Brown discharge four days after abortion is normal. Brown discharge is a small amount of vaginal bleeding, which is the color formed by oxidation in the vagina due to the relatively small amount of blood. After abortion, the uterus and endometrium need a period of time to return to normal and there will be a little vaginal bleeding, which will gradually decrease and disappear in about a week. You can also take oral motherwort granules or new biochemical granules to help the uterus contract. When the uterus contracts, it will compress the blood vessels and it will stop the bleeding. You also need to go to the hospital for ultrasound about ten days after the operation to check the condition of the uterus. If there is residual material in the uterine cavity, a second operation to remove the uterus is needed if necessary.