Whether a woman’s endometrium of 13 mm is serious or not, it is first necessary to clarify which age group the patient is. Endometrial thickening can be divided into physiological endometrial thickening and pathological endometrial thickening. Physiological endometrial thickening is mainly due to the endometrium being affected by changes in ovarian hormone levels, resulting in cyclical endometrial thickening, and it is more common for adolescent women and women of childbearing age to have 13 mm thick endometrium due to the more vigorous secretion of hormone levels in the body and the overall quality of the body. However, 13 mm thick endometrium in menopausal women may be caused by endometrial cancer or other lesions, which is a more serious condition. If the endometrium is 13 mm thick in adolescent and fertile women, as long as the menstruation is normal, it is within the normal range and is not a big problem; if it is combined with irregular menstruation, it needs to be further treated. If a postmenopausal woman has an endometrial thickness of 13 mm, she needs to go to the hospital as soon as possible to get the endometrium for pathological examination through hysteroscopy and diagnostic scraping, to make a clear diagnosis and to carry out timely treatment according to the correct diagnosis. Therefore, the endometrial thickness of 13 mm depends on the age of the woman, if she is a young woman with normal menstruation, then it is normal, if she is a woman with abnormal menstruation, she needs further treatment. If it is a young woman with normal menstruation then it is normal, if it is a woman with abnormal menstruation then it needs further diagnosis and treatment, if it is a woman in menopause then it needs more urgent diagnosis and treatment.