Placenta previa

Question 1

What is the definition of antepartum haemorrhage?

Answer 1

Any bleeding from the genital tract that occurs after 24+0 weeks gestation and before birth of the infant.

Question 2

What is the incidence of antepartum haemorrhage?

Answer 2

3-5%

Question 3

What are the uterine causes of antepartum haemorrhage (as opposed to lower genital tract causes)?

Answer 3

Placenta praevia
Placental abruption
Vasa praevia
Circumvallate placenta

Remember that up to 50% of cases of APH, no specific cause is found.

Question 4

What are the lower genital tract causes of antepartum haemorrhage (as opposed to uterine causes)?

Answer 4

Cervical ectropion - extension of endocervical columnar epithelium
Cervical polyp
Cervical carcinoma
Cervicitis
Vaginitis
Vulval varicosities

Remember that up to 50% of cases of APH, no specific cause is found.

Question 5

What might you look for on examination of a woman who presents with antepartum haemorrhage?

Answer 5

Maternal:
Obs - HR, BP, RR
Pallor
Uterine tenderness
Uterine contractions
Cervical abnormalities on speculum
Cervical change on contraction (through digital examination - ONLY IF PLACENTA PRAEVIA HAS BEEN EXCLUDED)

Fetal:
Lie/presentation/engagement
Auscultation of heart to determine viability

Question 6

Which blood tests must be done in antepartum haemorrhage (7)

Answer 6

Haemoglobin
Group and save / crossmatch
Rhesus status
Coagulation profile
Kleihauer test
U&Es
LFTs

Question 7

What is the Kleihauer test?

Answer 7

Examining the blood film of the mother to look for fetal blood cells and hence determine whether there has been feto-maternal haemorrhage (as seen with placental abruption)

Question 8

What is placenta praevia?

Answer 8

This is when the placenta is wholly or partially attached to the lower uterine segment.

Question 9

How do we grade the level of placenta praevia?

Answer 9

Traditionally this was done by grading I - IV, however minor and major is more often used nowadays.

I - Encroaches the lower segment - minor

II - Reaches the internal os - minor

III - Overlies the internal os - major

IV - Centrally placed in the lower segment

Question 10

What are the risk factors for placenta praevia?

Answer 10

Previous placenta praevia

Previous caesarian section

Advanced maternal age

Multiparity

Multiple pregnancy

Presence of a succenturiate (accessory) placental lobe

Smoking

Question 11

What are the clinical features of placenta praevia?

Answer 11

Painless
Unprovoked
Bright red vaginal bleeding
Absence of labour

Question 12

At what point in gestation does placenta praevia normally present with antepartum haemorrhage?

Answer 12

In the third trimester, from about 32 weeks

Question 13

What would you expect to find on digital examination of a woman with antepartum haemorrhage caused by placenta praevia?

Answer 13

YOU MUST NEVER DO A DIGITAL EXAMINATION OF A WOMAN WITH SUSPECTED PLACENTA PRAEVIA AS THIS CAN PROVOKE MASSIVE BLEEDING

Question 14

What would you expect to find on abdominal examination of a woman with antepartum haemorrhage caused by placenta praevia?

Answer 14

Soft, non tender uterus

Cephalic presentation not engaged

Question 15

At what point in gestation are most cases of placenta praevia diagnosed?

Answer 15

Low lying placenta is normally visible on routine 20 week ultrasound scan. If low lying placenta is noted at this point then follow up in third trimester should be arranged to make diagnosis.

Question 16

How do you manage a patient with placenta praevia?

Answer 16

ABCDE approach

Immediate caesarian section if there is maternal or fetal compromise

Steroids to improve fetal lung maturity

Caesarian section is usually advised if placenta is encroaching within 2 cm of cervical os.

Question 17

What are the complications of placenta praevia?

Answer 17

Increased risk of postpartum haemorrhage

.Placenta accreta - part or all of the placenta remains attatched to the uterus walls because it grows too deep into the uterine wall

Question 18

What is the recurrence rate of placenta praevia?

Answer 18

4-8% with an increased rate of placenta accreta (placental invasion of the myometrium) in each pregnancy.

Question 19

Uterus in placenta previa

Answer 19

Soft and non tender

Question 20

Name two scan that should be done?

Answer 20

CTG

USS