Colposcopy and histology
All the participants underwent colposcopy examination (3ML LED, Leisegang, Berlin, German) performed by a qualified gynecologist after TS detection finished. 5% acetic acid and 5% Lugol’s iodine solution were applied in turn onto the cervix to visualize cervical lesions. Cervical biopsies were obtained at the suspicious lesion area. If no suspicious lesion spotted, random biopsies of four quadrants were then obtained. In cervix of incomplete cervical TZ (type II or III), ECC was performed. Finally, pathological investigations for the collected specimens were performed by two expertized pathologists. Reports of pathological diagnosis according to CIN reporting system were referred as the gold standard. Status of p16 and Ki-67 immunohistochemistry (IHC) staining were recorded.