Birth after Caesarian Section

50% of women will attempt a VBAC and 50% will be successful.

Factors associated with successful VBAC-a previous vaginal birth, especially previous VBAC, are associated with 87% to 90% BVAC success.

Risk factors associated with unsuccessful VBAC are:

a. Induced labour
b. No previous vaginal birth
c. BMI greater than 30
d. Previous caesarian section for dystocia

When all of these are present successful VBAC is less than 40%.

Other factors associated with a decreased likelihood of VBAC:

a. VABC at or after 41 weeks
b. Birth weight greater than 4kg
c. No epidural anesthesia
d. Previous pre-term caesarian birth
e. Cervical dilatation at admission less than 4cm
f. Less than 2 years from previous caesarian birth
g. Advanced maternal age
h. Non white ethnicity
i. Short stature
j. Male infant

Contra indication to VBAC:

a. Previous uterine rupture
b. Previous high vertical classical caesarian section, 2-9% risk of uterine rupture
c. 3 or more previous caesarian sections.

No significant difference in the rate of uterine rupture in VBAC with 2 or more previous caesars but hysterectomy rate x 3 transfusion requirements x 2.

Specific risks of VBAC:

a. Rupture rate 0.2 – 0.7%
b. No risk of rupture with ERCS, uterine rupture in an unscarred uterus is 0.005 – 0.02%

Blood Transfusion 10.7% 1%
Endometritis 2.9% 1.8%
Hysterectomy 0.23% 0.30%
Thrombosis 0.04% 0.06%
Maternal Death 17/10 to the five 44/10 to the five

The increased risk of successful verses unsuccessful VBAC.

Uterine rupture 2.31% 0.11%
Uterine dehiscence 2.0% 0.14%
Hysterectomy 0.46% 0.14%
Transfusion 3.2% 1.2%
Endometritis 7.6% 1.2%

Women considering a planned VBAC have a 2-3 out of 10,000 additional risk of birth related perinatal death when compared to ERCS. This is equivalent to a first delivery.

Perinatal mortality 0.32% 0.13%
Still birth greater than 37 weeks 0.19% 0.08%
Delivery related perinatal death 0.04% 0.14%
Respiratory distress symptom 2-3% 3-4%

VBAC carries an 8/10,000 risk of baby developing HIE. Approximately 50% of the increased risk is caused by uterine rupture.

The risks of ERCS. There are minimal risks for a 2nd or 3rd caesarian section but risk increases with the number of caesarian sections.

a. Placenta accreta
b. Injury to bladder, bowel or ureter
c. Ileus
d. The need for post operative ventilation
e. ICU admission
f. Hysterectomy
g. Blood transfusion requiring more than 4 units
h. The duration of operative time and hospital stay

Number of previous C/S Hysterectomy Rate Placenta Accreta Accreta with Placenta Previa Bladder Injury Transfusion Requirement
1 0.65% 0.24% 3%
2 0.42% 0.13% 11% 0.3% 7.2%
3 0.9% 0.57% 40% 0.8% 7.9%
4 2.41% 2.13% 61% 14.1%
5 3.49% 2.33% 67% 2.4%
6 or more 8.99% 6.74% 67%