脐带
Umbilical cord prolapse occurs when the umbilical cord comes out of the uterus with or before the presenting part of the fetus. Umbilical cord prolapse should always be considered a possibility when there is a sudden decrease in fetal heart rate or variable decelerations, particularly after the rupture of membranes. With overt prolapses, the diagnosis can be confirmed if the cord can be palpated on vaginal examination. Without overt prolapse, the diagnosis can only be confirmed after a cesarean section, though even then it will not always be evident at time of procedure.