Flat white acetic acid epithelium is mainly applied locally to the cervix during colposcopy. After this acetic acid is applied, if there is a localized lesion, a thicker, more clearly demarcated white acetic acid epithelium appears locally, indicating that a lesion may be present in the area. If there is a mustard yellow color when the iodine is reapplied, a biopsy is taken from the area and sent for pathologic examination, which often results in pathologic changes. If there is a thin acetic acid epithelium, it is often clinically normal and there is no need to be nervous. So the acetate epithelium should look at the thinness and thickness, and also to understand whether the border is clear, if the border is very clear, the possibility of lesions is very high.