Trial of Labour After Caesarean
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Direct answer
One prior lower-segment transverse caesarean is not a lifelong sentence to repeat surgery: a properly selected woman offered a trial of labour after caesarean (TOLAC) achieves vaginal birth after caesarean (VBAC) in roughly 60-80 per cent of attempts, against a symptomatic uterine rupture risk commonly quoted near 0.5 per cent with a low transverse scar. Eligibility asks for one previous lower-segment transverse incision, a clinically adequate pelvis, no other contraindication to vaginal birth, spontaneous or favourable labour, and — non-negotiable — a hospital able to begin an emergency caesarean within about 30 minutes with blood and anaesthesia on site. Prostaglandin ripening and misoprostol are avoided with a scarred uterus, oxytocin is used cautiously, and the earliest reliable sign of rupture is a fetal heart rate abnormality, not pain.
What you must remember
- Good candidate: one prior lower-segment transverse caesarean, vertex presentation, no prior classical or T-shaped incision, no prior rupture, inter-delivery interval above 18-24 months, spontaneous labour, estimated fetal weight under about 4 kg.
- Success figures: VBAC succeeds in roughly 60-80 per cent of trials; a prior vaginal birth is the strongest predictor of success.
- Rupture risk by scar: lower-segment transverse about 0.5 per cent in labour; classical or inverted-T scars (5-10 per cent or higher) are absolute contraindications to labour — elective repeat caesarean before labour.
- Drugs with the scar: misoprostol is contraindicated for cervical ripening or induction with a previous caesarean; oxytocin augmentation is permitted with careful titration and continuous monitoring (hyperstimulation lowers the safety margin).
- Rupture — earliest sign: fetal bradycardia or prolonged decelerations on the trace precede the classical abdominal pain, scar tenderness, loss of station, vaginal bleeding, haematuria or hypotension; cessation of previously effective contractions is another clue.
- Labour conduct: continuous electronic fetal monitoring, intravenous access, crossmatched blood available, signed consent covering both outcomes, and a low threshold for abandoning the trial — failed TOLAC is a caesarean, not a defeat.
- Counselling numbers for the viva: elective repeat caesarean carries its own risks (placenta praevia and accreta in future pregnancies rise with each additional scar), which is the strongest long-term argument for TOLAC in young Indian grand multipara-to-be families.
Counselling a candidate for TOLAC, step by step
Sit with a 27-year-old whose first caesarean was for fetal distress at 8 centimetres two years ago. The first step is record retrieval: the scar type decides everything — a lower-segment transverse incision documented, and the door to TOLAC opens; a classical scar closes it permanently. Step two scores her odds: a non-recurrent indication (fetal distress, breech) and progress to 8 centimetres last time predict success above 80 per cent, while a diagnosis of cephalopelvic disproportion at 5 centimetres predicts failure and a third-trimester assessment of fetal size matters.
Step three is the consent conversation in numbers: attempted VBAC succeeds about three times in four; rupture with a transverse scar happens in about 1 in 200 trials and, when it does, an immediate caesarean with possible hysterectomy follows; a planned repeat caesarean trades that risk for surgical morbidity now and placental problems in future pregnancies. Step four sets the labour rules: she labours in a unit with 24-hour obstetrics, anaesthesia and theatre; monitoring is continuous; oxytocin, if needed, is titrated low; prostaglandins are off the table. Step five is the abandonment threshold — an abnormal trace, or progress that stalls in the active phase — triggers caesarean without persistence, because the trial is a plan, not a promise.
The trap in the vignette
NBE builds the rupture question around the fetal heart, not the abdomen: a TOLAC patient whose trace drops to 70 beats per minute with loss of variability and a stationary head after amniotomy is a ruptured uterus until proven otherwise — the answer is immediate laparotomy, never "observation" or "stop oxytocin and recheck in an hour". Second trap: inter-delivery interval under 18 months with a prior caesarean raises rupture risk and steers toward repeat surgery. Third: the drug question — the single agent most forbidden in TOLAC induction is misoprostol; candidates who choose it because "it is the WHO agent" lose the mark.
Frequently asked questions
What is the success rate of VBAC in a well-selected candidate?
Roughly 60-80 per cent, highest when the prior caesarean was for a non-recurrent indication and the woman has previously delivered vaginally.
Which drug is contraindicated for induction in a woman with a previous caesarean?
Misoprostol — it causes hyperstimulation and markedly raises scar rupture risk; cervical ripening, if required at all, uses mechanical methods cautiously.
What is the earliest sign of uterine rupture during TOLAC?
An abnormal fetal heart rate pattern, typically prolonged bradycardia or deep variable decelerations, preceding abdominal pain, tenderness or haemodynamic collapse.
Why is a previous classical caesarean an absolute contraindication to labour?
The upper-segment incision ruptures far more often in labour (commonly quoted around 5-10 per cent or higher), so delivery is by elective repeat caesarean before labour onset.
What inter-delivery interval increases rupture risk?
Conception within about 6 months and inter-delivery intervals shorter than 18-24 months are associated with higher rupture risk and poorer TOLAC outcomes.