A mammogram is an x-ray picture of the breasts. It is used to find breast tumors and cancer.
How the Test is Performed
You will be asked to undress from the waist up. You will be given a gown to wear. Depending on the type of equipment used, you will sit or stand.
One breast at a time is rested on a flat surface that contains the x-ray plate. A device called a compressor will be pressed firmly against the breast. This helps flatten the breast tissue.
The x-ray pictures are taken from several angles. You may be asked to hold your breath as each picture is taken.
You may be asked to come back at a later date for more mammogram images. This does not always mean you have breast cancer. The doctor may simply need to recheck an area that could not be clearly seen on the first test.
Digital mammography is a newer technique. It allows the x-ray image of the breast to be viewed and manipulated on a computer screen. It improves accuracy, but it is not yet available everywhere.
How to Prepare for the Test
Do not use deodorant, perfume, powders, or ointments under your arms or on your breasts on the day of the mammogram. These substances may hide the images. Remove all jewelry from your neck and chest area.
Tell your doctor and the x-ray technologist if you are pregnant or breastfeeding.
How the Test will Feel
The compressor surfaces may feel cold. When the breast is pressed down, you may have some pain. This needs to be done to get good quality images.
Why the Test is Performed
Mammography is performed to screen women to detect early breast cancer when it is more likely to be cured. Mammography is recommended for:
Women starting at age 40, repeated every 1 to 2 years. (This is not recommended by all expert organizations.)
All women starting at age 50, repeated every 1 to 2 years.
Women with a mother or sister who had breast cancer at a younger age should consider yearly mammograms. They should begin earlier than the age at which their youngest family member was diagnosed.
Mammography is also used to:
Follow a woman who has had an abnormal mammogram.
Evaluate a woman who has symptoms of a breast disease. These symptoms may include a lump, nipple discharge, breast pain, dimpling of the skin on the breast, changes of the nipple, or other findings.
Discuss with your health care provider how often you need to have screening mammograms.
Breast tissue that shows no signs of a mass or calcification is considered normal.
What Abnormal Results Mean
Most abnormal findings on a screening mammogram turn out to be benign (not cancer) or nothing to worry about. New findings or changes must be further evaluated.
A radiology doctor (radiologist) may see the following types of findings on a mammogram:
A well-outlined, regular, clear spot (this is more likely to be a noncancerous condition such as a cyst)
Masses or lumps
Dense areas in the breast that can be breast cancer or hide breast cancer
Calcifications, which are caused by tiny deposits of calcium in the breast tissue (most calcifications are not a sign of cancer).
At times, the following tests are also needed to further examine mammogram findings:
Additional mammogram views -- called magnification or compression views
The level of radiation is low and any risk from mammography is very low. If you are pregnant and need to have an abnormality checked, your belly area will be covered and protected by a lead apron.
Routine screening mammography is not done during pregnancy or while breastfeeding.
American Cancer Society. American Cancer Society Recommendations for Early Breast Cancer Detection in Women Without Breast Symptoms. Last revised October 24, 2013. Available at: http://www.cancer.org/cancer/breastcancer/moreinformation/breastcancerearlydetection/breast-cancer-early-detection-acs-recs. Accessed November 12, 2013.
American College of Obstetricians and Gynecologists (ACOG). ACOG practice bulletin no.122. Breast cancer screening. Obstet Gynecol. 2011;118:372-382.
Katz VL, Dotters, D. Breast diseases: diagnosis and treatment of benign and malignant disease. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, Pa: Elsevier Mosby; 2012:chap 15.
National Cancer Institute: PDQ Breast Cancer Screening. Bethesda, MD: National Cancer Institute. Date last modified 10/30/2013. Available at: http://www.cancer.gov/cancertopics/pdq/screening/breast/healthprofessional. Accessed November 12, 2013.
U.S. Preventive Services Task Force. Screening for Breast Cancer. July 2010. U.S. Preventive Services Task Force. Available at: http://www.uspreventiveservicestaskforce.org/uspstf/uspsbrca.htm. Accessed November 12, 2013.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.