What is the cause of black coffee?

Menstruation is coffee black, may be due to overwork, cold, gynecological inflammation and other reasons caused by stimulation. But sometimes too little menstrual flow, menstrual blood discharge delay can also be caused. Under normal circumstances, in addition to menstrual blood clots, there are some shedding endometrium and secretions. And menstruation generally presents red or dark red, women show this situation, need to go to the hospital in time to do B ultrasound, check the uterus, accessories, if necessary, also need to take blood to check sex hormone 6, to determine whether there are abnormal hormone levels in the body. During menstruation, women also need to pay more attention to rest, to prevent overwork and abdominal cold.