Vasa Praevia

Question 1

Define

Answer 1

Pathophysiology:

o Foetal vessels course through membrane over the internal cervical os and below foetal presenting part, unprotected by placental tissue or umbilical cord à when baby descends, they can rupture the vessels

o Type 1 VP = velamentous cord insertion in a single or bilobed placenta

o Type 2 VP = foetal vessels running between lobes of a placenta with 1 or more accessory lobes

o Benckaiser’s haemorrhage = the haemorrhage of blood when the vessels are ruptured

· Risk factors:

• o Foetal anomaly (bilobed placenta or succenturiate lobes)
  
  • Foetal vessels run through the membranes joining separate lobes together
• o History of low-lying placenta in 2nd trimester
• o Multiple pregnancies
• o IVF

Question 2

Signs

Answer 2

Typical picture = ROM -> fresh PV bleeding + foetal bradycardia

• After the membranes rupture, the veins alone can’t hold the weight of the baby à bleeding

Foetal HR abnormalities – decelerations, bradycardia, sinusoidal trace, foetal demise

Signs O/E

Pulsating vessels inside the internal cervical os on VE in early labour - can palpate in the membranes

Dark red vaginal bleeding

Acute foetal compromise following SROM/ ARM- e.g. foetal bradycardia, decelerations

NOTE: Can be diagnosed at the anomaly scan

O/E -> you can palpate the vessels in the membranes, amnioscope can directly visualise this

Question 3

Investigations

Answer 3

Transabdominal and/or transvaginal USS may diagnose vasa praevia- colour doppler USS gives better accuracy

Kleihauer test (measures amount of foetal Hb in a mother’s bloodstream)

Haemoglobin electrophoresis – identify if foetal or maternal blood (takes a long time)

Question 4

Complications

Answer 4

Management: CS

No major maternal risk but dangerous for the foetus

o Foetus à the loss of relatively small amounts of blood can have major implications for the foetus = rapid delivery + aggressive resuscitation including use of blood transfusion if required are essential

o Prognosis – foetal mortality if presenting with haemorrhage is 60% but if identified antenatally its 3%

Question 5

Management

Answer 5

Antenatal Care

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

Delivery

• Elective caesarean section at 34-36 weeks (in asymptomatic women if diagnosed in 3rd trimester)
• Emergency caesarean section if diagnosed upon labour
• Neonatal resuscitation including blood transfusion if required
• Placental pathological examination to CONFIRM diagnosis if acute foetal compromise during delivery