Proliferative endometrium and partial glandular dilatation are usually considered as endometrial thickening, which generally includes endometrial hyperplasia, atypical hyperplasia of endometrium and endometrial cancer. 1. Endometrial hyperplasia: it can be categorized into simple endometrial hyperplasia and complex endometrial hyperplasia, which may easily induce irregular vaginal bleeding, amenorrhea and scanty menstruation. 2. Endometrial atypical hyperplasia: it is a more serious gynecological disease, also known as endometrial intraepithelial neoplasia, which is a kind of precancerous lesion. 3. Endometrial cancer: it is a kind of malignant tumor that develops in the endometrium and is common in perimenopausal and postmenopausal women. It is recommended that women should go to regular hospitals for further examination and treatment under the guidance of specialists after the cause of the disease is clarified.