Antenatal Care - Vasa Praevia

Question 1

What is Vasa Praevia?

Answer 1

The foetal vessels are within the foetal (chorioamniotic) membranes (exposed) and travel across the internal cervical os, meaning they are more prone to bleeding during membrane rupture.

Question 2

Anatomy of Umbilical Vessels (2).

Answer 2

1. Foetal Membranes surround the amniotic cavity and developing foetus.
2. Foetal vessels = 2 Umbilical Arteries + 1 Single Umbilical Vein.

Question 3

Physiology of Umbilical Vessels (2).

Answer 3

1. Umbilical Cord (contains Wharton’s Jelly - connective tissue and foetal vessels) inserts directly into the placenta.
2. The foetal vessels are never exposed and are always protected.

Question 4

Exposed Sites of Umbilical Vessels (2).

Answer 4

1. Velamentous UC - UC inserts into choriomaniotic membranes and foetal vessels travel unprotected through membranes before joining placenta.
2. Accessory/Succenturiate Lobe of Placenta - connected by foetal vessels that travel through chorioamniotic membranes between placental lobes.

Question 5

Types of Vasa Praevia (2).

Answer 5

1. Type I - foetal vessels are exposed as Velamentous UC.
2. Type II - foetal vessels are exposed as they travel to Succenturiate Lobe.

Question 6

Risk Factors of Vasa Praevia (3).

Answer 6

1. Low Lying Placenta.
2. IVF Pregnancy.
3. Multiple Pregnancy.

Question 7

Diagnosis of Vasa Praevia (3).

Answer 7

1. Early Diagnosis by US Antenatally.
2. Clinical Diagnosis - APH in 2nd/3rd Trimester.
3. Clinical Diagnosis - Pulsating Foetal Vessels seen in Membranes through Dilated Cervix.

Question 8

Management of Vasa Praevia (2).

Answer 8

1. Asymptomatic - Anticipatory Corticosteroids from Week 32 and Elective C-Section (34-36 Weeks).
2. APH - Emergency C-Section.