Dark brownish leucorrhea with blood is a sign of abnormal stale bleeding in the uterine cavity, which is a factor that can affect the normal proliferation and exfoliation function of the endometrium in women. The placement of the IUD may cause abnormal bleeding in the uterine cavity, resulting in a dark brown leucorrhea with blood. If the endometrium cannot adapt to this inflammatory reaction, or if the IUD is placed in the uterine cavity for too long, resulting in secondary infection of the endometrium, it may cause irregular peeling and bleeding of the local endometrium, resulting in blood in the leucorrhea. This situation should be analyzed according to the medical history of the IUD placement and the symptoms of dark brown blood in the leukorrhea, combined with ultrasound examination, to make a clear diagnosis and then treat the symptoms.