Alternative names

A mammogram is an X-ray picture of the breasts. It is used to detect tumors and cysts and to help differentiate benign (noncancerous) and malignant (cancerous) 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, and 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.

How to prepare for the test

Do not wear deodorant, perfume, powders, or ointments under the arms or on the breasts on the day of the mammogram. These substances may obscure the images. Remove all jewelry from your neck.

Notify your health care provider (and/or the radiologist) if you are pregnant or breast-feeding.

How the test will feel
When the breast is compressed, there may be some discomfort.

Why the test is performed

Mammography is performed to screen healthy women for signs of Breast cancer. It is also used to 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 important for early Breast cancer detection. The American Cancer Society recommends mammogram screening every year for all women age 40 and older. The National Cancer Institute recommends mammogram screening every 1 to 2 years for women age 40 and older.

In addition to Mammography, clinical breast exams (where the clinician palpates with the fingers) and breast self-examinations are important for Breast cancer screening. Women age 20 and older should receive clinical beast exams every 3 years; women age 40 and older should receive clinical breast exams every year. The American Cancer Society recommends that all women age 20 and older perform monthly breast self-examination.

These are general recommendations for Mammography, clinical breast exams, and breast self-exam. Women should discuss with their personal physician how often to receive Breast cancer screening, including Mammography and clinical breast exam. Recommendations vary depending on personal risk factors such a strong family history of Breast cancer.

Normal Values

Breast tissue that shows no evidence of mass (aggregations of cells) or calcification is considered normal.

What abnormal results mean

A well-outlined, regular, clear spot is more likely to be a benign lesion, such as a cyst (non-cancerous).

A poorly outlined, opaque area is more likely to suggest Breast cancer. However, not all benign lesions are perfectly round, and some cancers may appear well-defined. Sometimes, the doctor will use ultrasound to further examine the abnormality and evaluate the next best step. When findings from a mammogram or ultrasound look suspicious, a biopsy is performed to determine if a lesion is benign or cancerous.

Conditions under which the test may be performed include the following:

  • Breast cancer  
  • Breast infection  
  • Fibrocystic breast disease  
  • Lumps in the breasts  
  • Breast pain  
  • Nipple discharge

What the risks are

The level of radiation is low and any risk from Mammography is exceedingly low. If you are pregnant and need to have an abnormality checked, the abdominal area will be shielded by a lead apron.

Special considerations

Mammography is important because it can, in some cases, detect Breast cancers before you can feel them with your fingers.

Johns Hopkins patient information

Last revised: December 7, 2012
by Mamikon Bozoyan, M.D.

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