Laboured spontaneously in the past
Pre-eclampsia
Fetal macrosomia
Dilatation at which it took place
Operative notes – any extensions or incisions such as J or T
Inter-pregnancy interval
Gestation at which caesarean section took place
Condition requiring likely induction of labour, e.g. gestational diabetes
Multiple pregnancy
Fetal macrosomia
Pre-eclampsia
Motivation for a particular mode of delivery
Future fertility plans/plans for size of family
Attitude towards risk
This information aids the clinician in counselling the woman about her individual risks associated with either trial of vaginal birth after caesarean section (VBAC) or planned elective lower-segment caesarean section (LSCS). All necessary information may not be immediately available at the first visit; however, the clinician should make reasonable efforts to obtain it, such as writing to the unit where the previous section took place if elsewhere.3
It is also essential to take into account the woman’s own preferences, her plans for future pregnancies, her perception of risk and her motivation for a particular type of birth.3,4 Recommendation or advice on future deliveries after the caesarean section may have been made immediately after the previous section, and it can be helpful to ask whether the woman remembers any such discussion or advice being given.
Although the counselling process should begin early in the woman’s pregnancy, ideally in the first trimester, definite plans may need to be delayed until the third trimester. Factors that alter the recommended mode of delivery can develop after the booking visit: for example, whether the current pregnancy is singleton or multiple, the location of the placenta in relation to the previous scar, because of the increased risk of placenta praevia and accreta with a scarred uterus,3 and development of conditions such as pre-eclampsia or gestational diabetes that may require early delivery or potential induction of labour. Pre-eclampsia is also associated with a reduction in the success of VBAC.3
Many units offer women a more detailed discussion of birth after caesarean section with specialist midwives in the form of individual counselling or group workshops (‘VBAC workshops’). This may also provide an opportunity for the woman and her partner to explore any concerns they have regarding the future birth in a more informal environment, and it can help them to make a decision they feel most comfortable with.
The final decision is usually made in the third trimester at the antenatal clinic by the woman and her clinician. This should be clearly documented in the notes: both her handheld and the hospital notes. There also needs to be an agreed and documented plan should she go into labour or rupture her membranes prior to the date of any planned caesarean section, a plan for any induction if necessary and how an induction would be undertaken, and whether prostaglandins may be used or not.4
Morbidly adherent placenta
Placenta praevia appears to be more common after a caesarean section.3 If identified on ultrasound scan at 20 weeks, especially if the placenta is anterior, a repeat scan for placental localization should be arranged at 32 weeks. This leaves enough time for further investigations such as a Doppler ultrasound or MRI scan (depending on the unit’s guidelines and experience of the local radiologists) to be performed if the placenta remains anterior and low-lying, to exclude or identify a placenta accreta or percreta and put in place the necessary arrangements for delivery, for example involvement of interventional radiologists or urologists.
Options for birth after previous caesarean section
Two options for delivery exist for women who have had a previous caesarean section:
trial of vaginal birth
planned (elective) repeat caesarean section
A Cochrane review first published in 2004 and updated in 2013 concluded that at present each option has its own risks and benefits, and the evidence available to aid women and those caring for them in future pregnancies is from non-randomized sources that may be subject to bias.5 This can lead to problems in counselling women, with the advice based on suboptimal evidence.
Some authors argue that comparing the outcomes of VBAC or repeat emergency caesarean section after a trial of labour with those after planned elective section is inappropriate, because most complications in the trial of labour group occur in the women whose VBAC is unsuccessful.2
When discussing risks associated with either option, it is important to consider the woman’s understanding and attitude towards risk.4 Clinicians should also ensure when counselling these women that their own preferences and perception of risk do not bias or ‘lead’ the patient into making a choice that she may not feel comfortable with.
Vaginal birth after caesarean section (VBAC)
Historically, women who were delivered by caesarean section were told that all future deliveries also needed to be by caesarean section.2 However, medical opinion began to change in the 1970s and vaginal birth after caesarean section (VBAC) started to be offered to selected women. More recently reports of complications, such as uterine rupture associated with VBAC, led to a rise again in repeat section.2 Today, after extensive reviews of the available evidence by bodies such as the Royal College of Obstetricians and Gynaecologists (RCOG),3 the American College of Obstetricians and Gynecologists (ACOG),2 the National Institute for Health and Care Excellence (NICE)4 and the Cochrane Collaboration,5 and the drive by the WHO to try to reduce rates of caesarean section worldwide,1 VBAC has again become a safe choice for many women who have had one or two previous caesarean sections.
Overall success rate for VBAC quoted by the RCOG, NICE and ACOG is between 60% and 90%, with multiple factors significantly influencing an individual’s chance of success (Table 6.2).2–4
| Factors for successful VBAC | Factors against successful VBAC |
|---|---|
| Previous vaginal birth (87–90% chance of successful VBAC) Spontaneous labour Indication for previous caesarean was elective for breech presentation | Previous caesarean section(s) indication was for labour dystocia Increased maternal age Non-white ethnicity No previous vaginal birth Over 40 weeks gestation Maternal obesity Short stature Male infant Pre-eclampsia Short inter-pregnancy interval (< 2 years) Neonatal macrosomia (> 4000 g) Augmented or induced labour Previous caesarean section performed at a preterm gestation No epidural analgesia during labour |
Although the Cochrane review identified no level 1 evidence to guide clinicians and women when making decisions regarding mode of delivery after previous caesarean section,5 attempts have been made to devise decision-making aids using scoring systems to quantify the individual probability of a successful VBAC.2,4 These systems use factors such as those in Table 6.2 to give a percentage chance of successful outcome for VBAC, and were developed from observational data on the outcomes of deliveries after previous caesarean sections. There is also some evidence, from a further observational study using one of these scoring systems, that women with less than a 60% chance of a successful VBAC have a higher rate of morbidity than those undergoing a planned elective section.2
Contraindications to VBAC
Women who have previously had a classical caesarean section should be advised that it is recommended they have a repeat elective caesarean section due to the higher risk of uterine rupture (2–9%) if the incision was a high vertical incision along the complete length of the body of the uterus. The risk of rupture for low vertical incisions and those who have had ‘J-shaped’ or ‘inverted T’ incision in the lower segment also have a higher risk of rupture of approximately 2%.3
Myomectomy and other complex uterine surgery may also lead to higher rates of uterine rupture, although data regarding the specific risks are lacking.3 Advice should be sought if possible from the surgeon who performed the uterine surgery.
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