Umbilical cord prolapse

Definition

• Cord prolapse means cord is anterior to presenting part after ROM; with intact membranes it is called a cord presentation.
• The danger lies in cord compression with fetal hypoxia.
• The CTG typically shows sudden prolonged or severe variable decelerations.

• In umbilical cord prolapse the cord exits the cervix before the presenting part; it is a rare obstetric emergency with high fetal morbidity and mortality.

Classification

• If the cord lies between the presenting part and the cervix regardless of membrane status, this is cord presentation; descent of the cord through the cervix is essential for prolapse.
• In overt prolapse the cord lies ahead of the presenting part and may protrude from the vagina; in occult prolapse it lies alongside it within the uterus and is often compressed by the shoulder or head.

Occurrence & epidemiology

Epidemiology

• The overall incidence is reported as 0.1–0.6%, higher in non-cephalic presentations, multiple pregnancies and earlier gestational ages; it has fallen markedly over the decades.

Aetiopathogenesis

Risk factors

• They include malpresentation, polyhydramnios, prematurity.
• So for amniotomy: only with a fixed presenting part.

Aetiology and risk factors

• Risk factors are malpresentation, especially in multiparous women, polyhydramnios, multiple pregnancy (especially the second twin), preterm labour and preterm prelabour rupture of membranes; overt prolapse is more common with breech presentation and transverse lie and, in vertex presentation, occurs mainly after rupture of membranes before the head is engaged.
• Up to 50% of cases are iatrogenic, for example from amniotomy, fetal blood sampling or insertion of a cervical balloon.

Clinical features

Clinical features and complications

• Compression of the cord by the descending fetus leads to fetal hypoxia and bradycardia, potentially resulting in death or permanent disability.
• In occult prolapse, a fetal heart rate pattern suggesting cord compression, such as severe bradycardia or severe variable decelerations, is often the only clue.

Diagnosis

• The diagnosis is made when the prolapsed cord is seen or felt in or outside the vagina, together with abnormal fetal heart rate patterns.
• Other causes of sudden fetal bradycardia such as maternal hypotension, placental abruption or uterine rupture are excluded.

Keep learning in the app

Further reading (selection)

1. StatPearls: Umbilical Cord Prolapse (NCBI Bookshelf)
2. MSD Manual Professional Edition: Umbilical Cord Prolapse
3. DocCheck Flexikon, Nabelschnurvorfall

Cross-references