Being familiar with the risk factors that predispose a patient to cord prolapse is the first step toward preventing the complication. Recognizing the early warning signs is the first step toward averting a life-threatening disaster.
Who's at risk?
Multiparous patients are 60% more likely to experience umbilical cord prolapse.5 The presenting fetal part is less likely to be engaged at the onset of labor in a multiparous patient and if the membranes do rupture, it can allow the umbilical cord to pass beyond the unengaged presenting part. Multiple gestations delivering vaginally are also at risk but that risk is greater for the second twin because of a greater likelihood of malpresentation for the second twin.1,6,7 Murphy and associates showed that delivery at less than 37 weeks is independent of birth weight as a risk factor for umbilical cord prolapse.7 Polyhydramnios is yet another independent risk factor for cord prolapse, as it is frequently associated with unstable lie.8 Subsequent membrane rupture, whether spontaneous or artificial, can result in a fluid gush that inadvertently forces the cord to pass beyond the presenting part.
Which obstetrical interventions pose a danger?
Obstetrical interventions that involve manipulation or elevation of the presenting fetal part can predispose to cord prolapse by allowing the cord to pass alongside the presenting part and result in either overt or occult prolapse. Interventions that increase the likelihood of cord prolapse include artificial rupture of membranes, internal scalp electrode application, intrauterine pressure catheter placement, forceps or vacuum application, manual rotation of the fetal head, amnioinfusion, and external cephalic version.3,9 Keep in mind, however, that some of the evidence to "indict" these obstetric interventions has been challenged.