Umbilical cord prolapse is abnormal position of the cord in front of the fetal presenting part, so that the fetus compresses the cord during labor, causing fetal hypoxemia.
The prolapsed umbilical cord may be
Occult: Contained within the uterus
Overt: Protruding from the vagina
Both are uncommon.
Occult prolapse
In occult prolapse, the cord is often compressed by a shoulder or the head. The only clue may be a fetal heart rate pattern (detected by fetal monitoring) that suggests cord compression and progression to hypoxemia (eg, severe bradycardia, severe variable decelerations).
Changing the woman’s position may relieve pressure on the cord; however, if the abnormal fetal heart rate pattern persists, immediate cesarean delivery is necessary.
Overt prolapse
Overt prolapse occurs with ruptured membranes and is more common with breech presentation or a transverse lie. Overt prolapse can also occur with vertex presentation, particularly if membranes rupture (spontaneously or iatrogenically) before the head is engaged.
