source after one min of 3–5% dilute acetic acid application using a cotton swab or a spray. Detection of well-defined aceto- white areas close to the squamocolumnar junction (SCJ) indicates a positive result. Although aceto-whitening can occur in immature squamous metaplasia and in inflamed and regenerating cervical epithelium, aceto-whitening associated with cervical intraepithelial neoplasia (CIN) is well demarcated, intensely opaque and localised to the transformation zone. Early microinvasive cancers also turn
white after application of acetic acid. Aceto-whitening is thought to be due to a reversible coagulation of intracellular proteins following acetic acid application. The higher concentrations of intracellular proteins in neoplasia lead to the dense aceto-whitening following acetic acid application. Pooled estimates of sensitivity vary from 60-94% and specificity from 74- 94% for VIA to detect high-grade CIN, after adjusting for the effects of verification bias. The specificity of VIA is however lower among HIV-positive women, which may be attributed to high rates of co-infections in the lower genital tract; but again, as this group is at very high-risk for developing cervical cancer, they should be offered a more optimal screening program.
2. Visual inspection with Lugol’s iodine (VILI) VILI involves examination of the cervix with the naked eye to identify mustard-yellow areas on the cervix after application of Lugol’s iodine. The application of iodine results in brown or black colour staining in normal cells containing glycogen whereas in areas lacking glycogen, iodine is not absorbed and such areas remain colourless or turn yellow. Pooled estimates of sensitivity vary from 70-97% and specificity from 73-91% for VILI to detect high grade CIN. One of the main advantages of visual inspection based techniques is that it yields an immediate result, thus making it theoretically possible for treatment of abnormal lesions to be performed
«A number of countries in Africa have licensed the HPV vaccines»
at the same visit - the so-called “screen- and-treat” approach, without colposcopy or histological sampling. This method is inexpensive and can be carried out using modest equipment and widely available consumables without the need for a laboratory infrastructure. Although visual inspection methods present an appropriate strategy screening in low resource settings, these methods are prone to subjectivity and it is essential that good provider training and sustained quality assurance are maintained in order to achieve substantial gains in prevention of cervical cancer in routine settings.
3. HPV DNA testing A more objective and reproducible screening test is testing for HPV DNA that has shown to be more sensitive than cervical cytology in detecting high-grade lesions. Screening trials in South Africa and India suggest that HPV testing is an appropriate primary screening approach in low-resource settings to reduce cases of high-grade lesions, advanced stages of cervical cancer and mortality in HIV- infected and uninfected women. The limitations of HPV DNA testing
include the cost (i.e. US$20–30 per test), infrastructure, and time needed to obtain a result. Many of these limitations have been addressed by Qiagen (Qiagen Gaithersbur Inc., MD, USA) who have produced the CareHPV. This compact, portable, battery- operated system can produce results within three hours. Studies from China comparing CareHPV to VIA have shown greater sensitivity and comparable specificity. Regulatory approval is anticipated in developing countries in the near future, and this test will be provided at a low cost. CareHPV represents a promising alternative screening test; however, its performance and diagnostic value to detect pre-cancerous lesions need to be evaluated in African settings.
4. Colposcopy in cervical cancer screening In most countries colposcopy is used to evaluate women who have abnormal cytology. In some countries, specifically countries in Central and Eastern Europe
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