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Cervical cancer screening

Cervical screening is very important because we can stop cervical cancer from developing. This is one of the few cancers that is preventable because abnormal cell changes can be picked up before they have a chance to develop into cancer.

The screening test involves a nurse or doctor taking a small sample of cells from the surface of your cervix. They do this by putting an instrument called a speculum inside your vagina and then scraping the cervix with a small soft brush. The doctor or nurse rinses the brush in a pot of liquid, or removes the head of the brush and leaves it in the liquid. They then send the sample to the laboratory.

Who is screened?

If you are between the ages of 25 and 64, the NHS cervical screening programme will contact you every 3 to 5 years (depending on your age) and ask you to go for a cervical screening test. At the moment, the age that screening starts and finishes is slightly different in Scotland. But they plan on changing their screening ages to be in line with the rest of the UK in 2015.

Screening test results

The screening test picks up abnormal cell changes. This does NOT mean that you have cervical cancer. But if these abnormal cells were left untreated they may develop into cervical cancer in the future.

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What is cervical cancer screening

Cancer screening involves testing apparently healthy people for signs that could indicate cancer is starting to develop. 

Cervical screening is a way of preventing cancer by finding and treating early changes that could lead to cancer in the neck of the womb (cervix) if left untreated. It uses a test called cytology which many people know as the smear test. A nurse or doctor takes a sample of cells from the cervix with a small brush. The cells are sent to a laboratory to be tested for abnormalities.


Who has cervical screening

In England, Northern Ireland and Wales, the NHS cervical screening programme invites women from ages 25 to 64 for cervical screening. Women aged 25 to 49 are invited every 3 years. After that, women are invited every 5 years until the age of 64.

In Scotland, women aged 20 to 60 are invited for screening every 3 years. But in 2015, this will change to follow the same screening schedule as England, Northern Ireland and Wales.

We know from research that cervical cancer is very rare before the age of 25. But changes in the cervix are quite common in younger women. So, screening younger women can lead to unnecessary treatment and worry. Following recommendations from the UK National Screening Committee in 2012, Scotland plans to raise the screening age to 25. They will also extend screening for women up to the age of 64. 


Tests used in cervical screening

The screening test involves taking a sample of cells from the surface of the cervix. It is called liquid based cytology (LBC).

Taking a sample of cells

To have the test you take off your underwear and lie on your back on a couch. You need to lie with your knees drawn up and spread apart. If this position is difficult for you, you can ask your nurse to take the test when you are lying on your side with your knees drawn up.

To take the sample of cells, the doctor or nurse puts an instrument called a speculum inside your vagina so that they can see the cervix clearly. Having the speculum put in may be a little uncomfortable but it shouldn't hurt. It can be more uncomfortable if you are very tense. Try to relax. Taking a few deep breaths can help. 

The doctor or nurse gently scrapes the surface of your cervix with a small soft brush. This collects a sample of cells from the outer layer of the cervix. They put the sample into a pot of liquid and send it to the laboratory. Then they gently remove the speculum and the test is over. You can get down from the couch.

In the laboratory, a pathologist puts the sample under a microscope. They examine the cells and report any abnormal ones. If your result shows mild changes the laboratory tests your sample for human papilloma virus (HPV).

Human papilloma virus testing

Human papilloma virus is a very common virus. It can be passed from person to person during intimate sexual contact. Most women have it at some point in their lives, and in most cases your body will get rid of the virus without you ever knowing you had it. HPV is linked to the development of abnormal cervical cells. If HPV is found in the sample you will be invited to go for a test called colposcopy. Colposcopy looks very closely at the cervix using a specialised magnifying instrument called a colposcope.


After the test

The laboratory sends the results of your test back to your GP surgery. They will send you a letter telling you the result. Usually you get the result within 2 weeks.

In some areas, if you have an abnormal result you will get a letter directly from the hospital. The letter will include an appointment for the colposcopy clinic if necessary. The letter will usually include a small booklet to explain more about what an abnormal result means.


What the results mean

There are several different results you can have after a screening test. Many women have a normal result.

Some of the results are due to problems with the test rather than because there are any abnormal cells. 

You could be told that you need a repeat test because yours could not be read properly. This is sometimes called having an inadequate sample. This could be because

  • There were not enough cells in the sample
  • You have an infection which meant the cells could not be seen clearly enough
  • You were having a period and there is too much blood to see the cells clearly
  • The cervix was inflamed and so the cells could not be seen clearly enough

In all these cases, you will get a letter asking you to go back and have another test. This is usually about 3 months later.

If you have an abnormal result

Although most women have normal results, it's not uncommon to have an abnormal result. This happens in around 1 in 20 women (5%). 

An abnormal result means that there are some changes to the cells on the cervix. These changes are not cancer. Many of the changes will go back to normal by themselves. But in some cases, if left untreated, these changes could develop into cancer in the future. 

Abnormal results can be reported in 2 different ways. You are most likely to be told you have

  • Borderline or mild cell changes (low grade dyskaryosis)
  • Moderate or severe cell changes (high grade dyskaryosis)

More rarely your screening test result may say CIN 1, CIN 2, or CIN 3 instead of mild, moderate or severe. CIN stands for cervical intraepithelial neoplasia and is not cancer. This classification is not strictly accurate as CIN can only really be diagnosed with a biopsy. The 3 grades of CIN relate to the thickness of the skin covering the cervix that is affected. 

