Cervical cancer screening

Cervical screening is very important because we can stop cervical cancer from developing in the first place. This is one of the few cancers that is preventable because pre cancerous cell changes can be picked up before they have a chance to develop into a cancer. Cervical cancer screening has been available in the UK since 1967.

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 brush. They put the brush and cells into a small pot of liquid and send it to the laboratory. This is called liquid based cytology. In the lab, your sample is put under a microscope. The cells are examined and any abnormal ones reported.

In the past, cells used to be collected from the cervix using a wooden spatula and the cells were spread onto a glass slide. This was called a cervical smear or PAP smear.

If you are between the ages of 25 and 60 in the UK, the NHS cervical screening programme will contact you every 3 to 5 years and ask you  to go for a cervical screening test. The exact age groups for screening vary between the different countries of the United Kingdom.

In England and Northern Ireland, women between 25 and 64 years are screened. 

In Scotland, women between 20 and 60 are invited for screening. 

In Wales, women between 20 and 64 are screened. 

There is information about why the screening age varies further down this page.

The screening interval is the time between the screening tests. This used to vary between health authorities. But research reported in 2003 by Cancer Research UK showed that the screening interval should be decided by age. We can pick up the most cancers by screening women every 3 years if they are 25 to 49 years old and every 5 years if they are between 50 and 64. 

For women between 25 and 49, 3 yearly screening prevents 84 cervical cancers out of every 100 that would develop without screening. 5 yearly screening will only prevent 73 cancers out of 100. So the guidelines now recommend screening women 3 yearly if they are under 50.

It is acceptable and safe for women of 50 or more to have 5 yearly smears. Screening 3 yearly doesn't give any extra protection for this age group. This is probably because abnormal cells develop more slowly in women over 49.

The NHS in England and Northern Ireland have adopted these recommendations. So if you are between 25 and 49 and live in England or Northern Ireland, your health authority will offer you 3 yearly cervical screening.

You can have a cervical screening test at

• Your GP surgery
• A well woman clinic
• A family planning clinic
• A genito urinary clinic (clinic for problems with the genital or urinary organs)
• An antenatal clinic if you are pregnant
• A private health clinic
• A voluntary organisation clinic, such as Marie Stopes

You can ask for a female nurse or doctor to do your cervical screening test. All clinics will have women available to chaperone a male doctor. But if you only want a woman to do the test, you may have to make an appointment to go back at a later date. So if you are concerned about this, it is best to mention it when you originally make your appointment.

Remember that you should try to make your screening appointment for the middle of your menstrual cycle. In other words, between periods. It is more difficult for your doctor or nurse to see the cervix and take a sample of cells if you have your period when you go. You may get an inadequate result and have to go back for another test.

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

The test may be a little uncomfortable because of the position you have to get into. It shouldn't hurt. It can be more uncomfortable if you are very tense. Try to relax. Taking a few deep breaths can help. Breathe in and out deeply through your mouth several times.

To take the sample of cells, the doctor or nurse puts an instrument called a speculum inside your vagina. The speculum has two arms that spread the sides of your vagina apart so that the doctor or nurse can see the cervix clearly. Then they scrape the surface of your cervix with a small brush. This collects a sample of cells from the outer layer of the cervix. As soon as the doctor or nurse takes the sample, they will put it into a pot of liquid, and send it to the laboratory. The test is then over and you can get down from the couch.

The NHS screening programme now uses liquid based cytology (LBC) to preserve the cells taken in cervical screening tests. The doctor or nurse collects the cells from the cervix using a very small brush. The head of the brush is broken off into a small pot of liquid, or the cells rinsed off into the pot, instead of putting the cells onto a slide, as used to be done with a PAP smear. The cells are preserved better with LBC, so the results of the test are more reliable.

The lab will automatically send the results back to the surgery or clinic where you had the test. Your surgery may not contact you if the test is normal. But they should if there is anything wrong. Or if the test could not be read properly for some reason. Just to make sure, it is best to contact your GP or clinic for your own result. Ask them when the results should be back. Then you can ring if you haven't heard.

There are several different results you can have after a screening test. Some of the results are due to problems with the test rather than because there are any abnormal cells. You could be told you need a repeat test because yours could not be read properly (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 just be asked to go back and have another test. This is usually about 3 months later. If you have an infection, you will be given some treatment first.

You may be told your test result was borderline. This means that cell changes were seen but that they were so near normal that they are probably nothing to worry about and will go back to normal on their own. As with mild changes you will need to go for a repeat test, probably in 6 months.

The NHS cervical cancer screening programme has begun to offer women with borderline and mild changes a test to check for the human papilloma virus (HPV). Women who test positive for high risk types of HPV are referred for a colposcopy straight away. In women who test negative for HPV the cell changes are likely to go back to normal on their own so they don't need treatment. And they will continue to have regular screening every 3 or 5 years depending on their age.

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 is nothing to worry about. 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.

