Vasa Praevia

Question 1

Define vasa praevia

Answer 1

The foetal vessels run through the free placental membranes within 2cm of the cervix, below the presenting foetal part.

Question 2

What is the risk of vasa praevia

Answer 2

As the foetal vessels are now unprotected by placental tissue or wharton’s jelly of the umbilical cord, the vasa praevia is likely to rupture in active labour, or when amniotomy is performed to induce or augment labour

Question 3

What are the types of vasa praevia

Answer 3

Type 1: Vessels are connected to a velamentous umbilical cord (attachment to the membranes surrounding the placenta instead of the central mass)

Type 2: The vessels connects the placenta with a succenturiate or accessory lobe (smaller lobe separate to the main placenta)

Question 4

What is Benckaiser’s haemorrhage

Answer 4

the haemorrhage of blood when the vessels are ruptured in vasa praevia

Question 5

What is a succenturiate placenta

Answer 5

A small part of placenta is separated from the rest of placenta
The accessory lobe is developed from activated villi on the chorionic laeve
A leash of vessels connects the mass to the small lobe through membranes

Question 6

What are the risk factors for vasa praevia

Answer 6

Foetal anomaly - bilobed placenta or succenturiate lobes
Hx of a low-lying placenta in the second trimester
Multiple pregnancy
IVF

Question 7

What is the prevalence of vasa praevia

Answer 7

Uncommon in the general population, prevalence ranges between 1 in 1200 and 1 in 5000

Question 8

What is the foetal blood volume at term

Answer 8

80-100ml/kg

Question 9

What are the symptoms of vasa praevia

Answer 9

Presents with PV bleeding after RoM followed by rapid foetal distress

Dark-red vaginal bleeding (Benckiser’s haemorrhage)
Painless

Question 10

What are the signs of vasa praevia on examination

Answer 10

Bimanual
- Palpation of the pulsating foetal vessels inside the internal os
- Dark red vaginal bleeding

Question 11

What investigations should be done for vasa praevia

Answer 11

Bloods: Kleihauer test, electrophoresis, FBC, cross-match, G&S, coagulation screen, LFTs, Rh, VBG
Other: CTG, abdominal US, TVUSS with colour doppler imaging

Question 12

What is the role of ultrasound scans in vasa praevia

Answer 12

Diagnosis
or
Prenatal diagnosis is most effective around
midpregnancy (18–24 weeks of gestation) but needs to be confirmed during the third trimester
(30–32 weeks of gestation)

Question 13

What is the management for vasa praevia

Answer 13

1. A-E assessment
2. 34 weeks → admit
3. Stabilise the patient: 2x wide bore cannula + fluid ± transfusion
4. Consider steroids and magnesium <32 weeks
5. In labour → EMCS
6. Rhesus negative → anti-D immunoglobulin

Placental pathological examination to CONFIRM diagnosis if acute foetal compromise during delivery

Question 14

What should be done if vasa praevia is diagnosed prenatally

Answer 14

Prophylactic hospitalisation at 30-32 weeks
Repeated USS to monitor persistence of vasa praevia
Give corticosteroids to mature foetal lungs from 32 weeks
ELCS at 34-36 weeks

Question 15

What are the complications of vasa praevia

Answer 15

No major maternal risk but dangerous for the foetus: Associated with very high perinatal mortality from foetal exsanguination

Question 16

What is the prognosis for vasa praevia

Answer 16

Foetal mortality rate is at least 60% despite urgent caesarean delivery
Survival rates of 95% have been reporting when the diagnosis is made antenatally via ultrasound, which is then followed by ELCS