A cervical screening test (previously known as a smear test) is a method of detecting abnormal cells on the cervix. The cervix is the entrance to the womb from the vagina.
Detecting and removing abnormal cervical cells can prevent cervical cancer.
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 around 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 removed so that they cannot become cancerous.
About 3,000 cases of cervical cancer are diagnosed each year in the UK, which amounts to 2% of all cancers diagnosed in women.
It's possible for women of all ages to develop cervical cancer, although the condition mainly affects sexually active women between the ages of 30 and 45. The condition is very rare in women under 25.
The cervical screening programme
The aim of the Cervical Screening Programme is to reduce the number of women who develop cervical cancer and the number of women who die from the condition. 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 aged between 50 and 64 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, if necessary, treated to stop cancer developing.
It is estimated that early detection and treatment can prevent up to 75% of cervical cancers.
The cervical 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 soft brush 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.
Some women may find the procedure a bit uncomfortable or embarrassing, but for most women it is not painful.
If the test picks up abnormalities in the cells in your cervix, it may be recommended that you have treatment to remove them, or further tests in a few months to see if they return to normal on their own.
You shouldn't have a cervical screening test during your period, so try to arrange an appointment before or after your period is due. The middle of your cycle is the best time to have the test (usually 14 days from the start of your last period).
Changes in the cells of the cervix are often caused by the human papilloma virus (HPV). 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.
If a sample taken during for cervical screening test shows low-grade or borderline cell abnormalities, the sample should automatically be tested for HPV. If HPV is found in your sample, you should be referred for a colposcopy for further investigation and, if necessary, treatment. If no HPV is found, then you will carry on being routinely screened as normal.
If your sample shows more significant cell changes you will be referred for colposcopy without HPV testing.
In some areas, a test for HPV will be carried out as the first test on the screening sample. In these cases, the sample will only be checked for abnormal cells if HPV is found. If HPV isn’t found, you will be offered a screening test again in three to five years time (depending on your age).
Why cervical screening is offered
Cervical screening is offered because it can help detect abnormal cell changes in the cervix (the lower part of the womb) that could potentially develop into cervical cancer.
Abnormal cells that are picked up during cervical screening often return to normal on their own, so your doctor may recommend waiting to see if they do.
However, if more significant abnormalities are detected at an early stage there is the option of having treatment to remove them before they have a chance to become cancerous.
Since the screening programme was introduced in the 1980s, the number of cervical cancer cases has decreased by about 7% each year and it's estimated that up to 4,000 cases of cervical cancer are prevented each year in the UK because of cervical screening.
What causes abnormal cell changes in the cervix?
Abnormal changes in the cells of the cervix can be caused by certain high-risk types of human papilloma virus (HPV).
HPV is the name of a family of common viruses that affect the skin and the mucus membranes (moist tissue that line parts of the body), such as those in your cervix, anus, mouth and throat.
HPV is very common. It's estimated that 8 out of 10 people in the UK are infected with HPV at some point during their lifetime. For most people, the virus goes away without treatment and does not cause any harm.
However, infection with some types of HPV can cause abnormal cell growth, which can lead to cervical cancer. Other forms of HPV cause genital warts.
HPV infection is passed on through skin-to-skin contact. The types of HPV that can cause abnormalities in the cells of your cervix are transmitted through sexual contact.
Can HPV be prevented?
It can be very difficult to prevent HPV, which is one of the reasons cervical screening is considered to be so important.
Using a condom during sex can help reduce your risk of developing an HPV infection, but as condoms do not cover the entire genital area and are often put on after sexual contact has begun, they are no guarantee against the spread of HPV.
This has been shown to provide effective protection against HPV for at least eight years, but it is not yet known how long protection lasts beyond this time.
How common are abnormal results?
For every 100 women who have cervical screening, about six will have an abnormal result.
It is very rare for cancer to be diagnosed from the results of a cervical screening test. Less than one in 1,000 test results show invasive cancer.
Are there any disadvantages of screening?
Although cervical screening can help prevent cervical cancer, there are some potential disadvantages associated with screening. These include:
potential discomfort, embarrassment or, less commonly, pain during the screening test
a very small chance of getting incorrect results, which could lead to abnormalities being missed or unnecessary distress and treatment
a chance of having unnecessary treatment if the abnormalities would have corrected themselves naturally
some treatments used to remove abnormal cells may increase your risk of giving birth prematurely (before the 37th week of pregnancy) if you get pregnant in the future
However, cervical screening is offered to women aged 25-64 in England because the potential benefits of screening are believed to outweigh these risks.
When cervical screening is offered
This includes women who have had the HPV vaccination, as the vaccine does not guarantee complete protection against cervical cancer.
Women should normally be invited for cervical screening at the following times:
by the age of 25 you will receive your first invitation for screening
when you are 25 to 49 years old you are invited for screening every three years
when you are 50 to 64 years old you are invited for screening every five years
when you are aged 65 or over you are only screened if you have not been screened since you were 50 or if you have had recent abnormal test results
If you have not had a cervical screening test within the appropriate time, you may be offered one when you next visit your GP or family planning clinic. You can also contact your GP practice to book a screening appointment if you are overdue one.
