Cervical Smear Screening Test

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.

In the UK, women are routinely invited to have regular cervical screening tests as part of the National Cancer Screening Programme . The tests are done to prevent cervical cancer (and not to diagnose cancer as some people wrongly think). During each test some cells are removed from the cervix with a plastic brush. The cells are examined under a microscope to look for early changes that, if ignored and not treated, could develop into cancer of the cervix. If abnormal cells are found, these can be treated (removed), during a procedure called colposcopy.

A cervical screening test involves taking a sample of cells from your cervix. The cells are taken from an area of the cervix called the transformation zone (TZ), also called the squamocolumnar junction (SCJ). This area marks the divide between the cells that line the uterus – called columnar cells, and the cells of the cervix – called squamous cells. At this meeting point, the cells are continually dividing and growing. This means there is more chance of the cells here developing abnormalities that could become cancerous. In young women this area is generally easy to see. The surface of the cervix is normally shiny, smooth and pale pink in colour. The columnar cells that line the uterus and the cervical canal are reddish and more grainy in appearance.

A thin plastic stick with a small brush at the end is used to remove some cells gently from the surface of the cervix. The brush has plastic bristles which are longer in the middle. These bristles are placed into the cervical os. As the brush is rotated round 360°, the shorter bristles splay out and remove cells from the TZ on the surface of the cervix. The brush is rotated around the cervix five times, in a clockwise direction. This is because the bristles have a cutting edge that only works when rotated clockwise. This procedure is not painful. The cells on the brush are then sent to the laboratory.

In older, postmenopausal women, the TZ may be more difficult to see. Often this is because it has been drawn up into the cervical canal. The cervix is also often much smaller. For these women, a different shaped brush (called an endocervical brush) is used to reach the cells in the cervical canal.

Liquid-based Cytology

Liquid-Based Cytology (LBC) is a way of preparing the cervical samples for examination in the laboratory. It has now replaced the traditional smear tes t in the UK. Two systems for LBC are in use. Both systems use brushes which look similar. In one, the head of the brush that contains the cells is broken off into a pot that contains special preservative liquid. The brush head is sent to the laboratory in the pot (this is the SurePath® brand method). In the other system, the brush is rinsed in the preservative to wash the cells into the pot. The brush is then discarded (this is the ThinPrep® brand). In both methods, the procedure to obtain the cells is the same. It is just how the cells on the brush are dealt with that is different between the two methods. The liquid is sent to the lab where it is spun to separate out the cells from the preservative and other material such as mucus and blood. The cells are then placed on a slide and examined under a microscope.

LBC is now the preferred technique for cervical screening as it is more likely to produce a good set of cells that can be examined under the microscope. With the older smear method, about 1 in 10 tests had to be repeated because cells were not seen clearly or too few cells were present. This was often because of mucus and blood that was also smeared on to the slide. LBC is overall a more reliable test. A repeat test is much less likely to be needed with LBC (about 2 in 100). The LBC slides are easier to examine, speeding up time in the laboratory. This leads to faster results for women.

LBC also gives the opportunity to perform other tests on the same specimen. Tests for human papillomavirus (HPV) are possible on an LBC sample. HPV has been shown to cause cancer of the cervix (cervical cancer). Scientists are currently investigating whether adding HPV testing to the LBC specimen helps doctors to decide who needs treatment and more frequent cervical screening – and, who can have tests less frequently.

Doctors and nurses will still commonly refer to cervical screening tests as smear tests when talking to patients. From a patient point of view it really makes no practical difference how the cells are collect ed from the cervix; the main part of the examination, using the speculum, is the same .

The NHS Cervical Screening Programme

The NHS Cervical Screening Programme invites all women for regular tests automatically. You need to be registered with a GP, as this is how the programme gets your name. It is therefore important that your GP has correct address details for you. A computer system is used. Your record on the computer is updated when you have a test so it knows when your next one is due. You should get a letter asking you to make an appointment to have a test when it is due. Computerised recall systems are good – but not foolproof. Cervical screening is a free service on the NHS.

• First invitation for screening in England is at age 25. It is age 20 in Scotland, Wales and Northern Ireland.
• Routine recall (repeat screening test):
• Age 25 years: first invitation to cervical screening in England.
• Age 25-49 years: cervical screening tests are every 3 years. In Scotland, Wales and
• Age 50-64 years: cervical screening tests are every 5 years. o Age 65 years: routine cervical screening ceases.

