Animation - how a mammogram is carried out

About mammography

Mammography is a technique used to take X-ray images of your breasts. The X-ray images are called mammograms.

You may have a mammogram if you’re invited for breast screening or because you have breast symptoms. If you have breast symptoms, it’s called a diagnostic mammogram. If you have no breast symptoms, it’s called a screening mammogram.

Screening mammography

Women over 50 are invited for screening by mammography every three years as part of the NHS Breast Screening Programme in England. The programme is being extended to women aged 47 to 50, but it won’t be phased in everywhere until 2016. A screening mammography is carried out at a breast cancer screening unit, which may be at a hospital, clinic or in a mobile unit. You can also have a screening mammography at an independent facility.

Diagnostic mammography

Diagnostic mammography is carried out at a special breast assessment clinic, usually based in a hospital. You may be referred for a diagnostic mammography if a routine screening mammography shows up any breast changes, if you or your GP have found a change in your breasts, or if you have noticed any breast symptoms.

What are the alternatives to mammography?

Mammography is the best way of detecting early breast cancer. However, ultrasound can also help to detect early breast cancer and is often used in women under 40, especially those who are pregnant or breastfeeding to avoid the risk involved in having an X-ray. Ultrasound uses sound waves to produce an image of the inside your breasts.

Preparing for your mammography

Don’t use any spray-on deodorant, talcum powder, antiperspirant or perfume on your breasts on the day of your mammography, as this could affect your mammogram.

Your radiographer (a health professional trained to perform imaging procedures) will explain the procedure and ensure that you’re happy to go ahead with the test.

If you’re pregnant, or think you might be, let your radiographer know. The radiation from the X-ray may affect your unborn baby. If you decide to go ahead with the mammogram, you will be given a lead apron to wear. This will cover your lower abdomen (tummy) and protect your unborn baby from any radiation. Alternatively, you may be able to have an ultrasound.

You should also let your radiographer know if you have breast implants. If you have implants, the procedure may be adapted slightly so that as much of your breast tissue as possible is shown on the mammogram.

You will need to undress to your waist. In a private cubicle, you will usually be asked to remove your clothing and put on a hospital gown.

What happens during a mammogram

The mammography will usually take 10 to 15 minutes. Most of this time is spent getting into position and preparing the equipment – the actual exposure to X-rays takes a few seconds.

Mammograms are taken using an X-ray machine called a mammography unit. You will be asked to place your breasts on a flat plate on the mammography unit, one at a time. There will be another flat plate above your breast. The plate above your breast will move down and your breast will be pressed in between the two plates to keep it still and allow a clear image to be taken. You may find the compression uncomfortable or painful.

Your radiographer will operate the X-ray machine from behind a screen, but will be able to see and hear you at all times. 


For a screening mammography, two mammograms are usually taken of each breast, one from above and one from the side. If you're having a diagnostic mammogram, you may have extra mammograms taken at different angles and magnification to get more detailed images. You will be asked to stay still while each mammogram is taken. 

You will be able to get dressed immediately after having a mammography. You will usually be able to go home when you feel ready.

Getting your results

Two radiologists (doctors who specialise in using imaging methods to diagnose medical conditions) will examine your mammograms for any signs of breast cancer.

You may be given your results on the same day as the mammography, or at the clinic at a later date, by post, or by your GP. You may want to have a close friend or relative with you for support when you get your results.

What to expect after a screening mammography

If there are any abnormal signs on your mammogram, you will be asked to attend a breast assessment clinic for further tests. Around five in 100 women in the UK are called back for further tests after having a screening mammography. If you’re called back, try not to worry. Only around 12 to 13 in 100 of those who are called back are found to have breast cancer.

What to expect after a diagnostic mammography

Your mammography results may show that there isn’t a problem with your breasts. This sometimes happens if you have been referred to the breast clinic because of signs of an abnormality on a screening mammogram. In this case, the screening mammogram is said to have a false positive result. If this happens, you won’t need any further tests.

Most false positive results are caused by a build-up of calcium in the milk ducts of your breasts (known as microcalcification). This is common in women over 50.

If your mammography results show signs of a breast abnormality, you will usually have other tests to help diagnose your breast condition. These may include a physical examination, an ultrasound scan and a breast biopsy.

Your test results may show that you have a benign (non-cancerous) breast condition, such as a cyst. If you have a benign condition, you may be referred to a breast care specialist for monitoring or treatment.

If your test results show that you have breast cancer, you will be referred to a doctor who specialises in cancer care (an oncologist) or a surgeon at a cancer treatment hospital.

What are the risks?

As with every procedure, there are some risks associated with mammography. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your radiographer to explain how these risks apply to you.

Mammography exposes you to a small amount of radiation. However, this is around the same as the radiation you’re exposed to naturally from the environment over a few months to a year, and is considered to be relatively safe. The dose given out by mammography is constantly monitored to reduce the potentially harmful effects of radiation.

It’s important to remember that although mammography is the best way of detecting early breast cancer, it isn’t a perfect test. Sometimes signs of breast cancer can be missed, despite the test being done correctly.

Sometimes, a screening mammography can show possible signs of breast cancer when in fact there is no problem. If this happens, you will be asked to have further tests, which may cause unnecessary worry.

I have breast implants. Will this affect the mammography?


Yes, mammography may be less effective if you have silicone breast implants. There are a number of things your radiographer can do to help make the results more accurate. 


Breast implants can affect your mammography results in a number of ways. Implants can hide some of your breast tissue, which can make it difficult to take a full view of all your breast tissue accurately on the mammogram. It’s common for calcium salt deposits to build up in the tissue around your implants. These deposits show up as small, white dots on the mammogram and can interfere with the interpretation of the results.

If you have breast implants, it’s important to let your radiographer know. If possible, tell the screening unit staff when you receive your invitation so that your mammography can be arranged at a breast clinic.

During the mammography, your breast is placed between two special plates on the X-ray machine. This shouldn’t damage your implants. Your radiographer will adapt the normal screening technique and take extra X-rays to show as much breast tissue as possible on the mammogram.

You should remember that mammography screens for breast cancer and doesn’t check on your implants.

Does everyone who is referred to a breast assessment clinic have a mammogram?


No, some women will have an ultrasound scan of their breast at the breast assessment clinic, instead of mammogram. 


At the breast assessment clinic, your breasts will be examined with either mammography or ultrasound scan. A mammography is an X-ray of your breasts and an ultrasound uses sound waves to produce an image of the inside your breasts.

An ultrasound scan is often used in women under 40, especially women who are pregnant or breastfeeding to avoid the risk of having an X-ray. Also, breast tissue in younger women is usually quite dense, so any abnormalities or breast changes may not show up on a mammogram. Ultrasound is also useful in all age groups when a lump can be felt in the breast.

If you have an ultrasound scan, an ultrasound specialist will put some gel onto your breast and then rub a special device over your breast area. You shouldn’t feel any pain during the procedure and it should only take around five to 10 minutes.

Can I bring someone with me to my mammography?


Yes, you can bring a friend or relative with you, but they may not be allowed to come with you into the X-ray room for your mammography. 


It can help to have a friend or relative with you when you go to the breast assessment clinic for tests and also when you get your results.

However, your friend or relative may not be able to accompany you into the X-ray room for your mammography. This is because of the radiation risk. There may also be some other areas of the breast assessment clinic that your friend or relative can’t accompany you to, as only people having tests will be allowed in.