正常妊娠时胎盘附着于子宫体的前壁、后壁或侧壁 ,如果胎盘部分或全部附着于子宫下段 ,并覆盖在子宫颈内口上 ,称之为前置胎盘 ,其是产科严重并发症之一 ,虽然发病率较低 ,但能造成产前或产后大出血、感染 ,有时情况危急甚至危及产妇生命。近年来剖宫产率不断上升 ,人流刮宫次 In normal pregnancy, the placenta is attached to the anterior, posterior or lateral walls of the uterus. If the placenta is partially or completely attached to the lower uterine segment and covers the cervix, it is called the placenta previa, a serious obstetric complication First, although the incidence is low, but can cause prenatal or postpartum hemorrhage, infection, and sometimes critical or even endanger the lives of mothers. In recent years, cesarean section rate rising, flow cesarean times