Women over 65 years of age should be screened if: They have not had a cervical screening test since the age of 50. Or if a recent cervical screening test has been abnormal. (Cervical screening does not stop simply due to age until a woman with a previously abnormal cervical screening test has had 3

negative results).

Results of Cervical Screening Test

Cervical screening tests examine a sample of cells from the cervix. They cannot examine all of the cells. Cell results are called cytology and Cervical cytology results are reported as:

• Of which there are several grades or degrees of abnormality:

1. Borderline.
2. Mild dyskaryosis.
3. Moderate dyskaryosis. o Severe dyskaryosis.
4. Invasive  or glandular neoplasia.

Normal result

About 9 in 10 routine cervical screening tests are normal. You will be sent a letter inviting you for another one in 3-5 years, depending on your age. A normal result means you have a very low chance of developing cervical cancer. It is not a guarantee that cervical cancer will not occur. No screening test is 100% accurate. Some tests will be falsely reassuring (so called false negative results) – where the test is reported as normal but an abnormality is present. This is why it is important to have tests regularly. Cervical cancer takes years to develop from the earliest abnormalities, so there should be plenty of opportunity to detect abnormalities before problems do develop. (It is also possible to have false positive results. This means that a result is incorrectly labelled as abnormal. This can cause a lot of worry, but usually the colposcopy examination will reveal that things are normal.)

Inadequate test

This sometimes occurs, but is far less common now that the LBC technique is used. About 2 tests in every 100 are inadequate and need to be repeated. Inadequate simply means no result can be given as not enough cervical cells were present for examination under the microscope. It might be that the laboratory can only see cells from the vagina or columnar cells from the endometrium, or that there were just too few cervical cells. In the unusual event that a woman has three inadequate t ests in a row, the National Cervical Screening Programme advises that she be referred on for colposcopy examination (see under Colposcopy)

Abnormal result

About 1 in 20 tests is reported as abnormal. There is a range of changes that may occur. In nearly all cases, these changes do not mean cancer. Dyskaryosis is a medical term used to describe abnormal cell changes, seen with cervical screening. Dyskaryosis is not cancer. About 9 out of 10 cases of dyskaryosis revert back to normal on their own, without treatment. Nearly all abnormal tests show no more than small changes in the cervical cells. Dependent on the degree of abnormality, women with abnormal results may:

• Have a repeat cervical screening test at a shorter time interval.
• Be referred to a gynaecologist or to a colposcopy clinic – for further examination of the cervix +/- treatment. The urgency of this referral depends on the actual result of the cervical screening test.

Borderline Change

Borderline change is the mildest abnormality seen on cervical screening. About 3-4 in 100 cervical cytology results are borderline. Whilst the cells are not quite normal, they are not abnormal enough to be categorised as dyskaryosis.

Mild Dyskaryosis

Mild dyskaryosis is a common abnormal result from cervical screening. It is found that about 2 tests in every 100 show mild abnormalities of the cervical cells. Most of these changes go back to normal without any treatment.

Moderate or Severe Dyskaryosis

For even fewer women, cervical screening will show moderate or s evere dyskaryosis. About 6-7 in every 1,000 smear tests show either of these abnormalities. If your smear shows moderate or severe dyskaryosis it is still very unlikely that you will have cervical cancer. The main difference is that these changes are less likely to return to normal by themselves, so you will probably need some treatment. Treatment will happen at colposcopy.

Invasive or Glandular Neoplasia

Less than 1 cervical screening test in 1,000 has one of these, more serious abnormalities. Neoplasia means new growth of cells. Invasive neoplasia on a smear suggests cervical cancer might be present. This is not proven until a sample of cervical tissue (a biopsy) has been taken at colposcopy.

Glandular neoplasia is another significant abnormality that c an be seen on cervical screening. It suggests that there is an abnormality in the lining of the womb (the endometrium), rather than on the cervix. This is because glandular cells (found lining the womb) are different to the ones normally found on the cervix. Glandular neoplasia again does not necessarily mean cancer, but cancer needs to be excluded. You will probably need to have colposcopy and may need to have a small camera passed into the womb (called hysteroscopy).

It is important to remember that it is rare for an actual cervical cancer to be found on cervical screening. Remember that screening is designed to find early changes that could become cancer in the future, if left untreated.