VAGINAL DELIVERY AFTER PAST SECTION

1. Is once a section always a
section?
VBAC & BEYOND
Dr. Kavinda Hewawitharana

2. Definition
Planned attempt to deliver vaginally
by a woman who had a previous
cesarean delivery regardless of its
outcome(3)

3. Why VBAC is important?
• Reduce morbidity & mortality of mother plus reduce complicated
future pregnancies
placenta previa risk 1%-1 LSCS, 1.7% -2 LSCS, 2.8%-3LSCS
Accreta risk in 11-14% of previa with past 1 CS, 23-40% of previa
with 2 CS & about 67% in previa with >5 CS deliveries
• Reduce morbidity and mortality of neonates-TTN
• Country’s health economics by reducing surgical expenses

4. Epidemiology & Statistics
• Main reason to avoid VBAC was fear for legal issues
according to 2010,NIH consensus development
conference
• Over the years number of VBAC increased upto28.3%
by 1996 and LSCS rate reduced to 20%
• With this complications also increased in number.
• But with legal issues again VBAC rate dropped to
8.5% and CS rate increased up to 31.1%
• No proper multicenter data available to asses how Sri
Lankan health system is effective in VBAC

5. What is the likelihood of VBAC
success?
• Differences in VBAC success rates between centers
and published studies
• consideration should be given to counselling women
using locally derived VBAC success rates given the
pragmatic differences in population, induction/non-
induction VBAC policies and healthcare provision
Eg-72-75% in metanalysis
Australian cohort trials -59%

6. • 85-90% success if one vaginal birth after
previous cesarean delivery exist
• Unsuccessful VBAC likely if
Induction
No previous vaginal births
BMI>30
Past labour dystocia lead CS
*if all above present-only 40% success rate

7. Cont.
• VBAC & ERCS are associated with maternal &
neonatal complications.
• VBAC has fewer complications than ERCS
• But most maternal complications occurs when
its need to do CS for TOLAC failed pts.
• This is even more if scar dehesion or rupture
occurs

8. Maternal risk from ERCS Vs VBAC in term patients
(ACOG 184/2017)
Maternal Risk ERCD in past 1 section(%) VBAC(%)
Infections 3.2 4.6
Surgical injury 0.3-0.6 0.37-1.3
Blood transfusion 0.46 0.66
Hysterectomy 0.16 0.14
Uterine Rupture 0.02 0.71
Maternal Deaths 0.0096 0.0019

9. Neonatal Morbidity from ERCS Vs VBAC
(ACOG184/2017)
Neonatal Risk ERCD (%) VBAC(%)
Antepartum stillbirths 0.21 0.10
Intrapartum stillbirths 0-0.004 0.01-0.04
HIE 0-0.32 0-0.89
Perinatal mortality 0.05 0.13
Neonatal mortality 0.06 0.11
NICU 1.05-17.6 0.8-26.2
Respiratory Morbidity 2.5 5.4
TTN 4.2 3.6

10. ANC assessment of VBAC pts
• Routine care recommended by NICE
• Review previous uterine surgical detail and
indication-detail of past cesarean & concerns in
past pregnancy
• If there is past successful VBAC,chance for
successful subsequent safe VBAC increased and
it’s one of the most positive factor for VBAC(85%)
• Look for any contraindication for vaginal delivery
in present pregnancy

11. When to discuss birth plan in past
section patients
• By member of maternity team soon after the mid
trimester scan assuming no contraindication to VBAC
• Involve obstetrician if
contraindications noted
patient is not certain of MOD
insists ERCS
request induction(>41 weeks)
pregnancy related complications(PIH/Breech/FGR or
macrosomia)
MOD finalized by 36 weeks

12. Cont.
• Discuss about advantages and disadvantages
of both ERCS and VBAC during counseling
• Worth to tell about facts and figures,
likelihood of successful VBAC ect.

13. Indications
• Singleton
• Cephalic
• 37 week or beyond
• Single past cesarean section with lower
segment incision
Planned VBAC are safe
(2)

14. Contraindications
• Past uterine rupture(5% or higher risk of
recurrent rupture)
• Classical scar
• Other absolute contraindications(eg-placenta
previa)
Other complicated uterine scars should be
assesed and decision should be taken by
senior VOG

15. Types of scars & its impact
• Classical scar
10 times likely to rupture and also even before labour
begins when compare with lower segment transverse
incision (1)
so by the time patients reach hospital this will be lethal
for both mother and fetus
3-5% rupture rate is noted with this type of incision

16. cont.
• Lower segment transverse incision
rupture after some hours of labour onset so
considerable time left to intervene.
but if inverted T or single or dual J extensions
present, Consider as classical incision.

17. Cont.
• Myomectomy scars
needs to asses individually. If too extensive &
opened into uterine cavity these patients are
best not to subjected to labour(1)
Unless deep myometrial excision or accidental
perforation ,even after hysteroscopy, VBAC
can be considered.
but care should be taken to manage them like
a VBAC

18. • Hysterostomy
These scars also should be considered as classical
scars and VBAC are avoided.
***
Past scar rupture of any variety is an absolute
contraindication for VBAC
mostly these scars complicated VBACs related data
are insufficient to draw conclusions on safety of
scar types.

