VBAC (Vaginal birth after caesarean section) - what are the risks?

When a pregnant woman is advised to have a vaginal delivery after her previous child was born by  caesarean section, she must be properly advised and her labour carefully managed to reduce her risk of uterine rupture.

The Royal College of Obstetricians and Gynaecologists (RCOG) has published guidelines setting out maternity safety measures which must be followed when planning or delivering a baby by VBAC. These safety measures include careful counselling about delivery choices, planning, resourcing and management of labour and delivery.

Where a mother who is having a VBAC delivery is poorly advised, or her labour and delivery are incorrectly managed, she risks uterine rupture, and death or brain injury (such as cerebral palsy) to her baby.

What is uterine rupture?

Tearing (rupture) of the mother’s uterus (womb) or breakdown (dehiscence) of a previous caesarean scar during labour or delivery is life-threatening for the mother and the baby. When the uterus tears, the blood and oxygen supply to the unborn baby is interrupted, resulting in brain damage and disability, or death.

The severe blood loss (haemorrhage) which follows uterine rupture is also life-threatening to the mother. Life- saving surgery may involve a hysterectomy, which will prevent her from having further children. Even without a hysterectomy, the damage to her uterus might affect her future pregnancies.

Which is more risky after caesarean section - VBAC or planned repeat caesarean section (ERCS)?

For deliveries from 39 weeks of pregnancy, where the circumstances are safe for VBAC:

• The risk of rupture is 0.5% or 1-in-200 for a planned VBAC compared with 0.02% or 2-in-10,000 for vaginal delivery where the mother has an unscarred uterus. The risks of rupture in a VBAC delivery go up further if labour is induced or Syntocinon is used;
• 72-75% of planned VBACs are successful. The VBAC is more likely to succeed if the mother has had a vaginal delivery or successful VBAC delivery in the past;
• Successful VBAC deliveries have fewer complications than ERCS;
• The biggest risk of poor outcome is where VBAC is unsuccessful and results in emergency caesarean section;
• Unsuccessful VBAC and caesarean section is more likely where VBAC labour is induced or augmented (boosted) with Syntocinon.

Who is suitable for VBAC?

The RCOG guidelines for VBAC say that the best circumstances for a VBAC delivery are:

• singleton pregnancy (one baby);
• cephalic presentation (baby head down);
• birth takes place at 37 weeks or later in pregnancy;
• single previous lower segment caesarean section (LSCS) scar across the lower part of the abdomen.

VBAC delivery is more likely to succeed where:

• the mother is taller;
• the mother is younger than 40;
• mother’s BMI is less than 30;
• mother goes into labour spontaneously (not induced) before 40 weeks;
• the baby is in vertex presentation;
• baby weighs below 4kg at birth.

The risk of uterine rupture during VBAC goes up with the mother’s age and as the pregnancy gets nearer to term or the baby gets bigger. The risk is also higher where the woman’s previous delivery was less than 12 months before.

Who shouldn’t have a planned VBAC delivery?

Planned VBAC is contraindicated (must not take place) where:

• the mother has had a previous uterine rupture;
• the mother has a previous classical caesarean scar which runs vertically up the middle of her  abdomen;
• the placenta’s position would obstruct a vaginal delivery, known as placenta praevia;
• the mother has had previous surgery on her uterus.

Who decides whether the delivery will be by VBAC or ERCS?

The RCOG guidelines for safe VBAC state that the decision about the type of delivery:

• must be discussed and agreed by a senior obstetric doctor and the mother;
• must take into account the mother’s risk factors;
• must take place before the planned delivery date;
• must be made after the mother has been counselled by the senior doctor about the risks of VBAC and the circumstances in which a trial of VBAC would be stopped and a caesarean section take place;
• must be documented in the medical records (including all antenatal counselling).

Where the agreed plan is to have a caesarean section (ERCS), the doctor and the mother must plan what will happen if the mother goes into labour early. This contingency plan must be documented in the mother’s medical records.

What safety measures must be in place during VBAC delivery?

