A normal cervical cytology result does not mean that the possibility of cervical cancer has disappeared completely. Cytology alone can miss some lesions, so it is safer to have an HPV test at the same time.
The national cervical cancer screening offered every 2 years to women aged 20 and over checks only for changes in the shape of the cells, whereas an HPV test looks separately for infection with the high-risk viruses that are the main cause of the cancer. This article sets out how the two tests differ and why they should be taken together.
Is a cervical cytology test enough on its own?
Cervical cytology collects cells from the surface of the cervix and checks them for abnormal changes, and it helps to find cervical dysplasia, which can progress to cancer, at an early stage. Its accuracy is about 80%, however, so the report quite often reads normal even though a lesion is present.
A lesion confined to the deeper part of the cervix may not be sampled adequately during collection, and an early lesion does not immediately change the shape of the cells, so it is difficult to judge from the cytology result alone. Combining cytology with an HPV test reduces what is missed.
Is an HPV test needed even without symptoms?
In most cases HPV causes no noticeable symptoms after infection, and cases are reported in which a woman receives a normal cytology result and is then found, late, to have dysplasia within 1 to 2 years. Relying on the normal result alone means losing the chance to identify a lesion that has progressed.
For women with a family history, a previous finding of atypical cells, or bleeding or inflammation that continues, a check every 6 months to 1 year is recommended regardless of the national screening interval, and even without risk factors, having both tests together widens the options for responding.
- Family history — with a family history of cervical cancer, a check every 6 months to 1 year is recommended
- A finding of atypical cells — if this was seen in an earlier test, follow-up testing at shorter intervals is needed
- Persistent bleeding or inflammation — if it continues, a check is needed regardless of the national screening interval
How is an HPV test different from a cytology test?
Cytology examines the collected cells under a microscope to see whether their shape has moved outside the normal range, so it has a limitation: during the period before the cells change shape, it cannot pick up an abnormality even if the virus is present. An HPV test detects the genetic material of the virus, so infection can be confirmed even at the stage before cell changes appear.
The HPV test is not covered by the national screening programme and is an optional test that has to be added separately, so many women have cytology alone and move on. Considering that infection with high-risk HPV is the main cause of cervical cancer, however, taking both tests together is a way of lowering the risk.
How should vaccination and follow-up be managed for prevention?
If there is no vaccination history, the first step is to receive guidance on preventive vaccines such as Gardasil and decide whether to be vaccinated. Even after vaccination is complete, it cannot replace regular screening, so the habit of having both tests together should be kept.
Depending on the test results and risk factors, the timing of follow-up is set at 3 months, 6 months or 1 year, and when necessary a more detailed examination such as an HPV test or magnified imaging of the cervix is added so that a lesion can be managed promptly. This is safer than depending on a single normal result.
- Gardasil vaccine guidance — if there is no vaccination history, the decision on vaccination is made after a consultation
- Setting the follow — up interval — the timing is set between 3 months and 1 year according to risk factors
- Detailed examination — when needed, an HPV test or magnified imaging of the cervix is used to check for lesions
