Menstruation should be called menstruation, there are blood clots black material may be normal endometrial debris, uterine fibroids grow to the mucous layer caused by, residual blood clots in the uterine cavity and so on. 1. Menstruation is a physiological phenomenon, under normal circumstances, menstruation is discharged as a dark red liquid, if part of the liquid mixed with endometrial debris, vaginal epithelial cells and cervical mucus, oxidation in the vagina, discharged from the body is a dark red liquid, that is, menstrual blood, which may be accompanied by black blood clots. 2. If uterine fibroids are too large, growing under the mucous membrane, intermural muscle, etc., it will affect the normal endometrial shedding, and the menstrual blood may also be black with blood clots. 3. Postpartum or abortion, the uterus does not contract well, which can lead to residual blood clots in the uterine cavity, manifested as black menstrual blood with blood clots. Therefore, patients with abnormal menstruation are advised to consult a doctor in a timely manner to identify the specific cause of the problem and provide targeted treatment under the guidance of the doctor.