Caesarean and instrumental delivery

Question 1

What is the risk of uterine rupture during VBAC?

Answer 1

5-7/1000 women
Of these 1/7 had significant Perinatal morbidity or mortality

If 2 previous CS risk increases 7/1000 to 16/1000

Classical CS - 20-90/1000 risk
T/J incision - 19/1000 risk

2-3 fold increased risk if interpregnancy interval is less than 18 months

Question 2

What is the chance of a vaginal birth when attempting a VBAC?

Answer 2

60-80%

If previous vaginal birth (particularly successful VBAC) highest predator of success - 87-91%

If previous labour dystocia, no previous vaginal births, IOL and BMI >/= 30 - successful VBAC just 40%

NICHD MFMU calculator for predicting successful VBAC- can be useful counselling tool.

Question 3

What factors reduce the likelihood of successful VBAC?

Answer 3

NO prior vaginal birth
High BMI
Previous labour dystocia
LGA
Postdates>41 wks
AMA
Short stature
Fetal malposition

Question 4

What are the main risks of VBAC?

Answer 4

• Increase perinatal mortality (additional 1.8/1000 births - 1.4 due to late stillbirth after 39wks, 0.4 as a result scar rupture)
• Increased HIE (0.9/1000 births)
• Possible EmCS - higher complication rate for mother
• Perineal trauma

Cerebral palsy can be expected to affect approximately 1 in 1000 term births. Of these, only 10% are felt to have an intrapartum origin but a further unknown percentage are the consequence of ‘late antenatal’ events that might be prevented by elective early delivery.

Question 5

What are the main risks of repeat CS?

Answer 5

• Pain
• Bleeding
• Infection
• Damage to bladder/bowel/ureter/blood vessel
• DVT/PE
• Abnormal placentation
  
  • Silver et al. (2006)17 found that placenta accreta was present in 0.24%, 0.31%, 0.57%, 2.1%, 2.3% and 6.7% of women undergoing their first, second, third, fourth, fifth, and sixth or more caesarean deliveries, respectively.
• increasing risk scar rupture (0.7% –> 1.6%)
• Transient tachypnoea of newborn (inversely proportional to gestation, and low risk nr term)
• More difficulty establishing breast feeding

Caesarean delivery may be associated in subsequent pregnancies with delayed conception,
increased risk of ectopic pregnancy, possibly intrauterine growth restriction (IUGR), preterm birth, unexplained stillbirth after 34 weeks. It should be noted
that while relative risks for these complications have been shown to be marginally elevated, the absolute risk increase for many of these complications is extremely small (e.g. for stillbirth the absolute risk increase is 0.03%, giving a number needed to harm of 3,333 women; for ectopic pregnancy the absolute risk increase is 0.1%, giving a number needed to harm of 1000). In
addition, the nature of such studies means it is extremely difficult to account for all possible confounding variables.

Question 6

What is the risk of intracranial injury for different modes of delivery?

Answer 6

CS - 1/2750
NVD - 1/1900
Ventouse - 1/860
Forceps - 1/664

Question 7

How does the risk of maternal morbidity compare between elective and emergency CS?

Answer 7

7% (elective) vs 13.2% (emergency)

Question 8

Considerations for IOL for planned VBAC?

Answer 8

1.4 to 2.45% or 20/1000 risk of uterine rupture when labour has been induced using prostaglandins (i.e roughly 4 times the risk of spontaneous labour).

No increased risk rupture with balloon catheter

Risk with oxytocin 11/1000 (i.e. roughly double the risk in spontaneous labour)

Question 9

What are the RANZCOG categories of caesarean delivery?

Answer 9

Cat 1 - Urgent threat ti life/health of mother or fetus
Cat 2 - Maternal or fetal compromise, but not imminently life threatening
Cat 3 - Needing earlier than planned delivery, but no maternal or fetal compromise
Cat 4 - Planned delivery, at a time acceptable to woman and obstetric team