Make sure that your GP has your correct name and address and let them know of any changes so you can be contacted when you are due to have a screening test.
If you are not registered with a GP practice, or if you don’t wish to be screened at your GP practice, you can arrange to have a cervical screening test at a well woman clinic, family planning clinic or at the genito-urinary medicine (GUM) department of your local hospital. You can use the FPA's postcode finder to find your nearest clinic.
When a screening test may not be recommended
In some cases, you may not need cervical screening or it may be recommended that you delay having a screening test. These situations are described below.
Sexually inactive women
The risk of cervical cancer is very low in women who have never had sex. As the risk is so low, women in this group may choose not to have cervical screening when invited.
However, if you are not currently in a sexual relationship but have been in the past, it is recommended that you have regular cervical screening.
Cervical screening tests are not usually recommended while you are pregnant, unless you have missed previous screening appointments or you have had abnormal results in the past.
If you are pregnant and have always attended your screening appointments without having abnormal results, it's usually recommended that you wait until three months after giving birth before having a screening test.
If you are invited to cervical screening while pregnant and you are unsure whether you need to be tested, contact your GP or practice nurse for advice.
Women aged 65 and over
Women aged 65 and over whose last three test results were normal are not invited for further cervical screening tests. This is because it is very unlikely that women in this group will go on to develop cervical cancer.
If you are over 64 and have had abnormal test results, you will continue to be invited for screening until the cells return to normal. Women aged 65 and over who have never had screening are entitled to a test.
Women who have had a hysterectomy
Women who have had a total hysterectomy (an operation to remove the womb and cervix) will no longer be invited to attend cervical screening, as it is not necessary for them.
Women who have had a hysterectomy that has left all or part of the cervix in place will be invited for screening once their post-operative care has finished.
Women who have had a total hysterectomy to treat cancer, or who had cervical intra-epithelial neoplasia (CIN, a type of cervical cell change that can lead to cancer) at the time of having a total hysterectomy, may need another type of test called a vault smear.
This is where a sample of cells is taken from the vagina, close to where the cervix used to be. Vault smears are part of the follow-up treatment for hysterectomy and are not part of the cervical screening programme.
Cervical cancer: Tina's story
Regular smear tests saved Tina's life and her fertililty. She talks about her experience of cervical cancer and her treatment. Note: the purpose of a smear is to detect pre-cancer, that is pre-invasive disease.
The screening process
You will receive a letter through the post asking you to make an appointment for a cervical screening test. The letter should contain the details of where you need to contact for the appointment.
You can have cervical screening at your GP surgery or a family planning clinic. Most women choose to go to their GP practice. Screening is usually carried out by the practice nurse. You can ask to have a female doctor or nurse.
If possible, try to book an appointment during the middle of your menstrual cycle (usually 14 days from the start of your last period), as this can help ensure a better sample of cells is taken.
If you use a spermicide, a barrier method of contraception or a lubricant jelly, you should not use these for 24 hours before the test as the chemicals they contain may affect the test.
The screening test
The cervical screening test usually takes around five minutes to carry out. You will be asked to undress from the waist down and lie on a couch, although you can usually remain fully dressed if you are wearing a loose skirt.
The doctor or nurse will gently put an instrument, called a speculum, into your vagina. This holds the walls of the vagina open so that the cervix can be seen. A small soft brush will be used to gently collect some cells from the surface of your cervix.
Some women find the procedure a bit uncomfortable or embarrassing, but for most women it is not painful. If you find the test painful, tell the doctor or nurse because they may be able to reduce your discomfort. Try to relax as much as possible because being tense makes the test more difficult to carry out. Taking slow, deep breaths will help.
In the laboratory
In recent years, the process of processing cell samples has been improved to make it more accurate. The cell sample is now taken using liquid-based cytology (LBC), rather than the "Pap" (Papanicolaou) smear test that was used previously.
The head of the brush on which your cells have been collected is broken off into a small pot of preservative liquid or rinsed directly into the preservative liquid.
The sample will then be sent to a laboratory where it will be treated to remove any other material that may have been picked up, such as mucus or blood. It is then examined under a microscope to see whether there are any abnormal cells.
In some areas, the first test carried out on the sample will be to see if the human papillomavirus (HPV) is present. Only if it is found will the laboratory need to check for abnormal cells.
Research has shown that LBC is more accurate than the Pap smear test and decreases the number of inadequate screening results. This means you are less likely to be called back for a repeat screening because your test was unclear.
Improvements across all aspects of cervical screening now mean that all women should receive their results within two weeks of their screening test.
As with all screening tests, cervical screening is not 100% accurate and does not prevent every case.
However, regular screening can stop up to 75% of cervical cancers developing, which is why it is important to attend screening when invited.
Results of cervical screening
The results of your screening test will be sent to you in the post, with a copy sent to your GP.
Before you leave your screening, ask when your results are expected and how you will receive them. In some cases, you may need to contact your GP or clinic to get your results.
The Cervical Screening Programme aims to notify people of their results within 14 days.
