Patient education: Mammogram (The Basics)

What is a mammogram? — A mammogram is a special type of X-ray that creates pictures of your breast tissue.

A mammogram can be used:

●For breast cancer screening – This is a way that doctors check for early signs of cancer in people who have no symptoms of breast cancer. The goal of screening is to find cancer early, before it has a chance to grow and spread.

●To check for possible breast cancer – A mammogram can check for cancer in people who do have symptoms, such as a breast lump. This is called a "diagnostic" mammogram. It can also be done to get more detailed pictures if a screening mammogram shows anything abnormal.

How do I prepare for a mammogram? — Your doctor or nurse will tell you if you need to do anything special to prepare. When scheduling your mammogram, you might consider avoiding the time right before or during your period, if possible. Some people find that their breasts are sensitive during this time, and a mammogram might be more uncomfortable.

The staff where you are getting your mammogram will ask you about your "health history." This involves asking you questions about any health problems you have or had in the past, your family medical history, past surgeries, and any medicines you take.

On the day of your appointment, avoid using underarm deodorant, powder, or lotion. These can all have tiny amounts of metals. The metals can show up as spots on the mammogram and make it difficult to read.

What happens during a mammogram? — When it is time for your mammogram:

●You will undress from the waist up and put on a hospital cape or gown.

●A nurse or technician will help you get into the right position. The mammogram machine will flatten each breast between 2 panels. This can be uncomfortable, but it does not last long.

●Your breasts will be X-rayed 1 at a time. After each X-ray, the nurse or technician will help you adjust your position. For most screening mammograms, each breast will be X-rayed twice: once from the top down, and once from side to side. This lets the radiologist (the doctor who will look at your X-rays) get a good look at all of the tissue. In some cases, more angles are needed.

There are different types of machines used for mammograms. They include film mammography, digital mammography, and something called "digital breast tomosynthesis" ("DBT"). DBT creates images of the breast from different perspectives. It is sometimes called "3-D mammography."

●Sometimes, you might get another type of imaging test called an "ultrasound" during the same visit (figure 1).

What happens after a mammogram? — If a radiologist can look at your mammogram right away, you might get the results the same day. If not, you should get a phone call, letter, or other notification with your results within 30 days. If you use an online "patient portal," you might get an alert there when your results are ready.

If you do not hear back about your results, call the office or hospital where you had your mammogram, or your doctor's office. Do not assume that your mammogram was normal if you hear nothing.

What if my mammogram is abnormal? — If your mammogram is abnormal, try not to panic. In 9 out of 10 cases, an abnormal screening mammogram turns out not to be breast cancer. But you will need more tests to find out what's going on.

These tests might include:

●Another mammogram in 6 months – Doctors usually recommend this if they think your abnormal result is not likely due to cancer. But this way, they can check again to be sure.

●More imaging tests – These might include a more detailed mammogram or another type of imaging test like an ultrasound or MRI. These tests can let your doctor get a better view of your breast tissue. Your doctor might recommend one of these tests if they think that your abnormal result could be cancer. They might also suggest an ultrasound or MRI if your breast tissue is very dense. Dense breasts are normal, but they can make a mammogram harder to read.

●Biopsy – For this test, a doctor will take a small sample of tissue, then look at it under a microscope to check for cancer. Biopsies are usually done by taking some tissue from the breast with a needle during an ultrasound. But in some cases, biopsies involve a small surgery. You might have some discomfort during a biopsy.

What are the risks of a mammogram? — Your doctor will talk to you about all of the possible risks, and answer your questions. Possible risks include:

●False positives – Mammograms sometimes give "false-positive" results. This means that they suggest that you might have cancer when you actually do not. This can lead to unneeded worry and more tests. False-positive results are more likely to happen in people younger than 50 than in older people.

●Finding cancer that would not have needed treatment – Sometimes, mammograms find cancer that would never have affected your health. This can be a problem because treating these cancers does not have any benefit, and can cause harm. For example, you could get surgery, radiation treatment, or chemotherapy to treat a cancer that never would have caused problems if it hadn't been found. There is no way to know which cancers found by screening will lead to problems, and which won't.

●Radiation exposure – Like all X-rays, mammograms expose you to some radiation. But studies show that the number of lives saved by finding cancer early greatly outweighs the very small risks that come from this radiation exposure.

More on this topic

Patient education: Breast cancer screening (The Basics)
Patient education: Breast cancer (The Basics)
Patient education: Cancer screening (The Basics)
Patient education: Common breast problems (The Basics)
Patient education: Breast biopsy (The Basics)
Patient education: Sentinel lymph node biopsy for breast cancer (The Basics)
Patient education: Breast ultrasound (The Basics)

Patient education: Breast cancer screening (Beyond the Basics)
Patient education: Breast cancer guide to diagnosis and treatment (Beyond the Basics)
Patient education: Factors that affect breast cancer risk in women (Beyond the Basics)
Patient education: Common breast problems (Beyond the Basics)