Cervical smear abnormalities
What are cervical smear tests?
In 1928 Dr Papanicolaou discovered that cells from the cervix change in microscopic appearance before they become cancerous. These precancerous changes form the basis of identification and interpretation of precancerous cells and the cervical smear is most commonly know as the Pap smear.
There is a common misconception that the Pap smear is used to identify cervical cancer. In fact, Pap smears are not very good at identifying cervical cells that have already undergone cancerous (malignant) change. They are much more effective at picking up the changes in cervical cells, that if left untreated, might progress to cancer.
The frequency of routine Pap smears is dictated by the protocol of the Country in which you live in. In Australia, routine Pap smears are performed every 2 years and in the UK every 3 years. A balance is made by the authorities between the costs (financial to population and emotional/inconvenience to patients) of screening and the comparative prevention of cervical cancer with increased screening frequency.
Regular Pap tests every two years can reduce the incidence of cervical cancer by up to 90% in Australia, and save 1200 Australian women dying from the disease each year.
Obtaining a Pap smear
The instruments required for obtaining a pap smear often come in a packaged kit from the laboratories. These include two types of cytobrush, a glass slide and a container filled with a special medium.
The glass slide and container are labelled so as to identify the patient. The patient will be asked to confirm their name and date of birth.
New technology allows material from the cytobrush to be placed in a special liquid in a bottle (also labelled). The fluid can be spun down in the lab to isolate cells from the cervix. This is important if the material on the slide is obscured by blood.
A thin cytobrush is used to obtain an endocervical sample by introducing it into the endocervical canal and twisting the brush around.
A broader cytobrush is used to obtain a wider endocervical and ectocervical sample by introducing the forward tip into the endocervical canal and twisting the brush around. The outer parts of the brush pick up cells from the ectocervical area.
A speculum is introduced into the vagina. A bi-valve speculum is most commonly used but other speculums may be used. The cervix is brought in to view by opening up the speculum
Whilst taking a pap smear, it is important to be able to visualise all of the cervix. This is important because Pap smears are not very good at identifying cervical cancer, but a visual examination will likely identify a potentially malignant lesion that needs biopsy for diagnosis, even if the Pap smear is normal.
Once the cervix has been ‘swept’ with the cytobrush, the cytobrush is first applied to the glass slide, depositing cervical cells. The cytobrush is then placed in the medium in the bottle and swished around to deposit cervical cells into the medium. The material on the slide is then sprayed with a fixative solution and sealed in a plastic container.
The prepared slides are examined under a microscope by specially trained pathologist called cytologists. In Australia, the slide will be examined by two cytologists and a report produced that will reflect an agreed position on the normality or otherwise of the specimen.
Pap smear reporting
- No abnormal changes noted in the cells obtained from the cervix.
- Ideally, the sample would have contained both endocervical and ectocervical cells.
- In some cases, the report will indicate that though the cells sampled show no abnormality, there are no endocervical cells identified.
- Routine followup can occur if there are no endocervical smears as long as there is no history of cervical abnormality, the Pap smear has been reported as normal and the cervix looks visually normal.
- Atypia and non-specific minor changes
- Minor changes (‘atypia’).
- Caused by HPV, various bacterial, fungal or viral infections.
- Usually repeat Pap smear in 6-12 months and refer for colposcopy if persists.
- Cervical intraepithelial neoplasia-1 (CIN-1)
- Minor changes in size and shape of cervical cells.
- 6/10 will heal without intervention.
- 4/10 remain unchanged or progress to CIN-2 or CIN-3.
- Repeat Pap smear in 4-6 months and refer for colposcopy if persists.
CIN-2 and CIN-3
- CIN-2 also known as moderate dysplasia
- CIN-3 also known as severe dysplasia.
- More often considered as precancerous changes.
- If left untreated may progress, usually over several years, to cervical cancer.
- Referral for colposcopy + cervical biopsy will be made.
- More likely to require treatment.
Progression of change
CIN-1 (mild dysplasia)
CIN-2 (moderate dysplasia)
CIN-3 (severe dysplasia)
All abnormal, precancerous cervical changes have the potential to regress to normal. This is most likely to happen with CIN-1 and less likely to happen with CIN-3. Atypical changes may regress spontaneously or after appropriate treatment with antibacterial or anti fungal therapy if indicated. There is no spontaneous regression of cancer, whether micro-invasive or invasive.
Human Papilloma virus (hpv)
HPV is found in approximately 80% of the sexually active male and female population. It is passed on through close genital contact. HPV usually has no signs or symptoms but it can facilitate the development of penile, anal, cervical, vulval and vaginal cancers, as well as genital warts.
There are about 40 types of genital HPV. In most cases, HPV is eliminated by the immune system. HPV infection can sometimes persist. Some HPV types can cause genital warts. Other HPV types (called “high-risk” types) are cofactors that can cause cell changes on a woman’s cervix that can lead to cervical cancer over time.
The types of HPV that cause genital warts are different from the types that can cause cancer. HPV is very different from HIV or herpes infections. HPV does not make it harder to get or stay pregnant. Whilst the cell changes that HPV may cause can be treated, there is no direct treatment for the virus.
HPV vaccination is most effective when given before a person becomes sexually active. It triggers the formation of antibodies to produce immunity and therefore protects the body from disease. The HPV vaccine currently available in Australia is called Gardasil. This vaccine prevents infection with HPV types 16, 18, 6 and 11. HPV 16 and 18 are responsible for the majority (70% internationally; 80% in Australia) of cervical cancers. HPV 6 and 11 are responsible for 90% of genital warts.
Another vaccine called Cervarix is available, which protects against the same two high-risk HPV types (types 16 and 18). It does not protect against low-risk HPV types which cause genital warts. Some doctors may recommend this vaccine rather than Gardasil. Which ever vaccination you have, the vaccine will protect those who have never been exposed to these types of HPV.