How long is too long? Application of acetic acid during colposcopy: a prospective study

Application of acetic acid to the cervix followed by colposcopic assessment with or without colposcopically directed biopsy is the standard test used to detect dysplastic lesions of the cervix. However, there is no evidence-based common standard defining how exactly to perform this test.

To prospectively define the optimal timing for the colposcopic assessment of acetowhite lesions.

Consecutive women referred to our colposcopy unit were recruited. Using a standardized colposcopy protocol, we recorded the most severe colposcopic lesion 1, 3, and 5 minutes after application of acetic acid (primary study end point). The time to first appearance of the most severe colposcopic lesion, highest staining intensity, and fading of the most severe colposcopic lesion were video documented (secondary study end points, assessed independently by 3 raters). Results were compared using parametric and nonparametric tests.

A total of 300 women were included. After 1 minute, 290 of 300 patients (96.7%) were diagnosed with the most severe colposcopic lesion. This proportion did not improve after 3 minutes (290/300 [96.7%]) or after 5 minutes (233/264 [88.3%]). The proportion of minor and major changes continuously declined over time from 142 in 300 (47.3%; 1 minute) to 107 in 264 (40.5%; 5 minutes) and from 110 in 300 (36.7%) to 91 in 264 (34.5%), respectively. The median time until the first appearance of the most severe colposcopic lesion was 13.5 (interquartile range, 3-27.25) seconds and was significantly lower in high-grade squamous intraepithelial lesion (7 [interquartile range, 1-20] seconds) compared to low-grade squamous intraepithelial lesion (19 [interquartile range, 9-39.5] seconds; P < .001). We observed fading of acetowhite lesions in 78% of cases, occurring at a median of 191 (interquartile range, 120-295) seconds after application of acetic acid. Fading started earlier in high-grade squamous intraepithelial lesion compared to low-grade squamous intraepithelial lesion (179.5 [interquartile range, 110- 253.25] versus 212.5 [interquartile range, 146.5-300]; P = .044). Overall, the net difference between colposcopic assessments at 3 minutes versus at 1 minute was 1 more high-grade squamous intraepithelial lesion and 1 less low-grade squamous intraepithelial lesion.

It is reasonable to conclude that the best time to identify lesions is 1 minute after the application of acetic acid. Continued evaluation for up to 3 minutes may be considered reasonable for an optimal high-grade squamous intraepithelial lesion yield. However, fading of acetowhite lesions is common, especially in high-grade squamous intraepithelial lesions, and supports a recommendation of not prolonging colposcopy beyond 3 minutes.