At the time of ovulation, an endometrial thickness of 9 mm is normal. However, if the patient is at the time just after menstruation, abnormalities need to be considered. In addition, there is also a possibility of abnormality if the patient is a menopausal woman with an endometrial thickness of 9mm. The endometrium varies cyclically under the influence of estrogen and progesterone and usually has no fixed thickness. At the time of ovulation, the thickness of the endometrium is mostly 8-12mm, and an endometrial thickness of 9mm is normal. If it is just after menstruation, the endometrium is usually about 3-5mm thick. At this time, the endometrium is 9mm thick, there may be abnormalities, such as incomplete endometrial shedding, which often requires medication under the guidance of a professional doctor. For women after menopause, endometrial thickness of 9mm is considered endometrial thickening. After menopause, women’s endometrium gradually becomes thinner, and this is defined by 5mm. If it exceeds 5mm, the possibility of endometrial thickening needs to be considered, and further hysteroscopy and endometrial biopsy should be performed to exclude the possibility of endometrial polyps, endometrial lesions and other diseases. However, if the patient is diagnosed, surgical excision is often required.