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What is a mammogram?

A mammogram is an X-ray image of your breast. It is used to find and diagnose breast disease in women. Your healthcare provider may order a mammogram if you have a breast problem such as a lump, pain, or discharge from a nipple. Your provider may also order one as a screening test. The test can look for breast cancers, noncancerous or benign tumors, and cysts before they can be felt.

If a mammogram shows an area in your breast that may be cancer, your provider can remove a sample of tissue. This is called a biopsy. Your provider may remove the tissue by needle or during surgery. The tissue will be looked at under a microscope to find out if it is cancer.

X-rays use a small amount of radiation to create images of your bones and internal organs. X-rays are most often used to find bone or joint problems, or to check the heart and lungs. Mammograms are one type of X-ray.

Mammograms may also be done with the help of a computer to make digital images. This method is good for women younger than 50, women with dense breast tissue, and women who are premenopausal or perimenopausal. Digital mammograms are basically done the same way as a standard mammogram.

With either method, the mammogram images are checked for masses, tiny mineral deposits called calcifications, or areas of abnormal density. Any of these may mean that you have cancer. The problem areas are highlighted by the computer for a radiologist to look at.

Why might I need a mammogram?

You may need a mammogram as a screening test or to help your healthcare provider make a diagnosis. If you are older than 25, you should have a mammogram if you have these symptoms:

  • A lump
  • Thickened skin on your breast
  • Skin indentation on your breast
  • A nipple with leaking fluid, or discharge
  • A sore on a nipple that doesn’t get better
  • Breast pain
You may also need a screening mammogram if you have breasts that are dense, lumpy, or very large. This is because your provider may not be able to do a full physical breast exam.

You may also need a routine mammogram if you are at high risk for breast cancer. Or if you have had breast cancer in the past.

Your provider may have other reasons for recommending that you have a mammogram.

When to get a mammogram

Different health experts have different recommendations for women who have no symptoms of breast cancer:

  • The U.S. Preventive Services Task Force recommends screening every 2 years for women ages 50 to 74.
  • The American Cancer Society recommends screening be an option for women who are at average risk, starting at age 40. Mammograms should be done every year for all women ages 45 to 54. Then you can switch to mammograms every 2 years. Or you have the choice to continue annual mammograms.

Talk with your healthcare provider to find out which screening guidelines are right for you. If you are at higher risk for breast cancer, talk with your provider about:

  • Starting screening mammograms earlier
  • Having additional tests such as breast ultrasound or MRI
  • Having mammograms more often

What are the risks of a mammogram?

A mammogram is done with X-rays, which use a small amount of radiation. Talk with your healthcare provider about the amount of radiation used and any risks that apply to you.

Consider writing down all X-rays you get. This includes past scans and X-rays for other health reasons. Show this list to your provider. The risks of radiation exposure may be linked to the number of X-rays you have and the X-ray treatments you have over time.

Tell your provider if you are pregnant or think you may be pregnant. Radiation exposure during pregnancy may lead to birth defects. If you need to have a mammogram while you are pregnant, your provider will take special steps to keep radiation exposure to your baby as low as possible.

Mammograms may be harder to interpret if you are younger than 30. This is because your breast tissue is denser than when you are older.

You may feel some pain or discomfort during the mammogram because your breast is compressed against the X-ray plate. This pressure will not harm your breast.

You may have other risks depending on your specific health condition. Be sure to talk with your provider about any concerns you have before the test.

Some things may make your mammogram less accurate. They include:

  • Powder, deodorant, creams, or lotions that you put on your underarms or on your breasts
  • Breast implants. If you have breast implants, be sure to tell your mammography facility that you have them when you make your appointment. You will need an X-ray technologist who is trained in working with women with implants. This is important because breast implants can hide some breast tissue. This can make it hard for the radiologist to see breast cancer if it is there.
  • Past breast surgery
  • Hormonal breast changes

How do I get ready for a mammogram?

  • Your healthcare provider will explain the procedure to you. Ask him or her any questions you have.
  • You may be asked to sign a consent form that gives permission to do the procedure. Read the form carefully and ask questions if anything is not clear.
  • You can eat and drink as normal before the procedure. You will not need any medicine to help you relax or go to sleep.
  • Tell your provider if you are pregnant or think you may be pregnant.
  • Tell your provider about all medicines you are taking. This includes prescriptions, over-the-counter medicines, and herbal supplements.
  • Tell your provider if you have breast implants or if you are breastfeeding.
  • Wear clothing that you can easily remove.
  • Ask if you need to bring past mammogram images with you. This is important if you have a mammogram done at a new facility. The radiologist will need to compare past images with the new ones.
  • Do not use deodorant, perfume, powders, or ointment on your breasts or in the underarm area on the day of the mammogram. These things may make it harder to get a clear image of your breasts.
  • If your breasts are painful, you may need to stop eating or drinking foods with caffeine for 5 to 7 days before your test.
  • Breasts are often tender the week before and during your period. Try to schedule your mammogram for 1 to 2 weeks after your period starts.
  • Follow any other instructions your provider gives you to get ready.

What happens during a mammogram?

You may have your mammogram done as an outpatient. Or it may be done as part of your stay in a hospital. The way the test is done may vary. It depends on your condition and your healthcare provider's practices.

Generally, a mammogram follows this process:

  1. You will be asked to remove any clothing, jewelry, or other objects that might get in the way of the test.
  2. You will be asked to remove clothing from your waist up. You will be given a gown to wear.
  3. The technologist will ask you if you have seen or felt any lumps or other changes in either breast. If so, the technologist will put a marker on that spot before the procedure.
  4. You will stand in front of a mammography machine. One breast will be put on the X-ray plate. The technologist may look at your breast or move your breast around to put it in the best place for the picture. He or she may put a marker on any moles, scars, or other spots that might affect the breast image.
  5. The technologist will move a flat plastic plate down on top of your breast. This will squeeze or compress your breast gently against the X-ray plate. This pressure is needed to keep the radiation level as low as possible. It also helps take the best picture of your breast tissue. You may feel some pain or discomfort during this time.
  6. You will be asked to hold your breath while the image is taken.
  7. The technologist will step behind a protective window while the image is taken.
  8. The technologist will take 2 pictures of each breast at different angles. He or she will need to reposition your breast between pictures.
  9. After the X-rays have been taken, you will be asked to wait. The radiologist will look at the images. He or she will make sure they are clear and that no more pictures are needed. You may need to have more pictures taken if the radiologist has any questions about the first set of images.
  10. The test takes about 20 to 30 minutes.

The mammogram itself is not painful. But you may feel discomfort or pain when your breast is moved around and compressed. This is especially true if you have had a recent breast injury or surgery. The technologist will use all possible comfort measures and complete the test as soon as possible.

What happens after a mammogram?

In most cases you will not need to do anything special after a mammogram. Your healthcare provider may give you additional instructions, depending on your situation.

Next steps

Before you agree to the test or the procedure make sure you know:
  • The name of the test or procedure
  • The reason you are having the test or procedure
  • The risks and benefits of the test or procedure
  • When and where you are to have the test or procedure and who will do it
  • When and how will you get the results
  • How much will you have to pay for the test or procedure
Online Medical Reviewer: Freeborn, Donna, PhD, CNM, FNP
Online Medical Reviewer: MMI board-certified, academically affiliated clinician
Date Last Reviewed: 11/17/2015
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