VIA procedure Ė Examination after application of 5% acetic acid Ė Abnormal features
The primary objective of VIA as a screening test is to identify women with the highest likelihood of having CIN2, CIN3, AIS, or cervical cancer and to correctly exclude women without any of these lesions.
Not all acetowhite changes on the cervix are due to high-grade cervical precancer or cancer, and not all acetowhite changes may be interpreted as positive on VIA. A high-grade cervical neoplasia is visible as a dense acetowhite area in the TZ and has a well-defined margin. Other conditions, such as inflammation, immature squamous metaplasia, flat condylomata caused by infection with low-risk HPV types, and CIN1, can also give rise to acetowhite changes with variable colour intensity and diffuse or irregular margins.
The VIA test is negative if there is no new white patch on the transformation zone 1 minute after application of acetic acid. However, not all white patches are VIA-positive.
A white area that appears on the cervix after application of acetic acid should be carefully examined for the features described in the next section to differentiate between the significant (and hence VIA-positive) and the non-significant (and hence VIA-negative) acetowhite areas.