How to distinguish between cervical precancerous lesions and cervical carcinoma in situ

The diagnosis method of cervical precancerous lesions is based on the medical history and clinical manifestations. Especially for those with contact bleeding, the possibility of cervical precancerous lesions should be considered first. A detailed systemic examination and gynecological examination should be performed, and the following auxiliary examinations should be used:

1. Cervical smear cytology is the main method for detecting precancerous lesions and early cervical precancerous lesions. However, attention should be paid to the correct sampling site and careful microscopic examination, as there may be a false negative rate. Therefore, it should be combined with clinical conditions and regular examinations to screen with this method.

2. Iodine test: Normal cervical or vaginal squamous epithelium contains abundant glycogen, which can be dyed brown by iodine solution, while endocervical columnar epithelium, cervical erosion and abnormal squamous epithelium (including squamous metaplasia, atypical hyperplasia, carcinoma in situ and invasive cancer) have no glycogen and therefore do not stain. In clinical practice, after exposing the cervix with a vaginal speculum, wipe off the surface mucus, and smear the cervix and fornix with iodine solution. If an abnormal iodine-negative area is found, a biopsy can be taken from this area for pathological examination.

3. Biopsy of the cervix and endocervical canal: When the cervical smear cytology examination is grade III to IV or above, but the cervical biopsy is negative, four-point biopsies should be taken at 6, 9, 12 and 3 o'clock at the junction of the cervical squamous column, or multiple tissues should be taken from the unstained area of ​​the iodine test and the suspected cancerous site, and sliced ​​for examination, or the endocervical canal should be scraped with a small scraper and the scraped material should be sent for pathological examination.