A mammogram is an X-ray of the breast. It’s a screening tool used to detect breast cancer. Together with regular clinical exams and monthly breast self-examinations, mammograms are a key element in the early diagnosis of breast cancer.

Even though thinking about getting one might make you uncomfortable, annual mammograms are important after age 40. According to the National Cancer Institute, breast cancer is the second most common cancer for women in the United States, after skin cancer.

In 2021, it’s predicted that there will be about 281,550 new cases of breast cancer in women. Learn about how mammograms work, who should get them, and more.

If your doctor orders a mammogram as a routine test to check for any cancer or changes, it’s known as a screening mammogram. In this type of test, you’ll get several images of your breast taken by a machine.

If you have a lump or any other symptom of breast cancer, your doctor will then order a diagnostic mammogram. If you have breast implants, you’ll probably need a diagnostic mammogram.

Diagnostic mammograms are more extensive than screening mammograms. They typically require more X-rays to get views of the breast from multiple positions. Your radiologist may also magnify certain areas of concern.

Some experts, including the American College of Obstetricians and Gynecologists and the National Comprehensive Cancer Network, recommend that women who are 40 years old and older should have a mammogram every 1 to 2 years. The American Cancer Society recommends regular screening beginning at age 45.

If you have a personal or family history of breast cancer, your doctor may recommend that you start screenings earlier, have them more often, or use additional diagnostic tools.

You’ll need to follow certain guidelines on the day of your mammography appointment. You should avoid applying the following substances, which can show up as white spots on the image:

  • deodorants
  • body powders
  • perfumes
  • ointments or creams on your breasts or underarms

In terms of annual mammograms, try to use the same facility every year if possible. This makes it easier to compare the results from year to year. If you’re visiting a new facility for the first time and have had prior mammograms, try to bring the old images with you.

Be sure to tell your radiologist before the exam if you’re pregnant or breastfeeding. In general, you won’t be able to receive a screening mammogram at this time, but if necessary, your doctor can order other screening methods, such as an ultrasound.

After undressing from the waist up and taking off any necklaces, a technician will give you a smock or gown that ties in the front. Depending on the testing facility, you may either stand or sit while the images are taken.

Each breast fits onto a flat X-ray plate. A compressor will then push the breast down to flatten the tissue. This provides a clearer picture of the breast. You might have to hold your breath for each picture. You may feel a small amount of pressure or discomfort, but it’s usually very brief.

During the process, your doctor will review the images as they are made. They may order additional images that show different views if something’s unclear or needs further attention. This happens quite frequently and is considered routine.

Digital mammograms

Digital mammograms are sometimes used if they’re available. These are especially helpful if you’re younger than 50 years old, who typically have denser breasts compared with older adults.

A digital mammogram transforms the X-ray into an electronic picture of the breast that saves onto a computer. Images are immediately visible, so your radiologist doesn’t have to wait for the images.

The computer can also help your doctor see images that might not have been very visible on a regular mammogram.

Yes, mammograms are safe.

As with any type of X-ray, you’re receiving exposure to a very small amount of radiation during mammography. However, the risk from this exposure is extremely low.

If a woman is pregnant and absolutely needs a mammogram before her delivery date, she’ll typically wear a lead apron during the procedure.

Images from a mammogram can help find calcifications, or calcium deposits, in your breasts. The test can also find cysts — which may come and go normally during some people’s menstrual cycles — and any cancerous or noncancerous lumps.

There’s a national diagnostic system for reading mammograms called the Breast Imaging Reporting and Database System (BI-RADS).

In this system, there are seven categories, ranging from zero to six. Each category describes whether additional images are necessary, and whether an area is more likely to have a benign (noncancerous) or cancerous lump.

Each category has its own follow-up plan. Actions on the follow-up plan may include:

  • gathering additional images
  • finding previous mammogram images for comparison
  • continuing regular screenings
  • making an appointment for follow-up in 6 months
  • performing a biopsy

Your doctor will review your results and explain the next steps to you during a follow-up appointment.