Under normal circumstances, menstruation is clinically possible when the endometrium is 1.0-1.2 cm thick, so if the endometrium is only 0.6 cm, menstruation is often not expected. If the endometrium is only 0.6cm before menstruation through ultrasound examination, this situation may also be clinically due to the thin endometrium caused by estrogen deficiency, or due to the endometrial damage caused by previous abortion, cleaning surgery, or diagnostic scraping, which results in endometrial adhesions, so that the endometrium becomes thin. In this case, it is recommended to combine the medical history with a hysteroscopy, if necessary, to separate the adherent tissues if there are adhesions. In addition, in case of endometrial tuberculosis, Mycobacterium tuberculosis destroys the endometrial cells, so it can also cause the endometrium to become thin, and in this case there will be no menstruation.