A cervical screening test, or smear test, is a method of detecting abnormal (pre-cancerous) cells in the cervix in order to prevent cervical cancer. The cervix is the entrance to the womb from the vagina.
Cervical screening is not a test for cancer; it is a test to check the health of the cells of the cervix. Most women's test results show that everything is normal, but for 1 in 20 women the test will show some abnormal changes in the cells of the cervix.
Most of these changes will not lead to cervical cancer and the cells may go back to normal on their own. However, in some cases, the abnormal cells need to be treated to prevent them becoming cancerous.
The screening programme
About 2,900 cases of cervical cancer are diagnosed each year in the UK. This amounts to 2% of all cancer cases diagnosed in women.
The highest incidence of cervical cancer occurs in women aged between 30 and 39, with the under-35s most likely to be affected.
The number of women affected by cervical cancer falls steadily after the age of 40, although there is a slight increase in women who are over 70.
The aim of the NHS Cervical Screening Programme is to reduce the number of women who develop cervical cancer and the number of women who die from the disease. Since the screening programme was introduced in the 1980s, the number of cervical cancer cases has decreased by about 7% each year.
All women aged between 25 and 64 are invited for cervical screening. Women aged between 25 and 49 are invited for testing every three years, and women older than this are invited every five years.
Being screened regularly means that any abnormal changes in the cells of the cervix can be identified at an early stage and treated to stop cancer developing.
It is estimated that early detection and treatment can prevent up to 75% of cervical cancers.
Read more about why cervical screening is needed.
The screening test
The cervical screening test usually takes around five minutes to carry out. An instrument called a speculum will be gently inserted into your vagina to hold the walls of your vagina open so that your cervix is visible. A small brush-like instrument will be used to take some cells from the surface of your cervix.
The sample of cervical cells will then be sent to a laboratory and examined under a microscope to see whether there are any abnormal cells.
Test reliability
As with all screening tests, cervical screening is not 100% accurate. Regular screening can stop up to 75% of cancers from developing, but it does not prevent every case.
The procedure has recently been improved to eliminate mistakes. All cell samples are now examined by two fully trained technicians to ensure that any abnormal cells are identified and treated before cancer develops.
It's important that you do all you can to prevent cervical cancer from developing. This involves attending all cervical screening tests that you are invited to and making sure that you get your results.
You can read more information about how the cervical screening test is performed.
Human Papilloma Virus testing
Changes in the cells of the cervix are often caused by the Human Papilloma Virus (HPV), which also causes genital warts. There are more than 100 different types of HPV. Some types are high risk and some types are low risk. HPV-16 and HPV-18 are considered to be high risk for cervical cancer. Read more about what HPV is.
Following several years of trials, since April 2011 HPV testing has been incorporated into the NHS Cervical Screening Programme. This means that the cervical screening programme will be more efficient and accurate because it will help identify women with borderline or low-grade cervical abnormalities and enable the appropriate treatment to be given. This, in turn, will help to reduce unnecessary procedures and the anxiety that they may cause for many women.
Read more about the results of cervical screening tests.
