Cervical Smears

Cervical screening is not a test for cancer. It is a method of preventing cancer by detecting and treating early abnormalities that, if left untreated, could lead to cervical cancer. The National Screening Programme came about following Health of the Nation (DH, 1993). Since its implementation, the NHS Cervical Screening Programme has been remarkably successful. It has saved a large number of women's lives and will continue to prevent about 4,500 deaths every year in England.

ELIGIBILITY

All women between the ages of 25 and 64 are eligible for a free cervical smear test every three or five years.

Reasons why women under 25 and women over 65 are not invited for cervical cytology (Sasieni et al., 2003):

  • Invasive cancer in women under 25 is rare, but changes in the cervix are common. This may mean that younger women may get an abnormal result when there is nothing wrong.
  • Evidence suggests that screening women under the age of 25 may do more harm than good by resulting in unnecessary investigations after false positive results. It is suggested that screening women from the age of 25 will help reduce anxiety as well as the number of unnecessary investigations and treatments in younger women.
  • Women aged 65 and over who have had three consecutive negative cervical tests in the preceding ten years are taken out of the recall system. The natural history and progression of cervical cancer means it is highly unlikely that such women will go on to develop the disease.
  • Women aged 65 and over who have never had a screen are entitled to one.

The NHS call and recall system invites women to attend their local GP for a screen. Women must be advised to register with a local GP clinic.

RISK FACTORS FOR CERVICAL CANCER

  • Certain types of human papilloma virus (HPV) are linked with around 95 per cent of all cases of cervical cancer (mainly types 16,18, 31, and 33).
  • Women with many sexual partners or whose partners have many partners.
  • Long-term use of oral contraceptives increases the risk (taking the combined oral contraceptive for 5 years or more in the presence of HPV virus). Condom use gives some protection.
  • Women who smoke are twice as likely to develop cancer as non-smokers.
  • Women with late first pregnancy have a lower risk than those with an early pregnancy; the risk increases with the number of pregnancies.
  • Women in manual social classes are more at risk than those in a non-manual social class.

Assessment of the cervix

The cervix is composed of two types of epithelium.

Columnar epithelium is generally inside the cervical canal, and therefore not usually seen. It is translucent and blood vessels are visible.

Squamous epithelium covers the intravaginal portion of the cervix. Its appearance is opaque and dull to the eye.

Where the different epithelia meet is the squamo-columnar junction (S-C J).

This exposed area of columnar epithelium on the ectocervix, over a number of years, is replaced by squamous epithelium by a process of metaplasia. This area is known as the transformation zone. It is this part of the transformation zone that is adjacent to the squamo-columnar junction that is most vulnerable to cervical intraepithelial neoplasia. Therefore, when the squamo-columnar junction is visible, the cervical sample must include the whole circumference of the S-C J and the adjacent 1 cm of squamous epithelium.

As has been mentioned, columnar epithelium appears red to the eye. While this is sometimes referred to as an 'angry' cervix, 'erosion' (though the surface is not eroded), or 'ectopy' (though the columnar junction is not ectopic or misplaced) a more accurate term is eversion. Laceration of the cervix associated with childbirth (ectropion) may expose more of the canal lined by columnar epithelium. This may be further exaggerated by opening the speculum. Nabothian follicles may also be seen on the cervix. As a result the cervix may have a knobbly appearance. These are mucus-retaining cysts caused by normal changes of surface columnar squamous epithelium. They are generally around 5 mm in diameter, but may be enlarged to 1 to 1.5 cm. Polyps may be seen on the cervix. Most are entirely benign and give rise to no symptoms.

Clinical suspicion of malignancy may include: an enlarged cervix with an irregular friable surface that is crumbling to the touch, large blood vessels that may bleed freely when rubbed by the end of the speculum, and sweet smelling but offensive watery discharge (NHSCSP, 1998).

METHODS OF SCREENING

The first stage in cervical screening is either a smear test or liquid-based cytology (LBC).

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