Mammogram: Types, How to Prepare, What Happens and Your Results
Updated: 5 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026 · How we review
Quick Answer: What is a mammogram?
A mammogram is an X-ray of your breast tissue. It is used both to screen people with no symptoms and to look more closely at a breast problem, and it can reveal early changes linked to breast cancer before you notice anything yourself. A mammogram cannot confirm cancer on its own, so an unusual finding leads to more imaging. [1]
What the research says
Screening mammograms lower the risk of dying from breast cancer. A 2024 systematic review found that, across randomized trials, screening reduced breast cancer deaths by a relative 15%. Over 10 years, the absolute benefit grew with age, from about 0.27 fewer deaths per 1,000 people in their 40s to 0.92 fewer per 1,000 at ages 70 to 74. The authors rated the certainty of the evidence as low to very low. (Bennett et al., Systematic Reviews, 2024) [2]
3D mammograms find more cancers than 2D alone, including in dense breasts. A meta-analysis of 13 studies found tomosynthesis (3D) with a computer-built 2D image raised cancer detection by about 60% in dense breasts and 32% in non-dense breasts compared with digital 2D mammography. Recall rates (being called back for more tests) were also lower. (Heywang-Köbrunner et al., European Journal of Radiology, 2022) [3]
Extra imaging can find more cancers in dense breasts after a normal mammogram. In a UK trial of 9,361 women aged 50 to 70 with dense breasts and a negative mammogram, supplemental scans found 17.4 cancers per 1,000 exams with abbreviated MRI and 19.2 per 1,000 with contrast-enhanced mammography, compared with 4.2 per 1,000 with automated ultrasound. (Gilbert et al., The Lancet, 2025) [4]
Key takeaways
A mammogram is a breast X-ray used for screening and for checking symptoms; it can spot changes before you feel them. [1]
People at average risk are generally advised to start yearly mammograms at 40, while those at higher risk may need to start earlier. [1]
Skip deodorant, perfume, lotion and powder on exam day, because they can show up on the images. [1]
The breast is pressed between two plates for a few seconds; this can be uncomfortable, but it passes quickly. [1]
Results usually come within a week and include your breast density and a BI-RADS category from 0 to 6. [1]
Screening with mammograms reduces breast cancer deaths, and 3D mammograms detect more cancers than 2D alone. [2][3]
What is a mammogram?
A mammogram (also called mammography) is an imaging test that uses low-dose X-rays to take pictures of the inside of your breasts. It can show abnormal areas and early changes that could lead to breast cancer. [1]
It is considered the gold standard for finding breast cancer and picks up about 85% of breast cancers. Like any test, it can miss some cancers and can flag areas that turn out to be harmless after more testing. [1]
A mammogram alone does not diagnose cancer. If something looks unusual, your care team will order more imaging to study that area in detail. [1]
Why is a mammogram done?
There are two main reasons to have a mammogram. Your provider will choose the type based on whether you have symptoms. [1]
Screening mammogram | Diagnostic mammogram | |
Who it is for | People with no breast symptoms | People with symptoms or an unclear screening result |
Main goal | Catch breast cancer early | Take a closer look at a specific concern |
Common triggers | Routine age-based schedule | New lump, nipple discharge or follow-up of an abnormal screen |
Typical length | About 15 to 20 minutes | Often longer, because more images may be needed |
Sources: [1]
What are the types of mammograms?
Mammograms are also grouped by how the pictures are taken. Both methods use X-rays and the same breast compression. [1]
2D mammogram (traditional): takes two pictures of each breast from different angles, usually top to bottom and side to side. [1]
3D mammogram (digital breast tomosynthesis): the X-ray arm moves in an arc and takes several images. A computer stacks them into thin slices, giving a three-dimensional view of the breast tissue. [1]
Research shows that 3D imaging combined with a computer-made 2D picture finds more cancers than 2D digital mammography alone. The gain was largest in dense breasts, and fewer people were called back for extra tests. [3]
Feature | 2D mammogram | 3D mammogram (tomosynthesis) |
How images are taken | Two fixed views per breast | Several X-rays as the arm sweeps in an arc |
What the radiologist sees | Flat pictures | Thin slices built into a 3D view |
Cancer detection vs 2D | Baseline | Higher, especially in dense breasts |
Callbacks for more tests | Baseline | Lower in pooled studies |
Who should get a mammogram, and how often?
