Cervical Screening

What is cervical screening?

Cervical screening is not a test for cancer. It is a method of preventing cancer by detecting and treating early abnormalities which, if left untreated, could lead to cancer in a woman’s cervix (the neck of the womb). The first stage in cervical screening is taking a sample using liquid based cytology (LBC).

A sample of cells is taken from the cervix for analysis. A doctor or nurse inserts an instrument (a speculum) to open the woman’s vagina and uses a spatula to sweep around the cervix. Most women consider the procedure to be only mildly uncomfortable.

Early detection and treatment can prevent 75 per cent of cancers developing but like other screening tests, it is not perfect. It may not always detect early cell changes that could lead to cancer.


What is LBC?

Liquid based cytology (LBC) is a new way of preparing cervical samples for examination in the laboratory. The sample is collected in a similar way to the conventional smear, using a special device which brushes cells from the neck of the womb. Rather than smearing the sample onto a microscope slide as happens with the conventional smear, the head of the brush, where the cells are lodged, is broken off into a small glass vial containing preservative fluid, or rinsed directly into the preservative fluid. The sample is sent to the laboratory where it is spun and treated to remove obscuring material, for example mucus or pus, and a random sample of the remaining cells is taken. A thin layer of the cells is deposited onto a slide. The slide is examined in the usual way under a microscope by a cytologist.

Possible future developments

Computer assisted detection of cervical abnormalities is a possibility for the future.

The HPV vaccination programme started in September 2008 with all 12- to 13-year-old and 17- to 18-year-old girls being offered the vaccine. A catch-up programme was also announced at this time with 13- to 18-year-old girls being offered the vaccine over the following two academic years.

An accelerated catch-up programme was announced in December 2008 so that all girls born on or after 1 September 1990 could be protected before the end of the academic year 2009/10.

For more information about the vaccine see www.nhs.uk/Conditions/HPV-vaccination.

It will be many years before the vaccination programme has an effect upon cervical cancer incidence so the programme is not planning any changes yet. Vaccinated women are advised to continue accepting their invitations for cervical screening as the vaccination will not prevent all types of cervical cancer.


What does the NHS Cervical Screening Programme do?

The programme aims to reduce the number of women who develop invasive cervical cancer (incidence) and the number of women who die from it (mortality). It does this by regularly screening all women at risk so that conditions which might otherwise develop into invasive cancer can be identified and treated.


Who is eligible for cervical screening?

All women between the ages of 25 and 64 are eligible for a free cervical screening test every three to five years.

In the light of evidence published in 20031 the NHS Cervical Screening Programme offers screening at different intervals depending on age. This means that women are provided with a more targeted and effective screening programme.

The screening intervals are:

Age group (years) Frequency of screening
25 First invitation
25 – 49 3 yearly
50 – 64 5 yearly
65+ Only screen those who have not been screened since age 50 or have had recent abnormal tests

The NHS call and recall system invites women who are registered with a GP. It also keeps track of any follow-up investigation, and, if all is well, recalls the woman for screening in three or five years time. It is therefore important that all women ensure their GP has their correct name and address details and inform them if these change.

Women who have not had a recent test may be offered one when they attend their GP or family planning clinic on another matter. Women should receive their first invitation for routine screening at 25.


Why are women under 25 not invited?

This is because changes in the young cervix are normal. If they were thought to be abnormal this could lead to unnecessary treatment which could have consequences for women’s childbearing.2 Any abnormal changes can be easily picked up and treated from the age of 25. Rarely, younger women experience symptoms such as unexpected bleeding or bleeding after intercourse. In this case they should see their GP for advice.

In June 2009 the Advisory Committee on Cervical Screening reviewed the policy of starting screening at age 25 and agreed unanimously there should be no change in the current policy.

A research paper, Sasieni P, Castañón A, Cuzick J. Effectiveness of cervical screening with age: population based case-control study of prospectively recorded data. BMJ 2009; 339:b2968, focusing on women screened under the age of 25 was published in the BMJ. It stated:

‘Cervical screening in women aged 20-24 is substantially less effective in preventing cancer (and in preventing advanced stage tumours) than is screening in older women’


Why are women over 65 not invited?

