当胎膜破裂,脐带脱出于宫颈口外,降至阴道内,甚至露于外阴部,称为脐带脱垂,常发生在胎先露部尚未衔接时,如:头盆不称、胎头入盆困难、臀先露、肩先露、枕后位等胎位异常,胎儿过小、羊水过多,脐带过长、脐带附着异常及低置胎盘等[1]。 When the rupture of membranes, umbilical cord prolapse from the cervix outside, down to the vagina, or even exposed in the genitals, known as umbilical cord prolapse, often occurs in the fetal forepart has not yet converged, such as: the first basin is not known, the first into the basin Difficulties, buttocks exposed, shoulders first dew, occiput posterior position and other fetal abnormalities, the fetus is too small, too much amniotic fluid, umbilical cord is too long, abnormal umbilical cord attached and low placenta [1].