Women with heavy blood clots during menstruation may have to consider the following causes: i. If during menstruation, their menstrual volume, menstrual cycle and menstrual period are within the normal range and only simple blood clots appear, it may be caused by the manifestation of blood clotting due to cold clotting and blood stasis. Second, if the bleeding volume at the onset of menstruation is high and has exceeded twice the normal menstrual volume, and there are many blood clots, it should be considered to be caused by anovulatory gonorrhea, which in serious cases may cause dizziness, weakness, panic and other anemia symptoms, mainly due to ovarian endocrine dysfunction. For women with endometrial lesions, such as atypical hyperplasia or complex hyperplasia of the endometrium, it may also cause heavy menstrual clots. In some women, menstrual clots are caused by adenomyosis and multiple fibroids, which increase the size of the uterine cavity and result in abnormal contractions.