A mammogram is an x-ray picture of the breasts. It is used to find tumors and to help tell the difference between noncancerous (benign) and cancerous (malignant) disease.
How the test is performed
You will be asked to undress from the waist up and 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 to help flatten out 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.
Sometimes you will be asked to come back at a later date for more mammogram images. This does not always mean you have breast cancer. Rather, 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 that allows the x-ray image of the breast to be viewed and manipulated on a computer screen. It improves accuracy, but is not yet available everywhere.
How to prepare for the test
Do not wear 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 health care provider and the radiologist if you are pregnant or breastfeeding.
How the test will feel
The metal may feel cold. When the breast is pressed down, you may have some pain. However, this needs to be done to get good images.
Why the test is performed
Mammography is performed to:
- Screen healthy women for signs of breast cancer
- Further evaluate an abnormal finding on a mammogram
- Monitor and follow a woman who has had an abnormal mammogram
- Evaluate a woman who has symptoms of a breast disease, such as a lump, nipple discharge, breast pain, dimpling of the skin on the breast, or retraction of the nipple.
Screening mammograms are improving the detection of early breast cancer, when it is more likely to be curable.
- Some, but not all medical organizations recommend that women begin breast cancer screening at age 40 and have repeat mammograms every 1 to 2 years.
- All medical organizations recommend that women over age 50 have a screening mammogram every 1 to 2 years.
- Women with a mother or sister who had breast cancer should consider yearly mammograms earlier than the age at which their youngest family member was diagnosed.
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 or nothing to worry about. However, any new findings or changes must be further evaluated.
A radiology doctor 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 your breast tissue. Most calcifications are not a sign of cancer. See: Mammogram - calcifications for more information.
The American College of Radiology (ACR) has developed a grading system for radiology doctors to use when they report the results of a mammogram. Terms you may hear your doctor use include:
- Benign (noncancerous) finding
- Probably benign
- Suspicious abnormality
- Highly suggestive of malignancy or cancer
Often, the following tests are also needed:
- Additional mammogram views -- called magnification or compression views
Breast MRI exam
- Compare your current mammogram to your past mammograms. This will help tell whether you had an abnormal finding in the past, and whether it has changed.
- Sometimes, the doctor will use ultrasound to further examine your breast and determine the next best step
When mammogram or ultrasound results look suspicious, a biopsy is done to test the tissue and see if it is cancerous. See also:
What the risks are
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 breast-feeding.
Mammograms. National Cancer Institute Factsheet. Last reviewed September 22, 2010.
Qaseem A, Snow V, Sherif K, et al. Screening mammography for women 40 to 49 years of age: A clinical practice guideline from the American College of Physicians. Ann Intern Med. 2007;146(7):511-515.
Smith RA, Saslow D, Sawyer KA, et al. American Cancer Society guidelines for breast cancer screening: Update 2003. CA Cancer J Clin. 2003;53(3):141-169.
U.S. Preventive Services Task Force. Screening for Breast Cancer. U.S. Preventive Services Task Force recommendation statement: 2009 Nov.
Last reviewed 12/28/2010 by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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