Iodine coloration does not necessarily mean cervical cancer. Iodine staining means that normal cervicovaginal and vaginal squamous epithelium is rich in glycogen and stained brown or russet by iodine solution, while cervical erosion and cervicitis, due to abnormal cervical canal columnar epithelium and clinical epithelium, have no glycogen and cannot be stained. Squamous epithelial chemosis precancerous lesions and cervical cancer may show iodine non-staining, but for patients with high suspicion of cervical cancer, cervical smears or biopsies are taken from areas where iodine does not stain or where staining is poor, thus improving the positive rate and making the diagnosis more accurate.