The main methods of examination of the endometrium are: 1. Vaginal ultrasound, which is the most important method to check the endometrium. If the thickness of the endometrium is checked, it can be done after the 10th day of the menstrual cycle. If the endometrium is checked for abnormal endometrial lesions such as endometrial polyps or endometritis, it can be done at any time during the non-menstrual period. 2. Pathological examination. Patients with endometrial polyps who are found to have abnormal endometrial hyperplasia after ultrasound examination, in order to further confirm the specific nature of the lesion, the 3.Hysteroscopy. Patients with thin endometrium, fluid in the uterine cavity and suspected endometrial adhesions found by ultrasonography can be further diagnosed by hysteroscopy.