17 - Cord prolapse

Summary

Cord prolapse is the quintessential obstetric emergency. It occurs when part of the umbilical cord descends below the fetal presenting part. If the membranes are intact, the condition is called cord presentation. The frequency range is about 1/200 to 1/600 deliveries. The fetal risk is from hypoxia owing to physical compression of the umbilical cord vessels between the fetal presenting part and maternal tissues, or spasm of the vessels as a result of the colder temperature should the cord prolapse through the introitus. The perinatal mortality rate can be as high as 9%, even in well-equipped hospitals.

Aetiology

FACTORS THAT PREDISPOSE TO CORD PROLAPSE

Fetal

1. • Preterm labour and low birthweight

2. • Malpresentations

3. • Anomaly

4. • Multiple pregnancy

Placental

1. • Placenta praevia

Amniotic fluid

1. • Polyhydramnios

2. • Prelabour rupture of membranes: spontaneous and amniotomy

3. • Rupture of membranes in labour: spontaneous and amniotomy

Maternal

1. • Pelvic tumours, such as cervical fibroid

2. • Pelvic contraction

3. • Obstetric manoeuvres: rotation of fetal head, version, amnioinfusion

From the list of factors that predispose to cord prolapse, it can be seen that anything that interferes with the close application of the presenting part to the lower uterine segment and cervix will increase the likelihood of cord prolapse. Many of these factors are interrelated, such as preterm labour, malpresentations, multiple pregnancy and polyhydramnios.