Atlas of visual inspection of the cervix with acetic acid for screening, triage, and assessment for treatment

The following changes observed 1 minute after application of acetic acid are reported as VIA-positive:

Dense acetowhite areas in the TZ with well-defined margins:
High-grade cervical precancers appear as distinct dense, opaque acetowhite areas in the TZ and close to or attached to the SCJ. The margins of the lesions are well defined and may be either flat or raised from the surface. In the presence of multiple lesions with different characteristics, the VIA diagnosis will be based on the lesion with the worst features.

The size of a lesion may vary. Cervical precancers can present as large dense acetowhite areas covering most of the ectocervix, or as small lesions located in the TZ and attached to the SCJ or close to the external os (if the SCJ is not visible).

The inner margin of the acetowhite area may not be visible if the lesion extends beyond 2 mm into the endocervical canal.

The interpretation of the VIA test is often difficult in postmenopausal women. Dense acetowhite areas on a background of pale atrophic epithelium may be missed unless examined carefully. The most severe part of the lesion may be inside the endocervical canal and not detectable on VIA.

In high-grade precancers, the epithelium tends to peel off as a result of minor trauma (during speculum insertion or collection of cervical samples), exposing the red stroma underneath. Such areas of missing epithelium (erosion) within a dense acetowhite area indicate the presence of high-grade precancer or even early invasive cancer. The exposed underlying stroma is visible as red patches with bleeding points.