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Written by the doctors and editors at UpToDate
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What is a mammogram?
This is a special type of X-ray that creates pictures of the breast tissue.
A mammogram can be used:
●For breast cancer screening – This is a way doctors can 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. Your breasts might be 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 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, do not use 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?
●You will undress from the waist up, and put on a hospital cape or gown.
●A nurse or technologist will help you get into the right position. The mammogram machine will flatten each breast between 2 panels (figure 1). 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 technologist 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 the tissue. In some cases, more angles are needed.
There are different types of machines used for mammograms. The most common are digital mammography and “digital breast tomosynthesis” (“DBT”). DBT creates images of the breast from different perspectives. It is sometimes called “3-D mammography.”
●You might get another type of imaging test called a “breast ultrasound” during the same visit (figure 2).
What if I have breast implants?
If you had surgery to get breast implants, the recommendations for when to get a mammogram are the same. The process is also similar, but usually involves taking extra pictures. If you have implants, tell the staff when you schedule a mammogram.
Implants can make it harder to see cancer and other problems on a mammogram. They can also make it harder to flatten the breasts. The nurse or technologist will:
●Take extra X-rays from different angles
●Push the implant to the side for some of the X-rays
This might be uncomfortable. But it’s important to get good views of all the breast tissue around the implants.
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 about 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 your mammogram was normal if you hear nothing.
What if my 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 test like an ultrasound or MRI. These can give your doctor a better view of your breast tissue. Your doctor might recommend 1 of these tests if they think 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 – A doctor takes a small sample of breast tissue, and then looks at it under a microscope to check for cancer. Biopsies are usually done with a needle. 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 the possible risks, and answer your questions.
Possible risks include:
●False positives – Mammograms sometimes give “false-positive” results. This means they suggest 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.
●Radiation exposure – Like all X-rays, mammograms expose you to some radiation. But studies show the number of lives saved by finding cancer early greatly outweighs the very small risks that come from this radiation exposure.