Placenta praevia

Question 1

Define placenta praevia.

Answer 1

Placenta praevia (PP) is defined as the placenta overlying the cervical os. It can be complete, partial, marginal, or low-lying.

Question 2

What is the aetiology of placenta praevia? What are risk factors for placenta paevia?

Answer 2

Advanced maternal age

Multiple pregnancies

Tobacco use

Mechanism unknown. Only previous scarring can cause this alone, likely to be mix of risk factors.

Question 3

Summarise the epidemiology of placenta praevia.

Answer 3

Occurs in 0.3% to 0.5% of pregnancies worldwide.

Question 4

What are signs and symptoms of placenta praevia?

Answer 4

Scarred uterus

Painless PV bleeding

Previous ultrasound anomaly in first trimester

Lack of uterine tenderness

Low blood pressure and tachycardia

Question 5

What investigations can be performed for placenta praevia?

Answer 5

Uterine ultrasound with colour flow Doppler analysis

FBC

Group and save

Question 6

What is the management for placenta praevia?

Answer 6

Corticosteroids if <34 weeks

Increased scans

Anti-D if required

Potentially emergency C-section

Question 7

What are complications associated with placenta praevia?

Answer 7

Anaemia

Preterm birth

Abnormally adherent placenta

Disseminated intravascular coagulation (DIC)

Intrauterine growth restriction (IUGR)

Fetal death

Sudden infant death syndrome (SIDS)

Question 8

What is the prognosis for placenta praevia?

Answer 8

Placenta praevia seen in early gestation may migrate into a normal position as pregnancy progresses. About 85% of placentas that are praevia at about 15 to 20 weeks and about 33% that are praevia at 20 to 23 weeks will no longer be praevia at the onset of labour.

Maternal prognosis is generally good.

Fetal prognosis is generally good but may be compromised by excessive bleeding and intrauterine growth restriction.

Neonatal prognosis is dependent on the degree of prematurity along with the availability of specialist neonatal care.