Birth after caesarean — structured SAQ (15 marks)

(a) Absolute contraindications (3 marks)

One mark for each of the first three; the fourth earns credit if the first three are present. ^[1]

• Previous classical or inverted-T uterine incision.^[1]
• Previous uterine rupture.^[1]
• Any other contraindication to labour — for example placenta praevia, vasa praevia or a transverse lie.^[1]
• Her informed refusal after counselling. Consent runs both ways.^[1]

Applied to this woman: none applies. Her scar is documented as an uncomplicated lower segment transverse incision closed in two layers, her interdelivery interval is 31 months, and the pregnancy is otherwise uncomplicated. She is a good candidate for planned vaginal birth after caesarean.^[1][2]

(b) Quantifying success and rupture (4 marks)

Success (2 marks): ^[2][3]

• Overall about 72 to 75 per cent of women who plan a VBAC achieve one; 74 per cent in the derivation cohort of 11,687 women for the current prediction model.^[3]
• A validated calculator individualises this using maternal age, pre-pregnancy weight, height, indication for the previous caesarean, obstetric history and medication-treated chronic hypertension; its area under the curve is 0.75.^[3]
• Her specific modifiers: no previous vaginal birth and a previous caesarean for arrest of dilatation both lower her predicted chance; a normal body mass index range, an interval over 24 months and an anticipated spontaneous labour raise it.^[3][2]

Rupture (2 marks) — quote at least two sources: ^[2][4][9]

• About 1 in 200 (0.5 per cent); symptomatic rupture occurred in 0.7 per cent of 17,898 women undergoing a trial of labour in the largest prospective cohort.^[2]
• UK national data: 2.1 per 1000 maternities in women with a previous caesarean planning vaginal birth versus 0.3 per 1000 planning elective repeat caesarean.^[9]
• Consequence: hypoxic-ischaemic encephalopathy followed rupture in 0.46 per 1000 women at term undergoing a trial of labour, including two neonatal deaths in that cohort; 370 elective caesareans would be needed to prevent one symptomatic rupture.^[2][4]
• The Australian dataset: in 2345 women across 14 Australian hospitals, the composite of fetal or infant death or serious infant outcome was 2.4 per cent with planned VBAC versus 0.9 per cent with planned elective repeat caesarean (relative risk 0.39, number needed to treat 66), and major haemorrhage 2.3 versus 0.8 per cent.^[5]
• The other side: repeated caesareans raise placenta accreta risk, which with a praevia runs 3, 11, 40, 61 and 67 per cent by number of previous caesareans — relevant if she wants more children.^[10]

(c) Intrapartum requirements to document (3 marks)

• Birth in a unit with immediate access to caesarean birth, an anaesthetist, blood and a neonatal team.^[1]
• Continuous electronic fetal monitoring from established labour, because an abnormal fetal heart rate is the earliest and often the only sign of rupture.^[1][8]
• Intravenous access and a group and hold on admission.^[1]
• One-to-one midwifery care, hourly progress review, and deliberate assessment for scar tenderness documented at each review.^[8]
• A named escalation plan: who is called, and the point at which slow progress becomes a caesarean rather than more oxytocin.^[7]
• Epidural analgesia may be offered — it does not mask the sentinel sign, which is the fetal heart rate.^[1][8]

(d) Induction at 41+2 weeks (3 marks)

• State the trade-off plainly (1 mark): induction both lowers her chance of a vaginal birth and raises her risk of scar rupture, so it needs a consultant decision and explicit consent.^[1][6]
• Quantify it (1 mark): rupture occurred at 1.6 per 1000 with repeat caesarean and no labour, 5.2 per 1000 with spontaneous labour, 7.7 per 1000 with induction without prostaglandin, and 24.5 per 1000 with prostaglandin-induced labour.^[6]
• Method (1 mark): prefer mechanical cervical ripening and amniotomy; avoid prostaglandin; use oxytocin sparingly, since exposure at any dose was associated with rupture in a 5201-woman analysis and no upper safe threshold could be identified.^[6][7]
• Offer the alternative: elective repeat caesarean, and if she chooses it, at 39 weeks or later — she is already beyond that, so it can be scheduled promptly.^[1]

(e) Signs of scar rupture, in order (2 marks)

1. Abnormal fetal heart rate — the commonest and often the only early sign.^[8]
2. Scar pain persisting between contractions, including breakthrough pain through a working epidural.^[8]
3. Fresh vaginal bleeding or frank haematuria.^[8]
4. Loss of station — the presenting part recedes on examination.^[8]
5. Cessation or change in the pattern of contractions.^[8]
6. Maternal tachycardia, hypotension and collapse — a late finding.^[8][9]