When the color of menstruation is particularly black like sludge when it first comes, it may be caused by cold, endocrine disorders, endometrial lesions, etc., and needs to be analyzed specifically. 1. Cold: at this time, the endometrium is stimulated by cold, which will lead to small blood vessel contraction, uterine smooth muscle spasm, menstrual blood discharge is not smooth, menstrual blood oxidization and manifested as a black situation. 2. Endocrine disorders: if there are abnormal changes in estrogen, androgen and progesterone, it may lead to the endometrium not being able to shed normally, causing abnormal bleeding and leading to black color. 3. Endometrial disease: If there is endometrial inflammation, abnormal proliferation of the endometrium, etc., it may cause abnormal shedding of the endometrium, resulting in low menstrual flow and the color is like black mud. If the black color of menstruation persists and cannot be relieved, it is necessary to go to the hospital in time and take standardized methods of treatment under the guidance of the doctor to promote the alleviation of the condition.