Cervical screening test
Introduction
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.
Cervical Screening Wales (CSW) invites women aged between 20 and 64 who live in Wales for a test every 3 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.
At present HPV is not routinely tested for, as it is difficult to detect in the laboratory. Sometimes changes that look like an HPV infection can be seen on a cervical smear or a cervical biopsy (if you have been to a colposcopy clinic). Research studies are ongoing to see if HPV testing could be used in the cervical screening programme, and what is the most accurate and appropriate.
Read more about the results of cervical screening tests.
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Why should it be done?
Regular cervical screening will help to detect abnormal cell changes in the cervix (the lower part of the womb) before cancer has had a chance to develop.
If any changes are found, your GP will discuss with you whether to wait and see if the changes go away on their own or whether you need treatment.
Abnormal changes in the cells of the cervix can be caused by certain types of the 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 lines parts of the body), such as those in your cervix, anus, mouth and throat.
In the UK, it is estimated that 8 out of 10 people 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.
There are high-risk and low-risk types of HPV. Types HPV-16 and HPV-18 are considered high risk for cervical cancer. If you are infected with these high-risk types of HPV, you are more at risk of developing cancerous cells in your cervix.
How common are abnormal results?
About 9 out of 10 cervical screening results are normal. Around 1 in 20 show mild cell changes. For most women with mild cell changes, the cells will return to normal without treatment.
If your results show abnormal cells, you will be sent for screening every six months to monitor the cells. You will only be given treatment if the cells do not go back to normal.
Approximately 1 in 100 test results show moderate cell changes and 1 in 200 show severe changes. If your results indicate more serious cell changes such as these you will have a colposcopy to investigate further. A colposcopy is a procedure where the surface of the lining of the cervix is closely examined.
It is very rare for cancer to be diagnosed from the results of a cervical screening test. Less than 1 in 1,000 test results show invasive cancer.
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When should it be done?
The NHS Cervical Screening Programme in Wales offers free tests to women between the ages of 20 and 64 who are registered with a GP.
Women who are registered with a GP are invited for screening tests based on a call and recall system. You should receive your first call for screening at 20. Unless any follow up tests are required, you will be recalled for screening after 3 years.
If you have not had a cervical screening test within the appropriate time, you may be offered one when you visit your GP or family planning clinic.
Make sure that your GP has your correct name and address and let them know of any changes so they can contact you when you are due to have a screening test.
If you are not registered with a GP surgery, or if you prefer, 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 Sexual Health Local Service Search to find your nearest clinic.
If you have treatment for abnormal cervical cells after your screening test, you will be asked to attend screening once a year for some years afterwards, depending on how serious the cell changes are.
If you are unsure when your next screening test should be, or if you have any questions about the NHS Cervical Screening Programme, you should contact your GP or practice nurse or visit the Cervical Screening Wales website.
First screening
If you've never had sexual contact with a man, you are at low risk, but not at no risk, of developing cervical cancer. It is still not entirely clear what causes abnormalities to develop. Often, it is because a virus has infected the cervix. This virus is called human papilloma virus (HPV) and is passed on during sexual contact.
HPV can be passed on in other forms of sexual activity apart from full intercourse. This applies to heterosexual women, bisexual women and lesbians. HPV is passed on through body fluids. This means that oral sex, transferring vaginal fluids on hands and fingers, or sharing sex toys can all be ways of being exposed to HPV.
If you're under the age of 20 and worried about your risk of developing cervical cancer, or you are concerned about other aspects of your sexual health, visit your GP or your local GUM clinic for advice.
Getting checked
If you have recently had a cervical screening test and the results were normal, but you then develop symptoms such as unusual vaginal bleeding, visit your GP or GUM clinic for a check-up.
There could be several different reasons for your symptoms, so further investigation is needed.
When a screening test may not be needed
Cervical cancer is rare in the following groups of women, who therefore may not need cervical screening.
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 one 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 for older women
In Wales, women are invited for cervical smears up to the age of 64. The screening programme stops then because women who have had normal smears up to this time are very unlikely to go on to develop cervical cancer in later years. There is also a chance that very minor changes due to low hormone levels can be found. This can then lead to unnecessary repeat smears and other investigations.
