Mannitol is a levonorgestrel IUD system. Bleeding one month after the removal of the cyst and the placement of the levonorgestrel intrauterine device, and the amount of blood is not large, is an abnormal situation. Under normal circumstances after the removal of the cyst usually half a month after the phenomenon will no longer have bleeding, there is still bleeding, there may be an infection in the uterine cavity or levonorgestrel intrauterine device system stimulation caused by bleeding. 1. Infection of the uterine cavity: If during the process of removing cysts or after cyst surgery, the usual cleaning is not paid attention to in place, there are bacteria, fungi, viruses and other infections, resulting in poor postoperative recovery, it will be easy to appear for a long time to bleed. 2. Levonorgestrel intrauterine sterilization system stimulation: levonorgestrel intrauterine sterilization system is a kind of drug ring containing hormones. When placed in the body, it may cause vaginal bleeding through the release of drugs. Therefore, it is clinically recommended that patients with this symptom should seek medical attention to identify the cause and stop the bleeding in time under the guidance of a doctor.