Sudden vaginal discharge of brown blood may be ovulation bleeding, menstruation, pregnancy, endocrine disorders, organic diseases and other causes, if it is not menstruation, it is recommended to consult a doctor in time to clarify the condition and timely compliance with the doctor’s instructions for treatment. 1. Ovulation bleeding: due to fluctuations in hormone levels during ovulation, some women may experience a small amount of bleeding or bloody leukorrhea, which lasts for a few days and will be relieved on its own, without special treatment, if the amount is large or accompanied by abdominal pain and other symptoms, it is recommended to consult a doctor in a timely manner. 2. Menstruation: Some women may have a small amount of bleeding at the time of menstruation or 1~2 days after the end of menstruation. The small amount of bleeding is easily oxidized and manifests itself as the symptom of brown vaginal blood flow, usually without special treatment. 3. Pregnancy: If a woman has a history of menopause and suddenly has vaginal bleeding, it may be preeclampsia, ectopic pregnancy, hyperemesis gravidarum, gestational trophoblastic disease and so on. 4. Endocrine disorders: polycystic ovary syndrome, fatigue, etc. can lead to endocrine disorders in women, need to use drospirenone ethinyl estradiol tablets, ethinyl estradiol cyproterone tablets, etc. to adjust menstruation. In addition, after taking emergency contraceptive pills or placing intrauterine device may have vaginal bleeding, if the amount of bleeding is not more than the amount of menstruation, can be temporarily observed, if necessary, remove the device. 5. Organic diseases: vaginitis, cervicitis, uterine fibroids, endometrial cancer, cervical cancer and other diseases may cause small amount of vaginal bleeding. If you have the symptom of brown blood coming out of the vagina suddenly, it is recommended that you go to the hospital in time. After the doctor’s interview, you should combine the symptoms with other symptoms and carry out the relevant examinations, so that you can find out the exact cause of the disease and follow the doctor’s instructions to treat the cause of the disease.