The types of screening result you may get will depend on whether your screening sample has been checked for human papilloma virus (HPV) before any other test was carried out. If this happens with your sample, then you will have received a leaflet about ‘HPV primary screening’ with your screening invitation.
If the first test carried out on your sample is to look for abnormal cells (‘cytology’), then the results you may get are as follows.
A normal test result means that no abnormal cell changes have been found. No action is needed and you do not need another cervical screening test until it is routinely due.
You may be told that you need to have a repeat test because the first one could not be read properly. This may be because not enough cells were collected, they could not be seen clearly enough or an infection was present.
If this the case, you will be asked to go back so that another sample of cells can be taken, usually after about three months.
If you have abnormal results, you may be told that you have:
borderline or low-grade changes (called ‘dyskaryosis’)
moderate or severe (high-grade) dyskaryosis
If your result is low-grade, it means that although there are some abnormal cell changes, they are very close to being normal and may disappear without treatment.
In this case, your sample will be tested for HPV. If HPV isn’t found, you are at very low risk of developing cervical cancer before your next screening test. You will be invited back for routine screening in three to five years time (depending on your age). If HPV is found, you will be offered an examination called colposcopy, which looks at the cervix more closely.
If your result is high-grade dyskaryosis, your sample will not be tested for HPV, but you will be offered colposcopy in order to check the changes in your cervical cells.
All these results show that you have abnormal cell changes. This does not mean that you have cancer or will get cancer. It just means that some of your cells are abnormal and if they are not treated they may develop into cervical cancer.
HPV primary screening
If your sample is first tested for HPV (known as HPV primary screening), then what happens next will depend on if HPV is found or not.
HPV negative means that no HPV was found. In this case, no further tests need to be carried out on the sample, and you will simply be called back for screening again in three to five years time (depending on your age).
HPV positive means that the human papilloma virus has been found in your sample. In this case, the sample will then also be tested for abnormal cells. If no abnormal cells are found, then you will be asked to come back for screening again in 12 months time to see if the HPV has gone.
If abnormal cells are found along with an HPV positive result, you will be referred for colposcopy.
A colposcopy is a simple examination that uses a special microscope called a colposcope to examine your cervix. Having colposcopy is very much like having cervical screening. The colposcope doesn’t go inside you. It can identify the extent of abnormal cells and helps determine whether you need treatment.
A small sample of tissue (biopsy) may also be taken from your cervix during colposcopy.
Treating abnormal cells in the cervix
If cervical screening shows that you have abnormal cells in your cervix, treatment to remove the affected cells may be recommended.
In some cases, you may be offered treatment at the same time as your colposcopy. A colposcopy is an examination that uses a special microscope called a colposcope to examine your cervix and determine the extent of cell abnormality. More extensive types of treatment may require a separate appointment.
The type of treatment you will be offered will depend on how many abnormal cells you have in your cervix and how severe the cell changes are.
For many of the commonly used treatments, you will be given a local anaesthetic beforehand. This means the area being treated will be numbed but you will remain awake throughout the procedure.
The possible treatments are described below. It's important that you discuss them with your GP before deciding which to have.
Large loop excision of the transformation zone (LLETZ)
Also known as LEEP or diathermy, LLETZ is a procedure that uses a fine wire and an electrical current to cut away the affected area of tissue and seal the wound at the same time.
The advantage of this treatment is that the cells are removed rather than destroyed, so the tissue can be sent for further tests to confirm the extent of the cell changes and make sure the area of your cervix that contains the cells has been removed.
A cone biopsy is a small operation that in most cases requires an overnight stay in hospital.
A cone-shaped piece of tissue is cut away from your cervix to remove all of the abnormal cells. You may need a general anaesthetic (where you are asleep during the procedure).
Cryotherapy involves using a cold probe to freeze and destroy the abnormal cells in the cervix.
Sometimes referred to as laser ablation, the procedure uses lasers to identify and destroy abnormal cells in the cervix.
If necessary, a laser can also be used to remove a small piece of the cervix itself.
During cold coagulation, a hot probe is applied to the cervix to burn away and remove the abnormal cells.
Risks of treatment
Although removing or destroying the abnormal cells in your cervix can help reduce your risk of cervical cancer, there are a number of downsides to treatment you may want to discuss with your doctor.
For example, there is a chance that the abnormalities detected in your cells will return to normal without any treatment. However, it is not possible to know if this will happen and treatment is usually only recommended when repeated tests continue to show abnormalities, or if the abnormalities are more severe (high-grade).
There is also some evidence to suggest that some types of treatment may increase your risk of giving birth prematurely (before the 37th week of pregnancy), or having a child with a low birth weight, in the future. However, the treatments associated with this risk are rarely used nowadays and the alternatives mentioned above are considered much safer.
HPV testing after treatment
Six months after receiving treatment for abnormal cells in your cervix, a cervical screening test should be carried out to check for any cell changes.
If the test shows no changes, or only borderline or low-grade changes, the sample will also be tested for human papilloma virus (HPV).
If HPV is not found, you will not need to be screened for another three years.
If HPV is found, or more significant cell changes are detected, you should be referred for another colposcopy.