce recalls and find some additional cancers, especially for some people with dense breasts, and many facilities now use it routinely. Large studies are still comparing long-term outcomes.
Tomosynthesis units are covered by the same FDA certification under the Mammography Quality Standards Act as 2D units. FDA's facility list does not say which facilities offer it, so ask when you call.
Other breast imaging
- Breast ultrasound uses sound waves, not X-rays. It is often used to look at a specific area found on a mammogram or felt as a lump, and sometimes as a supplemental screening test for dense breasts.
- Breast MRI uses magnets and a contrast agent. It is used for some people at high risk and for specific diagnostic questions.
- Image-guided biopsy takes a small tissue sample using mammography, ultrasound or MRI to guide the needle. Breast centers that offer it can often schedule it soon after a suspicious finding.
Choosing between facilities
For a routine screening, convenience matters: a facility you can get to easily, at a time that works, is one you are more likely to keep going back to, and going back to the same facility makes it easier to compare your images over time. If you have dense breasts, a family history or a previous abnormal result, a full-service breast center that offers diagnostic imaging, ultrasound and biopsy in one place can shorten the time from a finding to an answer. Ask your healthcare provider which type of facility suits you.
If you have breast implants, tell the facility when you book. Imaging around implants takes extra views and experienced technologists, and some facilities schedule longer appointments for it.
What to expect at the appointment
- Many facilities ask you not to wear deodorant, antiperspirant, powder or lotion under your arms or on your breasts, because they can show up on the images.
- A two-piece outfit is easier, since you undress from the waist up.
- Compression is brief and helps produce clear images with a lower radiation dose. Tell the technologist if it is painful; they can often adjust.
- Bring the name and address of your previous mammography facility so your prior images can be requested for comparison.
- Tell the facility if you have breast implants, are pregnant or breastfeeding, or have had breast surgery.
Questions to ask a facility
- Do you offer 3D mammography (tomosynthesis), and is it standard or an extra charge?
- Do you do diagnostic mammograms and breast ultrasound here, or only screening?
- Can additional imaging be done the same day if needed?
- How and when will I receive my results?
- Do you offer evening or weekend appointments, or walk-in screening?
After the appointment
You should receive a plain-language summary of your results within 30 days, sooner if the result needs prompt follow-up; see our results guide. If you are called back for more imaging, that is common and most recalls turn out not to be cancer, but do schedule the follow-up promptly.
How this site can help
Every facility listed holds a current FDA MQSA certificate, and each profile shows its address and phone number. Hospital-based facilities are marked, and where we can match a facility to a Medicare-certified hospital we show that hospital's screening recall rate (Medicare measure OP-39) next to the national median, with an explanation. Use the compare tool to see up to three facilities side by side, then call to ask the questions above. If you have symptoms, contact your healthcare provider rather than waiting for a screening appointment.
General information only, current as of the date above. The information on Mammography Index is not medical advice and does not replace a doctor, nurse, discharge planner or other qualified professional. Do not use it to make decisions about diagnosis or treatment. If you have a medical emergency, call 911. Rules and programs change; check the official sources linked in this guide.