Abnormal results can be reported in two different ways. In the UK, if you have abnormal cells you are most likely to be told you have

• Mild or slight cell changes (mild dyskaryosis)
• Moderate cell changes (moderate dyskaryosis)
• Severe cell changes (severe dyskaryosis)

More rarely your smear test result may say CIN 1, CIN 2, or CIN 3 instead of mild, moderate or severe. CIN stands for cervical intraepithelial neoplasia. This just means cervical cell changes. This classification is not strictly accurate as CIN can only really be diagnosed with a biopsy. But the smear results do indicate that you probably have

• CIN 1 if you have mild cell changes
• CIN 2 if you have moderate cell changes
• CIN 3 if you have severe cell changes

The three grades of CIN relate to the thickness of the skin covering the cervix that is affected. CIN 1 means one third of the thickness 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.

All these results mean that cells have been found on your test that are pre cancerous. This does not mean you have cervical cancer. It means that some of the cells are slightly abnormal and if they are left untreated, they could go on to develop into cervical cancer.

Remember that we are talking about the test as screening for cervical cancer here. Screening means testing healthy women. If you have symptoms of cervical cancer, you may be given a liquid based cytology test as part of the tests used to investigate your symptoms. This is a very different situation to having the test as a routine screening test.

If you have borderline or mild cell changes or CIN 1, your doctor or nurse will either suggest a colposcopy straight away or ask you to go back for another liquid based cytology test in 6 months time. Sometimes these slightly abnormal cells can go back to normal by themselves. But you should definitely go for your repeat test. You can't assume that the cells will go back to normal. If your next test is normal you may have 2 further tests, 6 months apart, before returning to regular screening every 3 to 5 years. If your test is abnormal, you will then definitely have a colposcopy to check it out further. You may need some treatment.

This guidance will change slightly as the NHS cervical cancer screening programme brings in HPV testing for borderline and mild test results. If the laboratory has tested your cell sample for HPV and it is negative, you will return to routine screening every 3 to 5 years. Women who have a high risk type of HPV will be invited for colposcopy to see if treatment is needed.

If you have moderate or severe cell changes, or CIN 2 or 3, you will be referred to colposcopy straight away. Your doctor or specialist nurse will take a sample of cells (biopsy) from the abnormal area. They may ask you to come 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. There is more about treatment for abnormal cervical cells in this section.

You usually only need treatment once. Then you have follow up tests. If you do have an abnormal test and have successful treatment you are very unlikely to get cervical cancer (provided you continue being screened). If you do not have treatment, you are very much at risk from cervical cancer.

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 will 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.

More than 9 out of 10 test results are normal (90%). About 1 in 20 shows borderline or mild cell changes (5%). In most of these women, the cells will go back to normal by themselves.

About 1 in 200 tests (0.5%) show moderate cell changes. And another 1 in 200 shows severe changes. These women will go on to have colposcopy to investigate further.

Less than 1 in 1,000 tests shows an invasive cancer. If you have an invasive cancer your doctor or nurse will refer you to a specialist very quickly.

You may have heard various news reports in the past about women being recalled for cervical screening tests because the system went wrong. And even about some women dying from cervical cancer because their tests were not checked properly and so they missed out on the treatment they needed. But this is very, very rare. As a result of these few mistakes, the screening system has been tightened up even further.

Now all the samples are examined in the laboratory by trained technicians looking down microscopes. Because people can make mistakes, two different people now check all cervical screening tests. The abnormal cells that were missed in the past were all in health authorities who didn't make sure two people checked their samples. And in some cases because technicians were not trained or supervised properly. So you can feel reassured that if there are abnormal cells in your screening test they are highly likely to be found and treated so that they cannot develop into a cancer.

Lastly, always make sure you get your result. If you do not get the result, there is always the tiny chance that the test was reported as abnormal but that this result was not sent back to you or your GP.

The original cervical cancer screening programmes across the UK screened women from 20 to 64. The screening programme in England and Northern Ireland now starts at 25 because cervical cancer is very rare before this age. But changes in the cervix are quite common in younger women. So screening younger women can lead to unnecessary treatment and worry.

There is still more evidence coming in about the exact age groups we should screen. Wales and Scotland are still screening from age 20 until more evidence comes in, including from their own screening programmes. Another complication is that liquid based cytology has been introduced over the last few years. If you make more than one major change at a time to any health programme, you won't necessarily know which change is responsible for improvements in your service. In Wales, for example, they decided to stick with the original screening age, and introduce LBC fully before making any more changes.

Make sure that you begin having regular cervical screening as soon as you are 25 if you are sexually active. If you are under 25 and are at all concerned, talk to your GP or go to a well woman clinic.

In England, Wales and Northern Ireland, the screening programme stops at 64. This is because women who have had normal cervical screening tests are very unlikely to go on to develop cervical cancer after this age. The NHS guidelines say that if your last 3 cervical screening tests were normal when you are 64, there is no need to have any more. But many older women have not had enough tests. The UK cervical screening programme has not cut the number of cases of cervical cancer as quickly as it hoped. One reason for this is because many older women have never had tests.

So, if you are over 64 and your last 3 tests were normal, you will not be asked to go to have any more. If you are over 64 and have had abnormal tests, you will continue to be invited for regular tests in the normal way. In Scotland, the screening programme stops at 60.

If you have never had a cervical screening test, you should have one done regardless of your age unless you have never been sexually active. Ask at your GP surgery or well woman clinic.

Remember that if you are over 64 and have not had 3 normal tests in a row, you should carry on having regular tests until you do. Make sure you ask at your GP or well woman clinic if you think you should continue to have regular screening tests.