Cervical screening aims to detect abnormal changes to the cervix (the neck of the uterus or womb) before they can develop into cancer.  Safe and effective treatment for pre-cancerous lesions detected by screening will prevent progression to cancer.

What is a cervical smear test?

A cervical smear test is not a test to look for cancer. A cervical smear test is a screening test to look for abnormal cell changes to the cervix. Some cells with abnormal changes can develop into cancer if they are not treated. Treatment of abnormal cells is very effective at preventing cancer.

It is normal for cells on the surface of the cervix to go through changes.  However, cells can sometimes change in an abnormal way without causing any symptoms.  Cervical screening finds abnormal cells so that they can be treated before they develop into cancer.

Abnormal cells in the cervix usually change very slowly.  In the early stages, many will disappear by themselves, and no treatment will be needed.  For a few women, abnormal cells could develop into cervical cancer if not treated.

A screening test will not always pick up abnormalities.  However, if abnormalities have been missed in one test, it is likely that they will be picked up in the next test.  This is why it is important to have cervical smear tests every three years.

Studies indicate that when women have cervical smear tests every three years as part of a screening programme their chances of getting cervical cancer can be reduced by about 90 percent. 

The cervical smear test

There are two ways of processing a cervical smear.

• In the conventional (pap) smear test, the smear taker smears cervical cells onto a glass slide.  At the laboratory, these cells are stained and looked at under the microscope.
• Using liquid-based cytology (LBC), the smear taker places cervical cells into a liquid solution.  The laboratory then uses a machine to produce a layer of cells on a glass slide.  The cells are stained and examined under the microscope in the same way as in the conventional smear test.

Both of these methods can be used for a cervical smear test in New Zealand.  Studies have shown that both methods are of an acceptable standard.  Smear takers may offer women the choice of having either the usual smear or LBC.

Questions and answers on liquid-based cytology (LBC)

A copy of questions and answers on LBC can be downloaded from the Smear Takers section of this website (link shown) Questions and answers on LBC (September 2009)  

How accurate are cervical smear tests?

• There is a small chance that some abnormal cells will be missed during sampling or slide reading (called a false negative). Abnormal changes to cervical cells progress very slowly. It is likely that any abnormal cells missed at one regular check will be picked up at the next.  
• There is also a small chance that a result will say that abnormal cells have been found when the cervix is quite normal (a false positive). If the result from further testing shows that there are no abnormal cells, no treatment will be needed. 
• A cervical smear has a false negative rate of about 20 percent for high-grade lesions. The test is not reliable in the presence of clinical symptoms.