A mammogram is an x-ray picture of the breasts. It is used to find tumors and to help tell the difference between non-cancerous (benign) and cancerous (malignant) disease.

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.

Digital mammography is a recent technique that allows the x-ray image of the breast to be viewed and manipulated on a computer screen. It improves accuracy a little bit, but is not yet performed everywhere.

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 and chest area.

Notify your health care provider and the radiologist if you are pregnant or breastfeeding.

When the breast is compressed, there may be some discomfort.

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. Experts recommend that certain women at high risk of breast cancer should also have a breast MRI along with their yearly mammogram. Ask your doctor if you need an MRI.

Guidelines from the American College of Physicians, however, debate whether women with a low risk for breast cancer should begin mammogram screening at age 40. The 2007 guidelines, instead, recommend that women in their 40s ask their doctor when they should begin having the test.

In addition to mammography, clinical breast exams (where the clinician palpates with the fingers) and monthly breast self-examinations are important for breast cancer screening. Women age 20 and older should receive clinical breast 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.

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

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

A poorly outlined, cloudy area is more likely to suggest breast cancer (a cancerous lesion). However, not all breast cancers are perfectly round, and some cancers may appear well-defined.

Sometimes, the doctor will use ultrasound to further examine the problem and determine the next best step. When findings from a mammogram or ultrasound look suspicious, a biopsy is performed to determine if it a cancerous or non-cancerous condition.

Conditions under which a biopsy may be performed include:

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

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.

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

Smith RA, Salsow D, Sawyer KA, et al. American Cancer Society guidelines for breast cancer screening: Update 2003. CA Cancer J Clin. 2003;53(3):141-169.

Saslow D, Boetes C, Burke W, et al. American Cancer Society guidelines for breast screening with MRI as an adjunct to mammography. CA Cancer J Clin. 2007 Mar-Apr;57(2):75-89.

Lehman CD, Gatsonis C, Kuhl CK, et al. MRI evaluation of the contralateral breast in women with recently iagnosed breast cancer. N Engl J Med. 2007 Mar 29;356(13):1295-303. Epub 2007 Mar 28.

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.