Mammograms are X-ray images of the breasts that check for cancer and other changes in breast tissue. A mammogram can be used for screening or diagnosis.

Screening mammogram

A screening mammogram checks for breast changes that could be cancer in people who have no signs or symptoms. The goal is to find cancer when it is small and when treatment may be less invasive.

Experts and medical organizations have different recommendations on when to start regular mammograms and how often to repeat them. In general, healthcare professionals recommend that females with an average risk of breast cancer begin screening with mammograms at age 40. Most people should repeat the screening every year.

Talk with your healthcare professional about your risk factors, your preferences, and the benefits and risks of screening. Together, you can decide the best schedule for your screening mammograms.

Diagnostic mammogram

A diagnostic mammogram is used to study suspicious breast changes, such as a new breast lump, breast pain, a change in the way the skin looks, nipple thickening or nipple discharge. It also can be used to look into concerning findings on a screening mammogram. A diagnostic mammogram includes more images of the breast.

Risks and limitations of mammograms include:

Mammograms use a small amount of radiation

A mammogram exposes you to a very low dose of radiation. For most people, the benefits of regular mammograms are greater than the risks of exposure to this low dose of radiation.

Having a mammogram may lead to more testing

If your healthcare professional finds something that's not expected on your mammogram, you may need other tests. These tests might include extra imaging tests, such as an ultrasound, or a procedure called a biopsy to take a sample of breast tissue for lab testing. However, most findings from mammograms aren't cancer.

If your mammogram shows something concerning, the doctor who examines the images, called a radiologist, may want to compare them with previous mammograms. If you have had mammograms at other facilities, your radiologist may ask for your permission to get those images.

Screening mammography can't detect all cancers

Some cancers found during a physical exam may not be seen on a mammogram. A cancer may be missed if it is too small or if it is in an area that is hard to see with mammography, such as the armpit.

Not all cancers found on mammograms can be cured

Some breast cancers are aggressive, grow rapidly and quickly spread to other parts of the body. Finding breast cancer on a mammogram doesn't always lead to a cure.

To prepare for a mammogram:

• Schedule the test for a time when your breasts are least tender. If you menstruate, that's usually during the week after your menstrual period.
• Bring your prior mammogram images. If you're going to a new facility for your mammogram, ask to have any prior mammograms placed on a CD. Bring the CD with you to your appointment so that the radiologist can compare past mammograms with your new images.
• Do not use deodorant before your mammogram. Avoid using deodorants, antiperspirants, talcum powders or lotions under your arms or on your breasts. Sometimes these products can show up on a mammogram and cause confusion.

During the test

At the mammogram facility, you are given a gown and asked to remove neck jewelry and clothing from the waist up.

During the procedure, you stand in front of an X-ray machine made for mammography. A member of your healthcare team places one of your breasts on a platform and adjusts the platform to your height. Your head, arms and torso are positioned to ensure a clear view of your breast.

A clear plastic plate gradually presses your breast against the platform. This pressure lasts for a few seconds to spread out the breast tissue. The pressure isn't harmful, but it can cause some discomfort. Tell your care team if the discomfort becomes too much.

Your breast must be compressed to even out its thickness and allow the X-rays to pass through the breast tissue. The pressure also keeps your breast still, which reduces blurring from movement and lowers the dose of radiation needed. During the brief X-ray exposure, you stay still and hold your breath.

After the test

After your mammogram, you may wait while your care team checks the quality of the images. If the images are not clear, you may have to repeat part of the test. The entire procedure usually takes less than 30 minutes. Afterward, you may dress and resume your usual activities.

Mammography produces mammograms, which are black-and-white images of your breast tissue. Mammograms are digital images that appear on a computer screen. A doctor trained to read imaging tests, called a radiologist, reviews the images.

The radiologist looks for signs of cancer and other conditions that may need further testing, follow-up or treatment. The results are put into a report and shared with your care team. Ask your healthcare professional when and how you will receive the results.