  • CIN 1 means up to one third of the thickness of the skin covering the cervix has abnormal cells
  • CIN 2 means between one third and two thirds of the skin covering the cervix has abnormal cells
  • CIN 3 means the full thickness of the skin covering the cervix has abnormal cells. 

Both the level of cell abnormality (mild, moderate or severe) and the CIN level will be taken into account when deciding whether you need treatment.

It is very rare for an abnormal result to show that a cancer has already developed, especially if you have been having regular screening. But this is possible.

If you have a cervical erosion

Cervical erosion is a condition often picked up by cervical screening tests. You may hear it called an ectropion. It has nothing to do with cervical cancer. It means that glandular cells, which are only normally seen inside the cervical canal, can be seen on the surface of the cervix. The cervix often looks a little inflamed in this area. 

An erosion will not harm you. It is common in teenagers, in pregnancy, and in women on the pill. It can cause slight bleeding, especially after sex. Usually the condition goes away by itself without any treatment.


If you have mild cell changes

Currently, what happens if you have borderline or mild cell changes (low grade dyskaryosis) varies depending on where you live.

In England and Northern Ireland

If you have borderline or mild cell changes, the laboratory will test your sample for the human papilloma virus (HPV). Certain types of this virus increase the risk of cervical cancer. If there is no HPV (HPV negative), the cell changes are likely to go back to normal or stay the same. So you will go back to the routine screening programme of having tests every 3 to 5 years.

If you have a high risk type of HPV, you will be invited for colposcopy to see if you need treatment for the abnormal cells.

You can read about treatment for abnormal cervical cells.

In Scotland and Wales

In Scotland or Wales, your doctor or nurse will either suggest a colposcopy straight away or ask you to go back for another screening test in 6 months time. Sometimes these slightly abnormal cells can go back to normal by themselves. If your next test is normal you may have 2 further tests, 6 months apart, before going back to regular screening every 3 to 5 years. If your repeat test is abnormal, you will then have a colposcopy to check it out further. You may then need some treatment.


If you have moderate or severe cell changes

If you have moderate or severe cell changes (high grade dyskaryosis), you will be referred for colposcopy straight away. Your doctor or specialist nurse will take a sample of cells (biopsy) from the abnormal area. They may ask you to go back for treatment depending on the result of the biopsy. Or in some clinics, they may offer you treatment at the same time as the colposcopy. 

You can read our information about treatment for abnormal cervical cells.

You usually only need treatment once. Then you have follow up tests. If you have an abnormal test and have successful treatment you are very unlikely to get cervical cancer if you continue having screening. If you do not have treatment, you are very much at risk of developing cervical cancer in the future.


Carcinoma in situ (CIS)

CIN 3 is sometimes called carcinoma in situ. This sounds like cancer, but it isn't. It means that some of the cells look cancerous. But they are all contained within the skin layer covering the cervix. It is not be a true cancer until the cells break through the layer covering the cervix and spread into the tissue underneath. You must have treatment as soon as possible if you have carcinoma in situ. As long as the affected area is removed, cancer can be prevented.


Benefits of cervical screening

Scientists estimate that cervical screening saves around 5000 lives each year in the UK.

Cervical screening can prevent at least

  • 75% of cervical cancers in women in their 50s and 60s
  • 60% of cervical cancers in women in their 40s
  • 45% of cervical cancers in women in their 30s

Since the introduction of cervical screening in the 1980s, rates of cervical cancer have almost halved.


Possible harms of cervical screening

Cervical screening works very well but, like any screening test, it isn’t perfect. In a very few cases tests will find abnormal changes that aren’t really there and this is called a false positive result. This leads to unnecessary worry for the woman and also the need for more tests.

1 in 5 tests will also miss cell changes. This is called a false negative result. 

Sometimes it is difficult to tell whether changes in the cervix will go back to normal or develop into cancer after some years. So, some women will have treatment unnecessarily for changes that would not have caused any harm if they had been left alone. This is called overdiagnosis or overtreatment. It is hard to know exactly how often women may be overdiagnosed or overtreated in this way. But the benefits of preventing cervical cancers are so great that they very much outweigh the harms of some unnecessary treatment in women from their early 20s to mid 60s.


Staying healthy

Since 2008, girls aged 12 and 13 have been offered a vaccination against the human papillomavirus (HPV). This vaccine can prevent over 70% of cervical cancers. It is important for girls to have the vaccination when it is offered at school. But there are many types of HPV linked to cervical cancer. Although the vaccine protects against the two types that cause most cases of cervical cancer, it doesn't protect against all of them. This means that screening will still benefit girls who have been vaccinated.

As well as attending for screening when you are invited, it is still important to keep an eye out for any unusual changes in your body. If you notice anything unusual, make an appointment to see your doctor and get it checked out.

Smoking can increase the risk of cervical cancer. This is because cancer causing chemicals in cigarette smoke can go into the blood and travel around the body. These chemicals can damage the cells of the cervix. 

You can get advice on giving up smoking.


Related information

The current cervical screening programme works very well. But new tests may prove to be even better. Researchers are looking at new ways of using the HPV test as part of the screening programme. You can read more about research into cervical cancer screening on our page about cervical cancer research.

You can also find cervical cancer screening trials on our clinical trials database.

There is information about the cervical screening programme in different languages on the NHS cervical screening programme website.

Our CancerStats section has detailed statistical information about cervical screening.

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Updated: 25 November 2014