How can there be blood before menstruation

There is no menstruation, vaginal bleeding belongs to irregular vaginal bleeding. Common reasons: first of all, organic lesions, mainly considering bleeding caused by inflammation of the vagina vulva, or tumors of the cervix and uterus, as well as organic lesions of the ovary. If organic lesions caused by irregular bleeding, it is recommended to see a regular hospital after the correct treatment to intervene. Secondly, functional diseases, that is, menstrual disorders, more common may be women because of mental stimulation, climate change, chronic disease, excessive exercise or mental anorexia, excessive weight loss diet, drug effects, etc. will cause endocrine dysfunction, so the situation caused by menstrual disorders can generally be alleviated by drug treatment or adjustment of mood, rest mode, appropriate sports activities, etc.