The shedding of large pieces of endometrium during menstruation can be due to physiological or pathological factors. Physiological factors may be caused by changes in hormone levels during menstruation; pathological factors include submucous fibroids, large interstitial fibroids, endometrial polyps, endometrial cancer, cervical cancer and so on. 1. Physiological factors: the endometrium of most women during menstruation is mainly shed in fragments, and occasionally there are cases of large pieces of shedding. As long as there is no obvious change in the time of menstruation and the amount of bleeding during menstruation, no special treatment is needed. 2. Pathological factors: some special gynecological diseases, such as submucous fibroid, large interstitial fibroid, endometrial polyp, endometrial cancer, cervical cancer, etc., may also lead to increased menstrual flow, and then the endometrium may shed large pieces of endometrial lining due to heavy bleeding. Therefore, in case of endometrial mass shedding during menstruation, it is recommended that the patient should go to the hospital in time for examination, and follow the doctor’s instructions for treatment after clarifying the cause of the disease.