Birth After Caesarean (VBAC)
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Direct answer
Seven of ten properly selected women attempting vaginal birth after caesarean (VBAC, the outcome of trial of labour after caesarean, TOLAC) succeed — 60-80 per cent, highest with a prior vaginal birth and spontaneous labour — and successful VBAC beats repeat caesarean on every maternal measure: less haemorrhage and infection, faster recovery, fewer placental complications later. Selection is the whole game: one previous lower-segment transverse scar for a non-recurrent indication, no contraindication to vaginal birth, interdelivery interval beyond 18-24 months. Rupture threatens about 0.5 per cent of trials, so labour demands continuous monitoring, intravenous access, immediately available theatre — and prostaglandin induction, above all misoprostol, is contraindicated.
What you must remember
- Terminology: TOLAC is the attempt, VBAC the success; the success rate of a well-selected trial is 60-80 per cent, and a woman who has vaginally birthed after a caesarean before reaches 85-90 per cent.
- Absolute contraindications: previous classical or T-shaped incision, prior uterine rupture, transfundal surgery such as a myomectomy entering the cavity, and standard contraindications to vaginal birth (major placenta praevia, transverse lie, gross cephalopelvic disproportion).
- Rupture numbers: unscarred uterus about 1 in 10,000; one lower-segment transverse scar in spontaneous labour about 0.5 per cent; misoprostol induction multiplies this several-fold and is forbidden; oxytocin augmentation is permitted with monitoring but raises risk modestly.
- Warning signs in labour: foetal bradycardia is the commonest first sign; also loss of station, abnormal trace, scar-site pain (unreliable under epidural), vaginal bleeding, haematuria — any one triggers a category-1 caesarean.
- Interval matters: conception within 12-18 months of the caesarean (interdelivery under 18-24 months) multiplies rupture and dehiscence risk — a key counselling number where spacing is short.
- Predictors of failure: recurrent indication (previous caesarean for dystocia), body mass index above 30, birthweight above 4000 g, induction rather than spontaneous labour, and advanced maternal age.
- Documented counselling: the written plan — attempted VBAC versus elective repeat caesarean with its own risks (accreta spectrum climbing with each subsequent scar, placenta praevia, adhesions, longer recovery) — is the medicolegal spine of management.
A trial of labour, hour by hour
A 28-year-old with one prior lower-segment caesarean for breech presents in spontaneous labour at 39 weeks; interdelivery interval 3 years, foetus estimated 3.2 kg — an ideal candidate who has consented in writing with rupture risk quantified. On admission: intravenous cannula, blood group and save, continuous cardiotocograph, and a labour ward where theatre and anaesthesia are genuinely available within minutes. Labour is charted on the partogram; oxytocin is used only for clear hypotonic contractions, at conservative doses, with the trace reviewed each escalation. The second stage is limited — a generous threshold for assisted delivery rather than prolonged pushing over a scar. At 6 cm the foetal heart drops to 70 and stays there: the sequence is rehearsed — call, transfer, general anaesthesia if regional is not sited, laparotomy — and a 4 cm dehiscence at the scar edge is repaired; the baby is born depressed but resuscitates well. That is the rare failure mode handled well; the commoner story is an uneventful vaginal birth, discharge in two days, and a uterus that keeps its options open.
The Indian VBAC paradox
India presents a paradox: a high-caesarean environment on one side (repeat caesareans being the largest contributor to institutional rates) and a genuinely underused VBAC option on the other. Private obstetrics, defensively, widely practises "once a caesarean, always a caesarean" — Craigin's 1916 aphorism that evidence retired decades ago — while government and teaching hospitals, squeezed for beds and theatres, often encourage TOLAC and carry most of the country's experience. The practical constraints an examiner expects: 24-hour anaesthesia and theatre cover cannot be assumed at many first-level units, so TOLAC must be planned where backup genuinely exists; short birth spacing is common, and the under-24-month interval flags a higher-risk scar; and previous-incision records are often missing in unbooked women — a classical scar presenting as "previous caesarean, details unknown" deserves imaging review and a low threshold for repeat section. FOGSI guidance endorses VBAC in selected women, aligning with RCOG and NICE.
Frequently asked questions
What is the expected success rate of a well-selected TOLAC?
Sixty to eighty per cent overall, rising to 85-90 per cent in women with a previous vaginal birth or previous successful VBAC.
What are the absolute contraindications to TOLAC?
Previous classical or T-shaped uterine incision, prior rupture, transfundal myomectomy or other cavity-entering uterine surgery, and current contraindications to vaginal delivery.
Why is misoprostol contraindicated with a uterine scar?
It causes intense, tetanic uterine activity that multiplies scar rupture risk several-fold; cervical ripening in a scarred uterus, when needed, favours a mechanical balloon.
What is the earliest sign of scar rupture in labour?
Foetal bradycardia on the cardiotocograph — pain and scar tenderness are unreliable, especially with epidural analgesia in place.
How does birth interval affect rupture risk?
Conceiving within about 12-18 months of the caesarean (interdelivery interval under 18-24 months) substantially increases rupture and dehiscence risk, making spacing a core part of VBAC counselling.