If you are at average risk, you should generally begin yearly mammograms at age 40 and keep going for as long as you are in good health. [1]
If you have a higher risk or a family history of breast cancer, you may need to start before 40. Your provider may also add a breast ultrasound or breast MRI. [1]
Expert groups do not all agree on timing, so talk with your provider about a plan that fits your health history and past mammograms. [1] Large reviews show the benefit of screening on breast cancer deaths rises with age, from a small effect in your 40s to a larger one in your 60s and early 70s. [2]
How do you prepare for a mammogram?
A little planning makes the exam easier and helps get clear pictures. [1]
Do | Avoid |
Eat, drink and take your usual medicines | Deodorant, antiperspirant, perfume, lotion or powder on your chest and underarms |
Wear a two-piece outfit so you can undress from the waist up | Booking the week before or during your period, if you still menstruate |
Nurse or pump right before the exam if you are breastfeeding | Forgetting to mention pregnancy, implants or a recent vaccine |
Sources: [1]
What happens during a mammogram?
A radiologic technologist (a specialist trained to take X-ray images) guides you through each step. [1]
You remove clothing and jewelry above the waist and put on a gown that opens in the front. [1]
You stand in front of the machine, and one breast at a time is placed on a flat support plate. [1]
A clear plastic paddle lowers to press the breast flat for several seconds. This spreads the tissue so the images are sharp. [1]
The X-ray images are taken while your breast is compressed, and then the process is repeated on the other side. [1]
The technologist may check the pictures before you leave to make sure they are clear. [1]
A screening mammogram usually takes about 15 to 20 minutes. A diagnostic exam can take longer because extra views may be needed. [1]
Does a mammogram hurt?
The pressure from the plates can feel uncomfortable, but it lasts only a few seconds for each image. [1]
If it becomes painful, tell the technologist straight away. They may be able to adjust the plates to make you more comfortable. [1] Timing your exam away from your period can also help, because breasts are often tender then. [1]
What do mammogram results mean?
A radiologist (a doctor who reads imaging tests) reviews your pictures and often compares them with your earlier mammograms. Results usually arrive within a week by letter, phone call or your online health record. If you have not heard anything after a month, contact your provider or the imaging center. [1]
What else is in your report?
Breast density: how much of your breast is fibroglandular tissue (glands and supporting tissue) compared with fatty tissue. Providers are required by law to report it, because dense tissue can make cancer harder to see. [1]
BI-RADS category: a standard scoring system, numbered 0 through 6, that radiologists use to describe findings. Ask your provider what your number means for you. [1]
If you have dense breasts, research shows that some additional scans can find extra cancers that a normal mammogram did not show. In one large trial, abbreviated MRI and contrast-enhanced mammography found more cancers than automated ultrasound. [4] Ask your provider whether extra imaging makes sense for you.
What are the risks of a mammogram?
A mammogram exposes your breasts to a small amount of radiation. It is considered safe, and its benefits outweigh this risk. [1]
Brief discomfort from breast compression. [1]
False alarms: some areas flagged as unusual turn out not to be cancer after more tests. [1]
Missed cancers: a mammogram does not catch every breast cancer. [1]
Overdiagnosis: screening can find some cancers that might never have caused harm, according to trial data. [2]
When should you call your provider?
Do not wait for your next scheduled mammogram if you notice a change. Contact your provider promptly if you have: [1]
Questions to ask your provider
When should I start mammograms, and how often should I have them?
Is a 3D mammogram a good option for me?
Do I have dense breasts, and should I have any extra imaging?
Does my family history mean I should start screening earlier?
What does my BI-RADS category mean, and what are the next steps?
How will I get my results, and who should I call if I do not hear back?
