placenta praevia - GM

Question 1

placenta praevia is when

Answer 1

the placenta overlies the lower uterine segment
5% of women will have a low lying placenta at their 20 week scan, but only 0.5% at delivery because the placenta migrates during pregnancy

Question 2

grades of placenta praevia

Answer 2

grade 1: minor, placenta is low lying and not covering the os
grade 2: marginal, lower edge reaches internal os
grade 3: partial, lower edge partially covering the internal cervical os
grade 4: complete, lies over the internal cervical os

Question 3

risk factors for placenta praevia

Answer 3

• Hx of placenta praevia
• Hx of C-section
• advanced maternal age
• increasing parity
• smoking
• cocaine use during pregnancy
• Hx of spontaneous or induced abortion
• deficient endometrium
• IVF

Question 4

clinical features of placenta praevia

Answer 4

usually asymptomatic and detected on US at the 20-week scan

Question 5

symptoms of placenta praevia include

Answer 5

APH: painless bright red vaginal bleeding (>24 weeks gestation)
- light contractions may be present

Question 6

other important areas to cover in history

Answer 6

fetal movements
obstetric history: previous pregnancies, delivery mode, gestation and complications (previous c-sections increase risk)
endometriosis
IVF
risk factors (eg. smoking and drug use)
provoking factors: post coital

Question 7

which clinical examinations should be conducted

Answer 7

digital vaginal examination should not be performed: may trigger heavy bleeding
speculum examination may be performed to check that membranes have not ruptured and the cervix is closed

Question 8

typical findings on clinical examination

Answer 8

non-tender utuerus
vaginal bleeding
signs of shock (pallor, distress, cap refill, cool peripheries): if significant bleeding has occurred

Question 9

differential diagnoses

Answer 9

placental abruption
uterine rupture
vasa praevia
benign lesions
malignant lesions
infections

Question 10

how would you know if it was actually a placental abruption

Answer 10

usually painful, dark red blood, bleeding may be concealed
the uterus may feel woody or tense on examination

Question 11

how would you know if it was actually uterine rupture

Answer 11

this usually occurs in labour with a history of previous caesarean section

Question 12

how would you know if it was actually vasa praevia

Answer 12

where foetal blood vessels run near the internal cervical os (associated with the characteristic triad of vaginal bleeding, rupture of membranes and fetal deterioration)

Question 13

investigations for placenta praevia

Answer 13

cardiotocograph in women above 26 weeks

Question 14

lab investigations

Answer 14

FBC, U&Es, LFTs: useful to rule out hypertensive conditions such as HELLP or pre-eclmapsia
group and save/crossmatch: if large volumes of blood loss patient may require transfusion
clotting profile: important in the context of bleeding
kleihauer test: required if the woman is resus negative

Question 15

imaging

Answer 15

US is used to establish definitive diagnosis of placenta praevia
RCOG recommend the use of transvaginal US, as it improves the accuracy of placental localisation and is considered safe

Question 16

what should you do if a low lying placenta is seen at 20 weeks and the patient is asymptomatic

Answer 16

the patient should be rescanned at 32 or 36 weeks depending on whether it is major or minor
if praevia is still present, serial scans every 2 weeks and a final scan at 36/37 weeks to determine method of delivery

Question 17

when does placenta praevia warrant elective caesaarean

Answer 17

elective caesarian section for major placenta praevia at 38 weeks
if minor, trial vaginal may be offered. praevia should be at least 2cm away from internal os for vaginal to be offered

Question 18

placenta praevia may lead to

Answer 18

carries an increased risk of obstetric haemorrhage and hysterectomy

Question 19

management of APH caused by placenta praevia

Answer 19

rapid ABCDE assessment and resus
maternal resus should not be delayed to determine fetal viability if the patient cannot be stabilised or is in labour emergency c-section is recommended

Question 20

fetal complications of placenta praevia

Answer 20

fetal haemorrhage
intrauterine growth restriction
premature birth