Aunt refers to menstruation. A pile of blood during menstruation is a blood clot, which may be caused by physiological reasons such as large endometrial shedding or pathological reasons such as uterine fibroids, endometritis, endometrial polyps, etc., which need to be analyzed specifically. 1. Physiological reasons: because the endometrium shedding is relatively large, thus causing excessive menstrual blood in the uterine cavity into clots, do not worry too much, is a normal phenomenon. 2. Pathological reasons: increasing uterine fibroids, endometritis, endometrial polyps, etc. make changes in the intrauterine environment, affecting the shedding of the endometrium, causing blood clots. There may be other reasons for blood clots during menstruation, and you need to go to the hospital for gynecological examination and standardized treatment under the guidance of the doctor.