Vaginal birth after caesarean section (VBAC) - risks of rupture and RCOG recommendations

The RCOG Each Baby Counts programme’s recent report into the anaesthetic care which contributed to the serious brain injury, neonatal death and stillbirths suffered by 49 babies in 2015 highlights some of the highest risk areas in maternity patient safety. Aside from the essential teamwork, communication and forward planning which is needed to handle the multiple, time-sensitive, emergencies which occur in maternity units, the report emphasised that trial of vaginal birth after a previous caesarean (VBAC), if incorrectly counselled, undertaken and managed can result in uterine rupture, severely brain damaging the fetus and threatening the life of mother and baby. 

Serious injury was caused to a baby when signs of uterine rupture (including maternal tachycardia, breakthrough pain between contractions and a worrying CTG trace) were missed during a trial of VBAC labour. Despite these warning signs, the mother was incorrectly given syntocinon, a uterine stimulant, increasing the stress on her uterine scar. The report reiterated that pain breaking through a previously effective epidural in a woman with a history of uterine surgery must always trigger an obstetric review for scar rupture.

What are the risks of VBAC compared with a planned repeat caesarean section (ERCS)?

Assuming that delivery takes place at or after 39 weeks gestation in circumstances suitable for VBAC:

  • Planned VBAC has a 1 in 200 (0.5%) risk of uterine rupture, compared with 2 in 10 000 (0.02%) in a previously unscarred uterus. The risk increases when VBAC delivery is induced or labour is augmented with syntocinon.
  • The success rate for planned VBAC is 72-75% but increases if the mother has had a previous vaginal or successful VBAC delivery. If VBAC delivery is successful, it has fewer complications than ERCS.
  • Unsuccessful VBAC resulting in emergency caesarean section carries the greatest risk of adverse outcome.
  • The risk of unsuccessful VBAC and caesarean section increases if VBAC labour is induced or augmented.

Who is suitable for VBAC?

The RCOG guidelines for VBAC list the circumstances most suited to VBAC:

  • Singleton pregnancy (i.e. expecting one baby)
  • Cephalic presentation (baby is head down)
  • Pregnancy at 37 weeks or more
  • Single previous LSCS (lower segment caesarean section - scar across the lower part of the abdomen)

A successful VBAC delivery is more likely where the mother is taller, younger than 40, and has a BMI below 30, and the labour starts spontaneously before 40 weeks, and the baby is in vertex presentation with a birthweight below 4kg.

The risk of uterine rupture during VBAC increases with the mother’s age and the baby’s gestation and size, and where the mother’s last delivery took place less than 12 months previously.

Who can’t have a planned VBAC delivery?

Planned VBAC is contraindicated where there is:

  • A history of uterine rupture
  • Previous classical caesarean scar (scar goes vertically up the middle of the mother’s abdomen)
  • Placenta praevia (i.e. the placenta’s position would obstruct a vaginal delivery)
  • The mother has a history of other uterine surgery

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

The choice of delivery mode must be agreed by the mother and a senior obstetrician, based on her personal risk factors, before the planned date of delivery and after she has been counselled about the risks and the circumstances in which a trial of VBAC would be abandoned and caesarean section needed. All antenatal counselling must be documented in the medical records. If ERCS is planned, an agreed contingency plan for early spontaneous labour must be written in the records.

What additional safety measures are in place during VBAC delivery?

Labour must take place in a delivery suite equipped for continuous intrapartum care and monitoring, with facilities for immediate caesarean delivery and advanced neonatal resuscitation. The fetal heart must be continuously monitored electronically from onset of regular contractions throughout the VBAC, to ensure early detection of maternal or fetal compromise, obstructed labour or uterine scar rupture. The mother’s condition and progress of labour must be regularly monitored by one-to-one care.

What are the clinical signs of uterine rupture in labour?

The three classic signs of uterine rupture are pain, vaginal bleeding and fetal heart-rate abnormalities, but in 48% of all cases the scar breaks down without any maternal symptoms and is diagnosed later during surgery.

Clinical signs associated with uterine rupture include:

  • Abnormal CTG (most common sign)
  • Severe abdominal pain, particularly if the pain persists between contractions
  • Sudden scar tenderness
  • Abnormal vaginal bleeding
  • Haematuria (blood in the urine)
  • Previously efficient contractions stop 
  • Maternal tachycardia (elevated heart rate), hypotension (low blood pressure), fainting or shock
  • There is a change in abdominal shape and fetal heart-rate not detected at the previous transducer site
  • The fetus is no longer presenting properly

Suspected rupture of the uterine scar is an emergency requiring urgent caesarean section and neonatal resuscitation as the unborn baby is deprived of oxygen, leading to permanent brain damage or death.

As specialists in birth trauma claims, Boyes Turner’s medical negligence team are experienced in helping mothers and babies affected by uterine rupture during inappropriately counselled or managed VBAC deliveries.  

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

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