In the early stages of pregnancy, the presence of black vaginal scum means that the patient has vaginal bleeding. Only the amount of vaginal bleeding is low and the blood stays in the vagina or uterine cavity for a longer period of time, so it turns black. The black blood mixed with vaginal secretions turns into black slag. It is important to consider the possibility of pre-eclampsia or ectopic pregnancy, especially if the patient has abdominal pain or abnormal discomfort, such as cramping, etc. The patient must have blood chorionic gonadotropin, progesterone and ultrasound to determine whether the pregnancy is intrauterine or extrauterine, and whether there is abnormal embryo development or embryo arrest. In addition, if the patient has black residue in the vagina, along with increased vaginal discharge and itching, it may be due to inflammatory disease, and a gynecological internal examination and leukocyte test are needed to confirm the diagnosis.