Most women who have a cervical screening test have a normal result. Some women’s tests will show that they have changes in the cells of their cervix. This is known as an abnormal result, which means that the laboratory has found some cell changes that may need further investigation. Often the changes may be due to inflammation or infection. Sometimes certain medicines, such as hormonal therapies for gynaecological conditions or breast cancer, can cause changes in the cervix. For this reason, it is important to let the person carrying out the screening know about any medicines that you are taking.

Sometimes the abnormality may be due to changes in the squamous cells of the cervix. This is known as CIN, which stands for cervical intra-epithelial neoplasia. The screening report may refer to the changes as dyskaryosis.

These abnormal cells are not cancerous, but if left untreated they can sometimes go on to develop into cancer of the cervix.

As the cells can sometimes develop into cancer, the changes to them are also sometimes called pre-cancerous changes.

CIN is divided into grades, which describe how far the abnormal cells have gone into the surface layer of the cervix.

• CIN 1 – Only one-third of the thickness of the surface layer of the cervix is affected.
• CIN 2 – Two-thirds of the thickness of the surface layer of the cervix is affected.
• CIN 3 – The full thickness of the surface layer of the cervix is affected.

With all three grades of CIN, often only a small part of the cervix is affected by abnormal changes.

CIN 3 is also known as carcinoma-in-situ. Although this may sound like cancer, CIN 3 is not cancer of the cervix. It is only if the deeper layers of the cervix have been affected by abnormal cells that a cancer has developed. However, it is important that CIN 3 is treated as soon as possible.

A screening test can show that CIN is present, but it cannot always show how deeply the abnormal cells go into the cervix. In order to find the grade of the CIN, further tests may need to be carried out. During the further tests, samples (biopsies) of the abnormal areas of the cervix may be taken. The biopsies are looked at under a microscope to find the grade of the CIN. This makes it easier for the doctor to decide on the most appropriate type of treatment for you.

Sometimes a screening test may find changes in the glandular cells that line the cervical canal (see diagram). Changes to these cells seem to go through the same stages as CIN, but are called CGIN, which stands for cervical glandular intra epithelial neoplasia. If left untreated these changes may develop into a type of cancer known as adenocarcinoma. It is much less common for changes to occur in these cells.

A cervical screening test can also detect early cancer of the cervix, but most women with an abnormal test result have early cell changes and not cancer.

Very few women with an abnormal test result actually have cancer of the cervix.