Placenta Praevia

Question 1

what is placenta praevia?

Answer 1

placenta lying wholly or partly in the lower uterine segment

Question 2

what is the epidemiology of placenta praevia?

Answer 2

• 5% of patients will have a low-lying placenta when scanned at 16-20 weeks gestatio
• incidence at delivery is only 0.5% - therefore most placentas rise away from the cervix

Question 3

what factors are associated with placenta praevia?

Answer 3

• multiparity
• multiple pregnancy
• embryos are more likely to implant on a lower segment scar from previous caesarean section

Question 4

what are the clinical features of placenta praevia?

Answer 4

• shock in proprotion to visible loss
• no pain
• uterus not tender
• lie and presentation may be abnormal
• fetal heart usually normal
• coagulation problems rare
• small bleeds before large

Question 5

how is placenta praevia diagnosed?

Answer 5

• picked up at 20 week abdominal ultrasound
• transvaginal ultrasound = gold standard

Question 6

what investigation should not be performed?

Answer 6

digital vaginal examination should not be performed before an ultrasound as it may provoke a severe haemorrhage

Question 7

what is grade I placenta praevia?

Answer 7

placenta reaches lower segment but not the internal os

Question 8

what is grade II placenta praevia?

Answer 8

placenta reaches internal os but doesn’t cover it

Question 9

what is grade III placenta praevia?

Answer 9

placenta covers the internal os before dilation but not when dilated

Question 10

what is grade IV placenta praevia?

Answer 10

placenta completely covers the internal os

Question 11

what advice should be given is a placenta is low-lying at 20 weeks?

Answer 11

• rescan at 32 weeks
• no need to limit activity or intercourse unless they bleed
• if still present at 32 weeks and grade I/II then scan every 2 weeks
• final ultrasound at 36-37 weeks to determine the method of delivery

Question 12

what delivery methods are used in placenta praevia?

Answer 12

• grade III/IV = elective caesarean between 37-38 weeks
• grade I = trial of vaginal delivery

Question 13

what happens if a patient with known placenta praevia goes into labour?

Answer 13

emergency caesarean section should be performed due to the risk of post-partum haemorrhage

Question 14

what is the protocol for a patient with placenta praevia with bleeding?

Answer 14

1. admit
2. ABC approach to stabilise the women
3. if not able to stabilise = emergency caesarean section
4. if in labour or term reached = emergency caesarean section