Before the menstruation, the leucorrhoea may be caused by the following reasons: First, it may be caused by the beginning of menstruation with less bleeding, menstruation is caused by endometrial necrosis, shedding, bleeding, in the beginning of menstruation 1-2 days, because the endometrial shedding is less, bleeding is very little, mixed with the leucorrhoea may cause with blood, is a normal phenomenon, in fact, is the beginning of menstruation. Secondly, it may be because of its own cervical erosion, cervical polyps, cervical inflammation, congestion, etc. In the case of premenstrual pelvic and uterine congestion may cause the cervical mucosa to shed and a small amount of bleeding, mixed into the leucorrhea resulting in leucorrhea with blood. Third, it may be endometrial lesions, pelvic inflammatory disease leading to a small amount of bleeding before menstruation. If the premenstrual leukorrhea with blood is longer, with 3-5 days, the gynecology department needs to combine the results of vaginal examination, ultrasound examination, etc. to see if there are other diseases causing bleeding.