Vasa praevia

Question 1

Define vasa praevia.

Answer 1

Vasa praevia is where one or more of the baby’s placental or umbilical blood vessels cross the entrance to the birth canal under the baby. Having vasa praevia increases the chance that if the membranes tear during labour (naturally or by a health professional), the blood vessels might also tear.

Question 2

What is the aetiology of vasa praevia?

Answer 2

The 2 main causes of vasa previa are velamentous insertions (where the cord inserts directly into the membranes, leaving unprotected vessels running to the placenta) (25–62%) and vessels crossing between lobes of the placenta such as in succenturiate or bilobate placentas (33–75%)

Question 3

What are the risk factors for vasa praevia?

Answer 3

Accessory placental lobes (succenturiate or bilobate)

Velamentous insertion of the cord

Placenta praevia

Multiple gestation

Post-IVF pregnancies

Question 4

Summarise the epidemiology of vasa praevia.

Answer 4

Rare

Prevalence is about 1/2500 to 5000 deliveries.

Question 5

What are the signs and symptoms of vasa praevia?

Answer 5

Painless vaginal bleeding

Rupture of membranes

Fetal bradycardia

Question 6

What investigations should be performed for vasa praevia?

Answer 6

Transvaginal ultrasonography

Question 7

What is the management of vasa praevia?

Answer 7

Prolong pregnancy

If >34 weeks give steroids for lung maturation + magnesium sulphate to stabilise and delay labour

C-section

Question 8

What are the complications of vasa praevia? What is the prognosis of vasa praevia?

Answer 8

Fetal haemorrhage

Fetal mortality rate may approach 60% if vasa praevia is not diagnosed before birth.