Bleeding again after nine days of clean menstruation may be caused by reproductive system diseases, trauma, endocrine abnormalities, systemic diseases, etc. It is recommended to consult a doctor in time. 1. Reproductive system diseases: such as vulvar ulcers, cervical ulcers, cervical polyps, endometritis, uterine fibroids, uterine cervical cancer, etc., and the patient may also be accompanied by lower abdominal pain, vaginal discharge and other uncomfortable symptoms. 2. Trauma: such as riding across through the injury, foreign body damage to the vagina, etc., the patient may be accompanied by severe pain and obvious pressure pain at the site of injury. 3. Endocrine abnormalities: such as dysfunctional uterine bleeding, bleeding between menstruation, etc., the above symptoms can occur. 4. Systemic diseases: such as aplastic anemia, thrombocytopenic purpura, liver disease, etc., patients may also be accompanied by skin petechiae, ecchymosis, fatigue and other uncomfortable symptoms. If the patient bleeds again after nine days of menstruation, the patient should consult a doctor in time to find out the cause of the disease under the doctor’s guidance, and follow the doctor’s instructions to carry out the corresponding treatment if necessary.