# Trial of Labour After Caesarean

> TOLAC and VBAC for FMGE Obstetrics: candidate selection, rupture risk, banned drugs, intrapartum signs of rupture and success rates.

- Canonical URL: https://prepelephant.com/topics/fmge/obstetrics-and-gynaecology/trial-of-labour-after-caesarean
- Exam / course: FMGE · Subject: Obstetrics and Gynaecology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Trial of Labour After Caesarean", PrepElephant, https://prepelephant.com/topics/fmge/obstetrics-and-gynaecology/trial-of-labour-after-caesarean

## 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.