Cervical precancerous lesions, as the name implies, are the precursors of cervical cancer, and the technical term is called cervical intraepithelial neoplasia, which includes low-grade intraepithelial neoplasia and high-grade intraepithelial neoplasia of the cervix (high-grade intraepithelial neoplasia also includes carcinoma in situ). Cervical intraepithelial neoplasia, like cervical cancer, is caused by the same etiology, namely HPV infection. Like many premalignant tumors, cervical intraepithelial neoplasia is a relatively long stage, and statistically, it can take as long as 5 to 15 years from the time it begins to form until it eventually progresses to cervical cancer. Therefore, we have plenty of time to stop it from developing into a real “killer”. In fact, the cure rate of cervical pre-cancer is very high, close to 100%. So the question is, since the treatment of cervical precancer is so important, how do we detect it? Before that, it is necessary for us to understand the structure of the cervix. The surface of the cervix is mainly composed of squamous epithelial cells, which are located at the periphery, pale pink and look smooth, and columnar cells, which are near the opening of the cervix, pale red and finely granular, and look rough. The area between the two is called the migratory zone, and the cells in this area are most prone to abnormalities. When the cervix is infected by external pathogens such as HPV, the cells in the migratory zone are the first to develop lesions. Depending on the severity of the lesions, we classify them as low-grade squamous intraepithelial neoplasia (formerly CINI grade) and high-grade squamous intraepithelial neoplasia (formerly CINII and CINIII grade). Since these lesions are very subtle, they must be diagnosed under a microscope after biopsy. Some people may ask: “Cervical precancerous lesions should have symptoms, right? Can we not wait until symptoms appear before we get tested?” . Unfortunately, most cervical precancerous lesions do not have any symptoms and must be detected by examination. In fact, routine screening for cervical cancer in China is also an important means to detect cervical precancerous lesions, and many patients are detected through screening and routine physical examination. The most important diagnostic methods include: 1. gynecological examination; 2. cytological examination (cervical TCT); 3. vaginal high-risk HPV test; 4. histopathological examination (colposcopy + cervical biopsy, cervical LEEP, cervical conization, etc.), which are described below. First of all, gynecological examination can be said to be the prerequisite for the diagnosis of gynecological diseases, through which we can roughly determine whether there are lesions in the cervix and where they are located. However, many precancerous cervical lesions are not very different from normal cervical lesions and can simply appear as cervical erosion, so we need to use the following very important methods. Cervical cytology, which plays an important role in cervical cancer screening. Previously, traditional Pap smear was used, which is inefficient in diagnosis and troublesome to take. Currently, the most commonly used test is cervical thin-layer liquid-based cytology, or cervical TCT for short, which is an upgrade and improvement of the traditional Pap smear and is not only convenient to collect materials, but also significantly more accurate. It only requires a few swipes on the cervix with a special small brush, and the report can be issued in one to two days. Possible TCT reports for cervical intraepithelial neoplasia include: atypical squamous cells of undetermined significance (ASC-US), atypical cells without excluding high intraepithelial lesions (ASC-H), low grade squamous intraepithelial lesions (LSIL) and high grade squamous intraepithelial lesions (HSIL). If such a report is obtained it indicates the possibility of cervical precancerous lesions and further colposcopy is recommended. High-risk vaginal HPV testing is becoming increasingly evident and is now commonly used in combination with cervical cytology as an indispensable part of cervical cancer screening. The so-called high-risk HPV refers to a group of HPV viruses that are highly associated with cervical cancer and precancerous lesions, mainly including types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68. The test result can be positive for one virus or several; in either case, it indicates that the person tested is already carrying the HPV virus. In general, women with HPV infection persisting for more than one year have a significantly increased chance of developing cervical intraepithelial neoplasia, especially types 16 and 18, as these two viruses account for about 70% of cervical cancers, so colposcopy is recommended regardless of the cytology results. After all, the above methods are only preliminary screening and there are many misdiagnoses and missed diagnoses which need to be further clarified by colposcopy. If necessary, doctors will perform cervical biopsy under colposcopy and for some older patients with atrophic cervical canal, cervical canal scratching is also needed to clarify the lesions in the cervical canal. However, even the diagnosis of cervical intraepithelial neoplasia by colposcopy is not always final. Because the biopsy has relatively little tissue, it cannot represent the lesions of the entire cervix; in other words, it cannot completely exclude the possibility of cervical invasive cancer. Therefore, further cervical LEEP or cervical conization is needed, and only then can we obtain enough tissues to ensure the accuracy of diagnosis.