19. Does scar thickness matter?
• Third trimester USS of lower uterine segment
• Very thin lower segments are associated with
increased risk of uterine scar rupture.
Rosenberg et al Eur J Obstet Gynecol 1999;87
Martins WP et al Ultrasound Obstet Gynecol
2009;33 vol

20. Ultrasound Obstet Gynecol 2013;42:132–9
• measurement of lower uterine segment (LUS) thickness
antenatally in could be used to predict the occurrence of a
uterine defect (scar dehiscence or scar rupture) in women
undergoing VBAC.
• myometrial thickness (the minimum thickness overlying the
amniotic cavity at the level of the uterine scar) cut-off of 2.1–4.0
mm provided a strong negative predictive value for the
occurrence of a uterine defect during VBAC
• whereas a myometrial thickness cut-off between 0.6 and 2.0
mm provided a strong positive predictive value for the
occurrence of a uterine defect.
• However, the study could not define an ideal LUS thickness cut-
off value usable in clinical practice. This meta-analysis provides
support for the use of antenatal LUS measurements in the
prediction of a uterine defect in women undergoing VBAC;
however, clinical applicability needs be assessed in prospective
observational studies using a standardized method of
measurement.

21. Can we Induce/Augment VBACs? (1)
• Spontaneous is the most desirable
• Induction is should only be considered if
indication is compelling
• If cervix is favorable, amniotomy is the
method of choice & no additional risk to
spontaneous labour
• But if this fails,oxytocin may cautiously use
and this will only slightly increase uterine
rupture
Eur J Obstet Gynecol 1999;87

22. Cont.
• If cervix is unfavorable and prostaglandins use
risk of scar rupture increase
• It is highest with misoprostol but also
significantly high with Dinoprostone
• So misoprostol should not be used and if PGE2
use, there should be preparation for EM/CS
• Intra cervical balloon catheters to ripen cervix
and other mechanical methods can be used.

23. Cochrane 2016 August 31
• 8 studies reviewed and design problems are
noted
• 7 out of 8 are open studies and since low
quality with low evidence can not be certain
about evidence on which induction method is
appropriate

24. Cont.
• But inductions/augmentations are associated
with
2-3 fold increase rupture
1.5% increases in CS

25. ERCS vs. Elective induction of Labour
• According to Cochrane database there is no
RCT that compares these two though small
scale studies conducted in local facilities.
• These are not sufficient enough to give as
information to women under going VBAC
• This signifies unbiased RCT requirement
• If ERCS plan, it is better after 39 weeks and
about 10% will come with pain before this. So
better to keep organize delivery plan early

26. • By delaying from 38 to 39 weeks, about 5% of
TTN is reduced.
• But this delay may increase about 0.05% of
still births

27. Intra partum care in VBAC
• Center with access for EM/CS
• Epidural can use. But increasing demand of
analgesia rises suspicion on uterine rupture. This
delay labour and increase instrumental deliveries.
• Continuous CTG
• One to one care,FBC,DT & regular monitoring of
patient
• Regular( not less than 4 hrs.) cervicometric
progress

28. Clinical features associated with
uterine scar rupture
• abnormal CTG
• severe abdominal pain, especially if persisting between
contractions
• acute onset scar tenderness
• abnormal vaginal bleeding
• hematuria
• cessation of previously efficient uterine activity
• maternal tachycardia,
• hypotension, fainting or shock
• loss of station of the presenting part
• change in abdominal contour and inability to pick up fetal
heart rate at the old transducer site.

29. Factors associated with increased risk
of uterine rupture
• Inter delivery gap<12 months
• Post dates
• Maternal age >40 Years
• Obesity
• Low pre labour bishop score
• Macrosomia(>4kg)
• Reduced USS lower segment thickness

30. Inter delivery Gap
• A recent retrospective study involving 3176 patients
evaluated the safety of women undergoing VBAC with
a short inter-delivery interval. The study concluded
that a short inter-delivery interval (less than 12
months) is not a risk factor for major complications
such as uterine rupture and maternal death, but that it
is for preterm delivery. Further data are needed before
the safety of such an approach can be confirmed
Kessous R, Sheiner E. Is there an association between short interval from previous cesarean section and
adverse obstetric and perinatal outcome? J Matern Fetal Neonatal Med 2013;26:1003–6.

31. • Abnormal cardiotocography (CTG) is the most
consistent finding in uterine rupture and is present
in 66–76% of these events.
• But over 50% cases present with combination like
pain and CTG issues
• Most uterine ruptures (more than 90%) occur
during labour (the peak incidence being at 4–5 cm
cervical dilatation), with around 18% occurring in the
second stage of labour and 8% being identified post
vaginal delivery.
• Early diagnosis of uterine scar dehiscence or rupture
followed by expeditious laparotomy and neonatal
resuscitation are essential to reduce associated
morbidity and mortality.

32. • An observational study indicated a potential
upper limit for nonhypoxic neonatal delivery of
18 minutes from suspected uterine rupture to
delivery.
• It is important to note that scar dehiscence
may be asymptomatic in up to 48% of patients
• Classical triad of uterine rupture may present in
less than 10% cases(pain,PV bleeding
abnormalities)
Uterine rupture with attempted vaginal birth after cesarean delivery: decision-to-
delivery time and neonatal outcome. Obstet Gynecol 2012;119:725–31
. Signs, symptoms and complications of complete and partial uterine ruptures during
pregnancy and delivery. Eur J Obstet Gynecol Reprod Biol 2014;179:130–4.

33. VBACs for past 2 or more sections
• Risk of uterine rupture is double though there
are number of successful vaginal deliveries
after past 2 CS (1)
Bretalle F et al,Eur J Obstet Gynecol Reprod Biol
2001;94 volume
These patients can subjected to VBAC after
discussion and counseling by senior VOG (2)

34. REFERENCES
• (1)Operative Obstetrics by Munro Kerrs-
2014.(12th edition)
• (2)GTG 45-2015 October
• (3)ACOG practice bulletin 184-2017 November
• (4)Cochrane database