1临床资料患者,女,25岁,本院护士,停经40周,无不适,于2014年4月8日入院待产。孕妇以往月经规律,孕早期及孕24周行B超检查时,均为胎盘位于宫颈口边缘,孕期未做定期检查,现孕40周,要求行剖宫产术入院。查体:青年女性,神志清,精神紧张,胎位左枕前(LOA),胎心144次/min,先露固定,血HB 115 g/L,凝血四项无异常, 1 Clinical data Patients, female, 25 years old, nurses in our hospital, menopause 40 weeks, no discomfort, on April 8, 2014 admission to be produced. Pregnant women in the past, menstrual regularity, early pregnancy and 24 weeks pregnant line B-ultrasound, are located at the edge of the cervix in the placenta, pregnancy did not make regular checks, 40 weeks of pregnancy, requiring cesarean section admission. Physical examination: young women, conscious, nervous, fetal left anterior occipital lobe (LOA), fetal heart rate 144 times / min, first exposed fixed blood HB 115 g / L, no abnormal blood clotting,