Vaginal bleeding during pregnancy without lower abdominal pain, mainly consider the following three reasons: first, need to exclude placental factors, mainly placenta previa or placenta praevia, in the state of urine in the obstetric ultrasound can clearly determine the location of the placenta; second, need to exclude the situation of preeclampsia, preeclampsia is a typical symptom of vaginal bleeding accompanied by abdominal pain, but there are some patients with vaginal bleeding and no obvious abdominal pain. However, some patients have less vaginal bleeding and no obvious abdominal pain, at this time, ultrasound examination of the placenta is in a normal position; third, need to rule out cervical lesions, need to do cervical cancer screening before pregnancy, if there is no pre-pregnancy test at about 12 weeks of pregnancy can be repeated gynecological examination to rule out cervical lesions.