There are many reasons for a dark brown vaginal discharge. When there is inflammation of the vagina and cervix, the erosive surface bleeds and enters the vagina and oxidizes, which may manifest as a dark brown discharge. When early in pregnancy, due to low progesterone and human chorionic gonadotropin, there will be a small amount of bleeding at this time, which may likewise cause dark brown discharge to occur, suggesting the possibility of preterm abortion. It is recommended to go to the hospital to have blood tests for progesterone and blood HCG, and depending on the situation, fetal preservation treatment is needed. When there is a viral infection or precancerous lesion in the cervix, it may also cause dark brown discharge. It is recommended to go to the hospital for TCT and HPV examination to rule out the possibility of precancerous lesion in the cervix. When there is endometrial hyperplasia and uneven echogenicity of the endometrium, it can also cause dark brown discharge, which should also be treated with anti-inflammatory and hemostatic treatment.