Women aged 65 and over are taken out of the call recall system unless they need ongoing surveillance or follow up. This is generally required if a woman has had an abnormal result in any of her three most recent tests or is recommended for early repeats owing to a previous abnormality.

Generally speaking, the natural history and progression of cervical cancer means it is highly unlikely that women of 65 and over will go on to develop the disease. Women aged 65 and over who have never had a test are entitled to one.

What about women who are not sexually active?

The NHS Cervical Screening Programme invites all women between the ages of 25 and 64 for cervical screening. But if a woman has never been sexually active, then the research evidence shows that her chance of developing cervical cancer is very low indeed. We do not say no risk, only very low risk. In these circumstances, a woman might choose to decline the invitation for cervical screening on this occasion. If a woman is not currently sexually active but has been in the past, then we would recommend that she continues screening.


When was the NHS Cervical Screening Programme set up?

Cervical screening began in Britain in the mid-1960s. By the mid-1980s, although many women were having regular smear tests, there was concern that those at greatest risk were not being tested, and that those who had positive results were not being followed up and treated effectively.

The NHS Cervical Screening Programme was set up in 1988 when the Department of Health instructed all health authorities to introduce computerised call-recall systems and to meet certain quality standards.


How many women are screened?

The programme screens over three million women in England each year. Of the women in the target age group most were tested following an invitation and the rest were screened opportunistically at the suggestion of the sample taker or of the woman herself. For clinical reasons some women have more than one test during the course of a year, and 3.7 million samples were examined by pathology laboratories in 2010-2011.

Click here for the latest statistics on the NHS Cervical Screening Programme.


How is the programme organised?

More than 100,000 people are involved in cervical screening. They include the doctors and nurses who take the samples in GP surgeries and community clinics, the laboratory staff who review them and the people who run the computer systems.

The national office of the NHS Cancer Screening Programmes, based in Sheffield, is responsible for improving the overall performance of the programme. Set up in 1994, its priorities are to:

  • develop systems and guidelines which will assure a high quality of cervical screening throughout the country
  • identify important policy issues and help resolve them, and improve communications within the programme and to women

Every Primary Care Trust (PCT) has a nominated person responsible for its cervical screening programme and implementing the national guidelines.

Regional directors of public health are responsible for the quality assurance network in their region.


How much does the programme cost and how is it funded?

Cervical screening – including the cost of treating cervical abnormalities – has been estimated to cost around £157 million a year in England.

Primary Care Trusts commission cervical screening from the overall allocation they receive from the Department of Health.


Is cervical screening effective?

Whilst cervical screening cannot be 100 per cent effective, cervical screening programmes have been shown to reduce the incidence of cancer in a population of women. For example:

Percentage of Cancer Preventable

(Protection offered by a single negative smear)

20-39 years 40-54 years 55-69 years
3-yearly screening 41% 69% 73%
5-yearly screening 30% 63% 73%
Sasieni, Adams, and Cuzick, BJC 2003


Coverage of the target population

The effectiveness of the programme can also be judged by coverage. This is the percentage of women in the target age group (25 to 64) who have been screened in the last five years. If overall coverage of 80 per cent can be achieved, the evidence suggests that a reduction in death rates of around 95 per cent is possible in the long term. In 2010/11 the coverage of eligible women was 78.6 per cent3

[1] P Sasieni, J Adams and J Cuzick, Benefits of cervical screening at different ages: evidence from the UK audit of screening histories, British Journal of Cancer, July 2003
[2] Perinatal mortality and other severe adverse pregnancy outcomes associated with treatment of cervical intraepithelial neoplasia: meta-analysis. Arbyn M, Kyrgiou M, Simoens C, Raifu AO, Koliopoulos G, Martin-Hirsch P, Prendiville W, Paraskevaidis E. BMJ. 2008 Sep 18;337:a1284. doi: 10.1136/bmj.a1284. Review.
[3] Cervical Screening Programme, England: 2010-2011