Trial of VBAC labour must take place in a fully equipped delivery suite which can provide continuous care and monitoring. The delivery suite must also have facilities to carry out immediate caesarean delivery and advanced neonatal resuscitation.

The fetal heart rate must be continuously monitored electronically from the onset of regular contractions throughout the labour and delivery. Continuous electronic fetal heart monitoring (by CTG) allows maternity staff to spot signs of maternal or fetal deterioration quickly. It is essential during VBAC labour that action can be taken urgently if labour appears obstructed or the mother’s uterine scar begins to break down. The mother’s condition and the progress of her labour must be regularly monitored by one-to-one care.

What is hyperstimulation of the uterus and how is it caused?

Drugs such as the synthetic oxytocin hormone drug, Syntocinon, are sometimes used to induce or stimulate uterine contractions in labour. Syntocinon is a powerful stimulant drug which is administered in very small doses via a drip.

If Syntocinon is used incorrectly, the uterus may contract too frequently or contractions can become too strong. This is known as uterine hyperstimulation, a dangerous condition which can cause uterine rupture.

The fetal heart rate must be continuously monitored electronically whenever Syntocinon is used in labour, so that any deterioration in the mother or baby’s condition is detected as early as possible.

The midwife must monitor the strength and frequency of contractions and reduce or stop the Syntocinon if there are signs of uterine hyperstimulation. Hyperstimulation can cause serious brain damage to the unborn baby, whether or not uterine rupture occurs.

What are the danger signs of uterine rupture in labour?

Pain, vaginal bleeding and fetal heart-rate abnormalities are the three classic signs of uterine rupture but in nearly half of all uterine rupture cases the old scar breaks down without any obvious maternal symptoms. Too often, uterine scar rupture is only noticed later during emergency surgery to deliver the distressed or injured  baby.

Worrying signs in labour which may indicate uterine rupture include:

• abnormalities on the CTG (this is the most common sign);
• maternal severe abdominal pain, often continuing between contractions;
• sudden scar tenderness;
• abnormal vaginal bleeding;
• haematuria (blood in the urine);
• contractions stop after they were previously working well;
• maternal tachycardia (increased heart rate), hypotension (low blood pressure), fainting or shock;
• the shape of the mother’s abdomen changes and the fetal heart rate can no longer be found at the place where the transducer was picking it up;
• the unborn baby is no longer positioned properly for delivery.

Suspected uterine rupture is a medical emergency which must be treated with emergency caesarean section to deliver the baby, and neonatal resuscitation. The baby continues to suffer brain damage from oxygen deprivation until they are born and their oxygen supply is restored.

Boyes Turner’s recent cases relating to VBAC, uterine rupture or hyperstimulation

Boyes Turner’s cerebral palsy and birth injury lawyers regularly secure maximum compensation settlements for severely injured mothers and babies after negligent VBAC, uterine rupture or hyperstimulation.

Our recent cases include:

• £16 million settlement for a child with cerebral palsy after fetal distress in labour was compounded by negligent Syntocinon use and delays in delivery.  
• A very substantial settlement for a child whose cerebral palsy was caused by uterine rupture after CTG monitoring was incorrectly stopped, despite fetal heart-rate and other serious abnormalities, and his mother was left unattended in labour.
• Settlement for a woman who suffered uterine rupture during a VBAC delivery for which she had not given informed consent. After haemorrhage and emergency surgery, incorrect anti-coagulant therapy led to cardiac arrest and neurological damage which has left her in an unconscious, minimally responsive, PVS-like state.  The baby suffered severe brain injuries during the mismanaged labour and sadly died two years later.
• An admission of liability (with damages to be assessed) for a boy with cerebral palsy caused by hypoxic brain injury from excessive use of Syntocinon and hyperstimulation during his mother’s labour. 
• A very substantial settlement for a child with cerebral palsy whose brain was damaged as a result of negligent Syntocinon use, uterine rupture and delays during a mismanaged VBAC delivery. 

If you or your baby have suffered severe injury as a result of medical negligence at birth, contact one of our specialist solicitors by email mednegclaims@boyesturner.com.