However, some women have had abnormal smears in the past and do need to have smear tests after the age of 64. This is to make sure that they have been properly followed up and that the abnormality does not come back. If this is the case, you will continue to receive invitations for smears.
If you have never had a cervical smear, you should ideally have one, regardless of your age. If you have never been sexually active, you can discuss this with your GP.
Although cervical cancer does occur in older women, it is often in women who have had no smears, or who have not had enough smears in the past. Even if all your past smears were normal, it is very important that you report any unusual bleeding or discharge to your GP.
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.
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 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 sampling is part of the follow-up treatment for hysterectomy but is not part of the cervical screening programme.
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How is it performed?
Providing that you are registered with a GP, you will receive a letter from your GP surgery or local Health Board asking you to make an appointment for a cervical screening test.
You can have the smear test at your GP surgery or family planning clinic. Most women choose to go to their GP or practice nurse. You can ask to have a female doctor or nurse if you would prefer one.
It is best to have the screening test in the middle of your menstrual cycle (between periods), so you should book your appointment to coincide with this.
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. 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 brush-like instrument will be used to gently collect some cells from the surface of your cervix.
The procedure may be 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 taking 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.
Research has shown that this new method of collecting and testing a sample of cells 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.
Read more about the results of cervical screening.
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Results
The results of your screening test will be sent straight to your GP or the clinic where the test was carried out. Your surgery or clinic may not need to contact you if your results are normal.
Before you leave your screening, ask when your results are expected and how you will receive them. If necessary, contact your GP or clinic to get your results.
Cervical Screening Wales provides all women who live in Wales their test results by post. They aim to provide the test results within 4 to 6 weeks of the test being taken, but sometimes it takes a little longer.
They should also contact you if your results are abnormal or if the test could not be read properly.
Below are the different types of results that you might receive after having a cervical screening test.
Normal
A normal test result means that there are no abnormal cell changes. No action is needed and you do not need your next cervical screening until it is routinely due.
Inadequate
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.
Borderline
If your result is borderline, it means that although there are some abnormal cell changes, they are very close to being normal and may disappear without treatment. You will be asked to return for another screening test six months later to check that the cells have returned to normal.
Abnormal
If you have abnormal results, you may be told that you have:
- mild or slight changes (mild dyskaryosis)
- moderate cell changes (moderate dyskaryosis)
- severe cell changes (severe dyskaryosis)
Dyskaryosis is a term used to describe the changes in the cells.
Your results may also refer to CIN. This stands for cervical intra-epithelial neoplasia, which is the term used to describe a type of abnormal cell change that can lead to cancer based on the tissue sample rather than the cells.
The grading system for these type of cell changes is explained in bullet points below.
- CIN 1 refers to mild changes
- CIN 2 refers to moderate changes
- CIN 3 refers to severe changes
All these results show that you have pre-cancerous cells. 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.
Not all abnormal changes need to be referred for further investigation or treatment. Your GP may recommend waiting to see if the changes disappear on their own and ask you to return for another screening in six months' time.
If further investigation is needed, your GP will refer you for another screening test or to a specialist (gynaecologist) for an examination called a colposcopy.
Colposcopy
A colposcopy is a simple examination that uses a special microscope called a colposcope. It can identify the extent of cell abnormality and helps determine whether you need treatment.
A small sample of tissue (biopsy) may also be taken from your cervix at the same time.
Read more about colposcopy.
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Treatment
If cervical screening shows that you have abnormal cells in your cervix, your GP may recommend they be treated.
The aim of treatment is to remove or destroy the abnormal cells in your cervix.
It may be possible for you to have treatment at the same time as your colposcopy. A colposcopy is an examination that uses a special microscope called a colposcope to determine the extent of cell abnormality. Other more invasive types of treatment will 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 changes are.
You will be given a local anaesthetic beforehand, which means that 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.
Cone biopsy
A cone biopsy is a small operation that in most cases requires an overnight stay in hospital.
A cone 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
Cryotherapy involves using a cold probe to freeze away the abnormal cells in the cervix.
Laser treatments
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.
Cold coagulation
During cold coagulation, a hot probe is applied to the cervix to burn away and remove the abnormal cells.
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