Cervical screening Flashcards
What is the aim of the NHS cervical screening programme?
to detect and treat premalignant lesions. (i.e. CIN, the step before cancer) and therefore reduce the incidence and mortality of squamous cell carcinoma (the most common type of cervical cancer.
What forms the basis of cervical screening?
Cervical smears
How often are women screened?
Women are screened every 3 years from 25-49yrs and every 5 years from 50-64yrs
What does a cervical smear involve?
The test involves opening up the vagina with a speculum and using a brush to take samples from the transformation zone. The brush, where the cells are lodged, are rinsed directly into preservative fluid. this is then sent to the cervical screening lab.
What is the process of screening? (negative results)
Cervical sample –> High risk HPV test (PCR test) –> hr HPV negative then routine recall - 3yr (25-49), 5yr (50 and over)
What is the process of screening? (positive results)
Cervical sample –> High risk HPV test (PCR test) –> hr HPV positive –> Cytology triage - A representative thin layer of cells is spread on slide and stained with the pananicolaou (pap) stain. This cytology sample is then examined by trained biomedical scientists who look for dyskaryotic cells. These are squamous epithelial cells.
How are samples tested?
Tested for high risk HPV (hrHPV) subtypes Using a PCR test
Why is it reasonable for the woman to return to routine call if the hr-HPV test is negative?
In the absence of hr-HPV, it is essentially not possible to develop CIN.
What is dyskaryosis?
Refers to abnormalities of the cell nucleus e.g. an irregular shape, an increased size. It is a term that is only used in cervical smear reports.
It is graded depending on the severity of the nuclear abnormalities:
- Low grade
- High grade (divided into moderate and severe)
What is the difference between dyskaryosis and CIN?
- Dyskaryosis is a diagnosis rendered on a cervical smear = screening test
- CIN is a diagnosis which can only be rendered on a cervical biopsy = Gold standard test
A smear showing dyskaryosis is a good predictor of the presence of CIN in the cervix - T/F?
True
Low grade (mild) dyskaryosis - predicts the presence of CIN1 in the cervix High grade (moderate) dyskaryosis - predicts the presence of CIN2 in the cervix High grade (severe) dyskaryosis - predicts the presence of CIN 3 in the cervix.
What is a colposcopy?
At colposcopy, the cervix is exposed using a speculum. The colposcopist carefully examines the cervix using the colposcope, both before and after the application of acetic acid.
Certain abnormal colposcopic appearances are associated with CIN eg. acetowhite epithelium.
However, CIN is a histological diagnosis and so a biopsy is required to confirm the diagnosis.
Management of CIN?
CIN1 is usually managed by observation and regular follow up smears.
CIN 2 and CIN 3 are usually managed by excision of the transformation zone with cutting diathermy under local anaesthesia - large loop excision of the transformation zone (LLETZ). The specimen is sent to the lab to be carefully examined histologically by a pathologist. Patients who have had a LLETZ for CIN are offered a repeat smear and high risk-HPV testing 6 months later.
HPV is associated with the following cancers
VAIN --> Vaginal cancer CIN1 --> CIN2 --> CIN 3 --> Cervical cancer VIN --> Vulval cancer Penile cancer anogenital warts AIN --> Anal cancer Oropharyngeal cancer
How often should someone with HIV be screened for HPV?
Annually