Conclusion
A mammogram is a quick breast X-ray that can find early changes before you feel them. Simple steps, like skipping deodorant and choosing a time when your breasts are less tender, make the exam easier. [1]
Regular screening lowers the chance of dying from breast cancer, and newer 3D imaging finds more cancers than 2D alone. [2][3] Talk with your provider about when to start, how often to go and whether your breast density calls for any extra tests.
Keep learning: Read our guides to breast cancer, breast cysts and fibrocystic breasts. For more, see the National Cancer Institute's page on mammograms.
FAQ
What is a mammogram?
A mammogram is an X-ray of your breast tissue that can show early changes linked to breast cancer, often before you notice symptoms. [1]
Why is a mammogram done?
It is done to screen people without symptoms and to check symptoms such as a new lump or nipple discharge, or an unclear screening result. [1]
How do I prepare for a mammogram?
Eat and take medicines as usual, wear a two-piece outfit, and skip deodorant, perfume, lotion and powder. Avoid booking the week before or during your period. [1]
Does a mammogram hurt?
Compression can feel uncomfortable, but it lasts only seconds. Tell the technologist if it hurts so they can adjust the plates. [1]
How long does a mammogram take?
A screening mammogram usually takes about 15 to 20 minutes. A diagnostic exam can take longer. [1]
What is the difference between a 2D and 3D mammogram?
A 2D mammogram takes two flat views of each breast. A 3D mammogram takes several images in an arc and builds them into slices. [1]
When will I get my mammogram results?
Results usually arrive within a week. If you have not heard back in a month, contact your provider or the imaging center. [1]
Does an abnormal mammogram mean I have cancer?
No. It means an area needs a closer look, usually with another mammogram, an ultrasound or an MRI. [1]
How often should I get a mammogram?
People at average risk are generally advised to have yearly mammograms starting at 40. Those at higher risk may start earlier. [1]
When should I call my provider about a breast change?
Call promptly if you notice a new lump, nipple discharge, skin changes or any other new breast symptom. [1]
Related Reading
Molecular Breast Imaging (MBI): Finding Cancer in Dense Breasts explains the tracer-based breast test for women with dense breasts.
Digital Breast Tomosynthesis (3D Mammogram): Benefits, Prep and Results explains 3D mammography and how it compares with a standard mammogram.
Learn more in our guide to Breast Cancer: Symptoms, Causes, and Treatment.
Learn more in our guide to Breast Cysts: Symptoms, Causes, and Treatment.
Learn more in our guide to Fibrocystic Breasts: Why They Happen, What the Lumps Mean, and What Actually Helps.
Learn more in our guide to Breast Cancer in Young Women: Early-Onset Diagnosis, Risk Factors, and What to Do Next.
Learn more in our guide to Inflammatory Breast Cancer: Symptoms, Causes, and Treatment.
Stereotactic Breast Biopsy: Why It's Done, What to Expect, Recovery and Results explains the mammogram-guided biopsy used for calcifications that can't be felt.
Core Needle Breast Biopsy: Procedure, Recovery and Results explains the needle biopsy used to check breast changes for cancer.
References
Cleveland Clinic. Mammogram (Mammography). Cleveland Clinic. Last updated August 18, 2026. https://my.clevelandclinic.org/health/diagnostics/4877-mammogram
Bennett A, Shaver N, Vyas N, et al. Screening for breast cancer: a systematic review update to inform the Canadian Task Force on Preventive Health Care guideline. Syst Rev. 2024;13(1):304. PMID 39702409. https://doi.org/10.1186/s13643-024-02700-3
Heywang-Köbrunner SH, Jänsch A, Hacker A, et al. Tomosynthesis with synthesised two-dimensional mammography yields higher cancer detection compared to digital mammography alone, also in dense breasts and in younger women: A systematic review and meta-analysis. Eur J Radiol. 2022;152:110324. PMID 35576720. https://doi.org/10.1016/j.ejrad.2022.110324
Gilbert FJ, Payne NR, Allajbeu I, et al. Comparison of supplemental breast cancer imaging techniques-interim results from the BRAID randomised controlled trial. Lancet. 2025;405(10493):1935-1944. PMID 40412427. https://doi.org/10.1016/S0140-6736(25)00582-3
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
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