Sudden bleeding on the 18th day after cesarean section is usually related to the discharge of bad dew or poor uterine contraction, postoperative infection, etc. It can be treated by observation, medication or surgery. 1. Observation: Sudden bleeding after 18 days of cesarean section is usually related to the discharge of evil discharge after delivery, usually the evil discharge after delivery will be clean in about one month, and now there is bleeding and the evil discharge has not been discharged after 18 days of operation, such as there is no obvious abdominal pain and heavy bleeding phenomenon, you can observe for the time being, and there is no need to deal with special treatment. 2. Taking medication: if bleeding or accompanied by obvious abdominal pain and discomfort, may also be related to postpartum uterine contraction or infection, you can go to the hospital for ultrasound, under the guidance of the doctor to take motherwort granules, new biochemical granules to promote uterine contraction, such as infections, it is recommended to take amoxicillin, metronidazole anti-infective treatment. 3. Surgery: Cesarean section 18 days of sudden bleeding may also be and placenta or fetal membrane residue is not clean, 18 days after cesarean section and the uterine wall separation caused by bleeding, it is recommended to do ultrasound examination, large fetal membrane residue can be surgically removed from the uterus. Sudden bleeding 18 days after cesarean section should go to the hospital in time to improve the ultrasound examination, according to the specific causes of bleeding to give symptomatic treatment.