Cervical smear

From Ganfyd

Sampling of cells from cervical os and ectocervix. The cervix is exposed using a vaginal speculum and cells retrieved with wooden spatulas or brushes. Traditionally, the retrieved material was immediately smeared onto the slides and fixed at the time of the procedure, hence the name. However, the quality of the resulting slides were variable and liquid-based cytology has largely replaced this as a superior method (migration in UK completed October 2008). The cervical material is now rinsed into a container for processing in the laboratory.

However, liquid-based cytology does not perform better than conventional Pap tests in terms of relative sensitivity and positive predictive value for detection of cervical cancer precursors;^[1] its advantage lies in the the lower rate of unsatisfactory initial results, including the possibility of further testing on the same sample, in particular, testing for high-risk HPV sub-types. It costs more.

The process of obtaining cervical cytology is more often referred to as a Papanicolaou test/smear, named after Georgios Papanikolaou, who pioneered the concept of obtaining cervical smears, the associated staining process and the early work of interpretating these slides. It is often shortened to a more colloquial 'Pap smear'.

Screening is primarily aimed at the detection of pre-malignant cells in asymptomatic women. This forms the basis of the cervical cancer screening programme.

Cytological features of invasive cancer can be detected, but symptomatic women with inter-menstrual bleeding, post-coital bleeding and post-menopausal bleeding may require colposcopy and/or examination of the upper female genital tract.

Abnormalities are generally reported according to categories set down by the BSCC (UK) or the Bethesda system (USA and most other parts of the world). The UK system grades cytological abnormalities primarily on nuclear abnormalities, that is dyskaryosis ('bad nuclei'), the severity of which generally correlates with histological cervical intraepithelial neoplasia.

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