The Tests used for Screening
The Smear Test
The traditional test uses a small disposable spatula, to take a sample of cells from the cervix. Sometimes a small brush is used instead of the spatula to collect the cells. The cells are spread on to a glass slide and sent to a laboratory to be examined under a microscope (cytology)
Liquid-based cytology
Liquid-based cytology (LBC), such as the ThinPrep® Pap test, is now the method of choice when collecting cells from the cervix. The sample is taken in a similar way to a smear, but uses a special brush that gently takes cells from the cervix. The head of the brush is then rinsed into a small container of preservative. The container is then sent to the laboratory to be checked. Liquid-based cytology has the advantage of an increased rate of disease detection, and a reduction in unsatisfactory results (inadequate smears cause unnecessary anxiety and inconvenience to women). There is also the added advantage of being able to perform additional tests out of the same vial, such as screening for HPV.
What are the benefits of testing?
Regular screening increases the chances of detecting cell changes at an early stage when treatment options are simpler and abnormalities more easily cured.
What are the limitations to the test?
A cervical smear test cannot pick up all abnormalities and there can be various reasons for this:
- Poor quality smear taking
- Inaccurate interpretation
- The abnormality is adenocarcinoma (which accounts for 10 – 20% of cervical cancers) and is difficult to pick up on this test
- The cancer develops between tests
As cervical cancer usually takes a few years to develop some of these limitations are addressed by having regular tests undertaken, so that something missed can be picked up the next time whilst it is still treatable.
As the test isn’t 100% accurate it is important you seek medical advice if you develop symptoms between having smears taken (eg vaginal bleeding between periods or after sexual intercourse, lower abdominal pain, urine retention or constipation).
New Technology
The TruScreen cervical probe is innovative technology which can identify cervical cancer or pre-cancerous cells in real time. The probe is placed gently onto the cervix at designated places and uses low level electrical signals and light to identify abnormalities, not just in the surface layer of cells, but also the deeper layers. Used alongside a cervical smear (taken by liquid based cytology) the combined test results are more accurate than either test in isolation.
When the test is completed (which takes approximately 1 minute) an immediate result will be produced – normal, abnormal or inadequate.
- An inadequate result means the test needs to be repeated.
- An abnormal result means that a cervical smear is not required and that the woman should be referred for a colposcopy
- A normal result is very reassuring but needs to be backed up by taking a smear in the conventional manner.
If the result of the smear is abnormal, even though the probe had been normal, the usual guidelines for abnormal smears (see 'next steps') remain.
