VBAC

Question 1

What is the chance of a successful VBAC?

Answer 1

60-80%

RANZCOG Guideline

Question 2

What are factors that favour a successful VBAC?

Answer 2

Previous safe vaginal birth
Previous successful VBAC
Spontaneous onset of labour
Uncomplicated pregnancy without other risk factors

Question 3

What are factors that reduce the likelihood of a successful VBAC?

Answer 3

Previous CS for dystocia
IOL
Co-existing fetal, placental or maternal conditions
Maternal BMI > 30
Fetal macrosomia >4kg
AMA
Short stature
More than one previous CS
Risk factors associated with an increased risk of uterine rupture

Question 4

What is the chance of a successful VBAC in a woman that has had a previous vaginal birth?

Answer 4

87-91%

Question 5

What is the incidence of scar rupture in a patient undergoing VBAC?

Answer 5

5-7:1000

RANZCOG guideline

Question 6

What is the risk of uterine rupture associated with previous classical CS?

Answer 6

20-90:1000

Question 7

What is the risk of uterine rupture associated with previous T or J incisions?

Answer 7

19:1000

Question 8

What are the symptoms and signs of uterine rupture?

Answer 8

Abnormal CTG (present n 55-87% cases)
Severe abdominal pain especially persisting between contractions
Chest pain or shoulder tip pain
Sudden onset of shortness of breath
Acute onset of scar tenderness
Abnormal vaginal bleeding or haematuria
Cessation of previously efficient uterine activity
Maternal tachycardia, hypotension or shock
Loss of station of the presenting part

Question 9

What are the benefits of a successful VBAC?

Answer 9

Less maternal morbidity for index pregnancy and future pregnancies
Avoidance of major surgery and multiple CS in future pregnancies
Earlier mobilisation and discharge from hospital
Patient gratification in achieving vaginal birth if this is desired

Question 10

What are the risks of a VBAC?

Answer 10

Increased perinatal loss compared with ERCS at 39/40 (1.8 per 1000 pregnancies)
HIE risk (0.7 per 1000)
- related to labour and vaginal birth and to scar rupture
Increase morbidity of EmCS compared to ElCS if unsuccessful VBAC
Pelvic floor trauma

Question 11

What are the benefits of an ERCS?

Answer 11

Avoid late stillbirth (after 39 weeks)
Reduced perinatal mortality and morbidity (especially HIE) related to labour, delivery and scar rupture
Reduced maternal risks associated when compared with EmCS
Avoidance of trauma to the maternal pelvic floor
Convenience of planned date for birth

Question 12

What are the risks of ERCS?

Answer 12

Surgical morbidity and complications Both with index pregnancy and further pregnancies (including praevia, accreta)
Increased risk of neonatal respiratory morbidity - TTN, RDS, pulmonary HTN
Lower rates of initiating breastfeeding

Question 13

With attempted VBAC, what is the risk of perinatal death?

Answer 13

0.4-0.7/1000

A further 1.4 (to total 1.8) may be expected to have an antenatal, intrapartum or neonatal death after 39 weeks gestation
It is appropriate that this increase in perinatal mortality be acknowledged
- even though mostly not a direct consequence of uterine rupture

Question 14

With attempted VBAC, what is the risk of maternal death?

Answer 14

0.02/1000

Question 15

With attempted VBAC, what is the risk of hysterectomy?

Answer 15

0.5-2/1000

Question 16

With attempted VBAC, what is the risk of HIE?

Answer 16

0.4/1000

Question 17

As the number of CS increases, there is a statistically significant increase in the risk of…

Answer 17

Severe haemorrhage (requiring >4u RBC)
Hysterectomy
Bladder injury
Bowel injury

And placenta praevia + accreta

Question 18

What is the increase in the risk of uterine rupture with a pregnancy interval less than 18-24 months, following CS

Answer 18

2-3 x increase

Question 19

With BMI > 40, what is the risk of uterine rupture / dehiscence

Answer 19

2%

Prospective observational study of >14,000 patients

Question 20

How often should a woman having a TOLAC have VEs?

Answer 20

Q4h

After 7cm, q2 hourly to detect a secondary arrest of labour

Question 21

What are the rates of
- successful vaginal birth
- uterine rupture
In V2BACs compared to V1BAC

Answer 21

• successful vaginal birth: 71% vs 77%
• uterine rupture: 1.6% vs 0.7%
  BUT multivariate analysis of NICHD showed no sig diff rates in rupture

RCOG states that if a patient has been fully informed by a Consultant Obstetrician, they may be suitable

Question 22

How does epidural affect the success rate of VBAC?

Answer 22

Success rate:

• With epidural: 70%
• Without epidural: 50%

Question 23

What are the contraindications to VBAC?

Answer 23

• Previous uterine rupture
• Previous classical/vertical uterine incision
• Any contraindication to vaginal delivery: praevia, footling breech etc.