Cord presentation is where the umbilical cord is between the presenting part and the cervix, with or without intact membranes; cord prolapse is where the cord lies through the cervix with ruptured membranes.
About 0.5% of deliveries are complicated by cord prolapse, especially in cases of premature labour, non-cephalic presentations and multiple pregnancies.
Cord prolapse carries a perinatal mortality rate of nearly 1%. Asphyxia can develop due to pressure on the cord or from vasospasm of the umbilical arteries.
Although there is no method to anticipate cord prolapse, women at high risk (non-longitudinal lie after 37 weeks of gestation; unstable lie beyond 37 weeks of gestation; preterm rupture of membrane with non-cephalic presentation) should be offered an inpatient stay to minimise adverse outcomes in the event of cord prolapse. In addition, rupture of membranes should prompt examination by speculum and/or digital examination.
Other indicators of cord prolapse include abnormal fetal heart rate patterns, especially if after an event such as rupture of membranes.