High risk pregnancy: Previous caesarean section

Question 1

How should a decision about VBAC be made?

Answer 1

• maternal priorities,
• a general discussion of the overall risks and benefits of Caesarean section,
• risk of uterine rupture
• perinatal mortality and morbidity.

Question 2

List contraindications for VBAC

Answer 2

• Previous uterine rupture
• Classical caesarean scar
• Major placenta praevia
• Complicated uterine scars (caution, access to previous surgery notes).

Question 3

What factors make a VBAC more likely to be successful ?

Answer 3

• Greater maternal height,
• Maternal age less than 40 years,
• BMI less than 30,
• Gestation of less than 40 weeks
• Infant birth weight less than 4 kg (or similar/lower birth weight to/than index Caesarean delivery)
Spontaneous onset of labour,
Vertex presentation,
Fetal head engagement or a lower station,
Higher admission Bishop score also increase the likelihood of successful VBAC.
• Successful VBAC is more likely among women with prior caesarean for fetal malpresentation (84%).

Question 4

What should you mention when counselling a woman about VBAC?

Answer 4

• Women should be informed that the success rate of planned VBAC is 72–75%.
• Previous vaginal delivery, particularly previous VBAC, is the single best predictor of successful VBAC (85-90%)
• Previous vaginal delivery is also independently associated with a reduced risk of uterine rupture.
Planned VBAC is associated with an approximately one in 200 (0.5%) risk of uterine rupture.
• Absolute risk of birth-related perinatal death associated with VBAC is extremely low and comparable to the risk for nulliparous women in labour.

Question 5

ERCS risks

Answer 5

(ERCS) is associated with a small increased risk of • Placentapraeviaand/oraccretapelvic
• Adhesions
• The risk of perinatal death with ERCS is extremely low,
• Small increase in neonatal respiratory morbidity when ERCS is performed before 39 weeks gestation ( can be reduced by steroids)

Question 6

How should a VBAC be managed?

Answer 6

• CTG from commencement of regular uterine contractions.
• In induced and/or augmented labour compared with spontaneous
VBAC labour
2-3 fold increased risk of uterine rupture
1.5-fold increased risk of caesarean delivery in induced and/or augmented labour compared with spontaneous VBAC labour.
• Mechanical methods of induction (amniotomy or Foley catheter) is associated with a lower risk of scar rupture compared with induction using prostaglandin