VBAC

Question 1

What is the success rate of VBAC?

Answer 1

72-75%

Question 2

How does success rate of VBAC change in subsequent pregnancies?

Answer 2

Increased no. successful VBACs = greater success rate of future VBAC

Question 3

What is the single best predictor of successful VBAC?

Answer 3

Previous successful VBAC

Question 4

Give 5 maternal and fetal factors increasing chance of successful VBAC

Answer 4

Greater maternal height
Maternal age <40y
BMI < 30
Gestation < 40w
Infant birthweight of < 4kg

Question 5

Give 3 obstetric indicators of more likely successful VBAC

Answer 5

Spontaneous onset of labour
Fetal head engagement or a lower station
Higher admission Bishop score

Question 6

Give 4 risk factors for unsuccessful VBAC

Answer 6

Induced labour
No previous vaginal delivery
BMI >30
Previous caesarean for labour dystocia

Question 7

What is the risk of VBAC?

Answer 7

1/200 risk of uterine scar rupture

Question 8

In which women is VBAC offered?

Answer 8

singleton pregnancies of cephalic presentation at 37w or
beyond
Who have had a single previous lower segment caesarean delivery

Question 9

List 6 advantages of VBAC

Answer 9

Quicker recovery

Less risk of DVT + PE

Less abdominal pain after birth

Avoids the complications of surgery + anaesthesia

Greater chance of an uncomplicated normal vaginal
delivery next time

Caring for the baby is easier as not recovering from an operation

Question 10

Give 3 disadvantages of VBAC

Answer 10

Chance of uterine rupture 1 in 200

Higher chance of emergency C/S

Potential risks to mother + baby from emergency procedure

Question 11

Give 3 advantages of elective C/S

Answer 11

Planned procedure with set date for delivery

Virtually no risk of uterine rupture

Avoids the risks of labour + risks of emergency C/S

Question 12

Give 4 disadvantages of elective C/S

Answer 12

Surgical procedure, may be longer than 1st due to scar tissue forming. Can also make the surgery more difficult + increase risk of damage to bladder + bowel.

Higher risk of a DVT + PE

Longer recovery than a vaginal delivery

Increase chances of praevia/ accreta spectrum

Question 13

Give 3 relative contraindications to VBAC

Answer 13

> ,2 previous C-sections

Need for IOL

Previous labour outcome suggestive of cephalopelvic disproportion

Question 14

In which women is VBAC absolutely contraindicated?

Answer 14

Previous uterine rupture

Classical caesarean scar

If other absolute CI to vaginal birth that apply irrespective of a scar (e.g. placenta praevia).

Question 15

How should VBAC be managed in labour?

Answer 15

IV access, FBC, G+S
Regional anaesthesia
Continuous foetal monitoring
Clear plan on assessment of labour progress
Awareness of signs of scar rupture

Question 16

What are the risks in VBAC if induction is needed?

Answer 16

2-3 fold increased risk of uterine rupture
Risk lower with mechanical (amniotomy/ Foley catheter) IOL than prostaglandins

Question 17

Give 5 signs of uterine rupture

Answer 17

Abnormal CTG

Severe abdo pain, esp. if persisting between contractions

Acute onset scar tenderness

Abnormal PV bleeding

Haematuria