Umbilical cord prolapse creates an acute interruption of fetoplacental circulation. The cord's two arteries carry deoxygenated blood from the fetus to the placenta, while the single vein returns oxygenated blood. When the presenting part compresses the prolapsed cord during contractions, fetal PaO2 drops rapidly, triggering chemoreceptor-mediated bradycardia. Sustained compression leads to progressive metabolic acidosis, hypoxic-ischemic injury to the fetal brain and myocardium, and potential fetal death within minutes. The nurse must immediately recognize the emergency, initiate cord decompression maneuvers, manage the team response, and coordinate emergency cesarean delivery.