A cervical smear test is a simple test that is used to detect changes in the skin of the cervix which, if left, might become a cancer. The smear test is used as a screening test of women who have no symptom, to identify those women who might be at risk of developing cervical cancer in the future.
A cervical smear test collects many thousands of cells that have fallen off the skin of the cervix (exfoliated). These cells are collected with a brush and transferred to the laboratory in liquid. They are spread on a microscope slide and stained using a special stain developed by the originator of the test, George Papanicolaou. These cells are then examined under a microscope by a specially trained pathologist.
The picture above shows the typical appearance of a normal smear. The nucleii of the cells in this photomicrograph are the dark blue structures seen within the cells and are very small compared with the size of the cell. The cytoplasm is the blue or orange area of the cells surrounding the small nucleii.
I had never had a Cervical Smear before so I was quite nervous. Mr McIndoe was very professional and courteous. He took the time to answer all of my questions and alleviate any doubts I had. He made sure that he understood what I was asking and that I understood what he explained.– Bethany, Shenfield
What is a Pap test?
The term Pap test is exactly the same as a smear test described above. In many countries the smear test is called a Pap test, short for the name of the man who invented the test, George Papanicolaou.
What age should I have my first smear test?
Smear tests should be taken from 20 years of age or alternatively two years after the beginning of sexual activity. Many countries have moved the age of first smear to 25 years of age but we believe this is a mistake. The peak incidence of cancer of the cervix is between 25 and 30 years of age and the smear test is used to pick up precancerous abnormalities that occur before cancer develops. Since the NHS has moved the beginning of screening from 20 year of age, the numbers of cancers in these young women has increased by 50%.
What is Liquid Based Cytology?
Smears were taken previously using a wooden spatula to collect the cells from the cervix and spread them directly onto a glass slide. This is where the name “smear” test comes from. A modern alternative to this is liquid based cytology where the cells are collected using a brush and transferred to fluid in the container. A machine in the laboratory spreads the cells in a thin uniform layer across the slide making it easier to see the individual cells.
The advantage of Liquid based cytology is that the cells are spread more evenly, and individual cells can be seen more clearly. The rate of unsatisfactory smears is reduced in addition.
What does an abnormal smear test mean?
An abnormal smear test suggests that possibly some of the cells on the skin of the cervix are growing faster than normal. We know that these areas of fast growing cells, if left over a number of years, may become a cancer.
The changes described above, causing an abnormal smear, involve just the skin of the cervix and are not cancer. These cells may have the ability to change into cancer if ignored over many years but many of these abnormalities will go away by themselves.
The smear test is just a screening test, so if the smear is abnormal, the next step is to diagnose exactly what is going on with colposcopy. Sometimes colposcopy will show that there is no abnormality at all, but sometimes the skin will be found to be abnormal which is called dysplasia or CIN.
Do the abnormal areas of skin cause any symptoms?
No. To the naked eye the skin of the cervix will look and behave entirely normally. No vaginal bleeding or discharge will occur and no pain or change in the menstrual cycle occurs when abnormal cells are present on the cervix.
What is a false positive smear test?
Smear test reports are not always correct. Occasionally, changes in the cells on the smear test are wrongly interpreted by the pathologist and so they report an abnormality when one doesn’t exist. Colposcopy can help to identify this problem, as no abnormality will be found.
What is a false negative smear test?
Smears can be reported as normal when a small number of abnormal cells are present. This happens most commonly when the abnormal areas on the cervix are very small so only a few of the cells on the smear test are abnormal. The labs have very careful quality control to make this an uncommon occurrence.
Sometimes the smear test has no abnormal cells at all even though a small abnormality exists on the cervix. A large study in the United States suggested that this might happen as often as 50% of the time. The screening program works because the abnormalities progress only very slowly over time so most women have had several smears by the time they are diagnosed.