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1. Purpose
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According to the Consultative Council on Obstetric and Paediatric Mortality and Morbidity1 in Victoria the caesarean section rate has been steadily increasing in public hospitals statewide from 21% in 2000 to 27% in 2005.
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The most common indications for caesarean section are previous caesarean section, dystocia, malpresentation and non-reassuring fetal status2.
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Vaginal birth after caesarean section (VBAC) should be considered as an option for all women who present for prenatal care with a history of previous caesarean birth. Where contraindications exist, a repeat caesarean section will be advised, but in the majority of cases successful vaginal birth can be achieved safely for both mother and baby2.
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The success rate of VBAC ranges from 55% to 85%3. Predictors of successful VBAC include:
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- Non-recurring indication of caesarean section (eg malpresentation)2
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- Pregnancy induced hypertension2
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- Institutions in which success rates are high2
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- Onset of labour is spontaneous2
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It is essential women make an informed choice regarding whether to attempt a vaginal birth or whether to plan another caesarean Section. Therefore, these guidelines recommend that obstetricians and women discuss the risks and benefits of VBAC (reinforced by the provision of appropriate literature) to plan the birth.
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2. Definition of terms
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Vaginal Birth After Caesarean Section (VBAC)
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3. Antenatal Management
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3.1 Obtain essential background information
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- Obtain the previous caesarean section operative report to determine the type of uterine incision used. Where unobtainable, access and review information concerning the circumstances of the previous delivery to determine the likelihood of a low transverse incision. Where the likelihood of a lower transverse incision is high, VBAC should be offered after additional counselling2.
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- Document on the Women's VBAC Antenatal Assessment form - background information and information about last caesarean section (including previous uterine scar)2.
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3.2 Establish eligibility for VBAC
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Step 1 Review the Women's VBAC Antenatal Assessment form and previous operative report.
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Step 2 Ascertain whether any of the following contraindications for VBAC are present:
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- Previous classic caesarean section birth2,4
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- Some uterine surgery (e.g. hysterotomy, deep myomectomy, cornual resection and metroplasty)2,4
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- Previous uterine rupture or dehiscence2,4
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- There is a maternal or fetal reason for elective caesarean section in the current pregnancy2,4
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- If there is multiple gestation2 or suspected fetal macrosomia2 these may be contraindications to VBAC. It is essential that the obstetrician undertakes additional assessment to ascertain whether VBAC is contraindicated for this individual.
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Note: Women who have had 2 or more LSCS are encouraged to have a repeat elective caesarean section. Those women who want a VBAC must be offered appointments with an obstetrician at (or prior to) 26 weeks gestation for discussion, and 36 weeks gestation for final discussion and decision.
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Step 3 Confirm eligibility. A woman is eligible for VBAC where:
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- No contraindications are apparent, and
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- She has had 1 previous transverse low-segment caesarean section.
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Step 4 The obstetrician must document in the Women's Antenatal Obstetric Assessment for VBAC the outcome of the eligibility assessment.
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3.3 Discuss birth options
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All women should be informed of the birth options available to them.
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The obstetrician should:
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- Base discussion around the evidence-based “Birth Choices” VBAC decision aid.
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- Explain to women ineligible for VBAC why this is the case.
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- Ask and actively listen to the woman’s experiences, knowledge and expectations.
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- Acknowledge to women that this is a complex issue.
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- Establish whether the woman wants to be involved in decision making about the mode of birth.
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- Where women are eligible for VBAC the obstetrician will explain the maternal and perinatal risks and benefits of VBAC and elective caesarean section2 and a balanced discussion of the uncertainties.
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- Additional information should be provided to:
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| - Women who have had more than one previous caesarean.
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|  | - Women giving birth less than 24 months of a caesarean section
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| | - Women with multiple gestation2 or suspected fetal macrosomia2 who, after additional assessment, are considered eligible for VBAC.
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The obstetrician must document in the Women's VBAC Antenatal Assessment form that:
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- The woman’s eligibility for VBAC has been discussed with the woman, including the rationale behind the decision
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- The woman has been informed of the birth options available to her
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- The woman has been provided with information regarding the risks and benefits of each
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- A balanced discussion of the uncertainties has been undertaken
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- Decision aids / other information have been provided to the woman, and
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- The decision regarding agreed / preferred mode of birth.
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Where the woman elects for a VBAC, the obstetrician will discuss and document a management plan for labour.
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3.4 Obtain acknowledgement from the woman
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The obstetrician will must ensure that the final section of the Women's VBAC Antenatal Assessment form is completed i.e. that the woman acknowledges the discussion about birth options.
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3.5 Specific guidelines for VBAC induction of labour
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Where a woman is planning a VBAC and requires induction of labour, the following must be considered when deciding on the birth plan:
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- Induction with prostaglandin E2 (dinoprostone) is associated with an increased risk of uterine rupture and should not be used except in rare circumstances after appropriate counseling2.
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- Induction of labour with oxytocin in combination with amniotomy (or confirmation of ruptured membranes) may be associated with an increased risk of uterine rupture and should only be used carefully after appropriate counseling. When administered, consideration should be given to reducing the rate of syntocinon infusion once labour is clearly established2. (See CPG for Induction of Labour)
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- A mechanical cervical ripening device (e.g. Atad catheter or Foley catheter) may be used safely to ripen the cervix in a woman planning a VBAC2.
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- Misoprostol used for 2nd Trimester termination of pregnancy should be used with caution in a woman with a uterine scar given the higher risk of uterine rupture2.
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4. Notes
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Refer to the Women's CPG: Vaginal Birth After Caesarean Section: Intrapartum management
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5. References
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1. The Consultative Council on Obstetric and Paediatric Mortality and Morbidity, Hospital Profile of Perinatal Data, Royal Women’s Hospital (2005).
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2. Society of Obstetricians and Gynaecologists of Canada (SOGC) Clinical Practice Guidelines: Guidelines for Vaginal Birth After Previous Caesarean Birth (2005).
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3. Dodd JM, Crowther CA, Huertas E, Guise JM, Horey D. Planned elective repeat caesarean section versus planned vaginal birth for women with a previous caesarean birth. The Cochrane Database of Systematic Reviews (2004), Issue 4.
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4. Institute for Clinical Systems Improvement (ICSI) Health Care Guideline Vaginal Birth After Cesarean (2004).
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Evidence table
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2 August 2007
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Royal Women's Hospital Clinical Practice Guidelines (CPGs) are intended to provide guidance to health care professionals, based on a thorough evaluation of research evidence, on the practical assessment and management of specific clinical issues or situations. The guidelines allow some flexibility on the part of the health care professional based on the needs of the specific patient for whom they are caring.
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