Placenta praevia

Question 1

What is placenta praevia?

Answer 1

• where the placenta is attached in the lower portion of the uterus, lower than the presenting part of the fetus
• Placenta praevia occurs in around 1% of pregnancies. It is a notable cause of antepartum haemorrhage.

Question 2

What is the difference between low-lying placenta and placenta praevia?

Answer 2

• Low-lying placenta is used when the placenta is within 20mm of the internal cervical os
• Placenta praevia is used only when the placenta is over the internal cervical os

Question 3

What are the causes of antepartum haemorrhage?

Answer 3

• placenta praevia
• placental abruption
• vasa praevia

Question 4

What are the risks associated with placenta praevia?

Answer 4

• Antepartum haemorrhage
• Emergency caesarean section
• Emergency hysterectomy
• Maternal anaemia and transfusions
• Preterm birth and low birth weight
• Stillbirth

Question 5

What are the risk factors for placenta praevia?

Answer 5

• Previous caesarean sections
• Previous placenta praevia
• Older maternal age
• Maternal smoking
• Structural uterine abnormalities (e.g. fibroids)
• Assisted reproduction (e.g. IVF)

Question 6

How is placenta praevia diagnosed?

Answer 6

-The 20-week anomaly scan is used to assess the position of the placenta and diagnose placenta praevia.

Question 7

What are the symptoms of placenta praevia?

Answer 7

• Many women with placenta praevia are asymptomatic
• may present with painless vaginal bleeding in pregnancy (antepartum haemorrhage)
• Bleeding usually occurs later in pregnancy (around or after 36 weeks)

Question 8

What is the management for placenta praevia?

Answer 8

• repeat transvaginal US scan at 32 and 36 weeks (if present on the 32 week scan)
• Corticosteroids are given between 34 and 35 + 6 weeks gestation to mature the fetal lungs, given the risk of preterm delivery
• Planned delivery is considered between 36 and 37 weeks gestation

Question 9

Why is planned delivery early in placenta praevia?

Answer 9

• planned early to reduce the risk of spontaneous labour and bleeding
• Planned cesarean section is required with placenta praevia and low-lying placenta (<20mm from the internal os
• Emergency caesarean section may be required with premature labour or antenatal bleeding

Question 10

What is the main complication of placenta praevia and how is it managed?

Answer 10

haemorrhage before, during and after delivery.When this occurs, urgent management is required and may involve:

• Emergency caesarean section
• Blood transfusions
• Intrauterine balloon tamponade
• Uterine artery occlusion
• Emergency hysterectomy