Labour After Previous Caesarean Delivery

Labour after previous caesarean delivery is labour in a woman with one or two earlier caesarean sections, in which the uterine scar is stressed by contractions. With a low transverse scar, planned vaginal birth after caesarean succeeds in most women, and uterine rupture is uncommon. It matters because vaginal birth avoids repeat surgery, but rupture is an emergency, so care must be in a facility able to do emergency caesarean section within 30 minutes.

• Risk factors for failure or rupture: induction with prostaglandins, oxytocin augmentation, interval below 18 months, previous classical or T shaped scar, two or more scars, birth weight above 4000 g, previous failure to progress.
• Spontaneous labour carries the lowest risk.
• A previous vaginal birth raises the chance of success.

Women have normal labour symptoms. Warning signs of rupture are scar pain, tenderness, abnormal fetal heart rate, loss of contractions and vaginal bleeding.

• Scar tenderness persisting between contractions.
• Sudden fetal heart rate abnormality is the commonest sign of rupture.
• Differential diagnosis: normal labour pain, scar dehiscence, uterine rupture, placental abruption, uterine hyperstimulation, urinary infection.
• Complications: uterine rupture, scar dehiscence, haemorrhage, fetal hypoxia, hysterectomy, bladder injury, repeat caesarean section, neonatal death, maternal death.

The approach is to assess suitability for labour in the antenatal period and monitor closely during labour.

• Review the operation record: type of incision (low transverse is suitable; classical or T shaped is not), indication, number of scars, complications, interval since last caesarean.
• Ultrasound for placental site (exclude previa and accreta), estimated fetal weight, lie and scar thickness (lower segment below 2.3 mm in late pregnancy is a concern).
• Continuous cardiotocography from admission; pulse, blood pressure and contraction pattern.
• Haemoglobin, group and cross-match.

The principle is to offer planned vaginal birth to suitable women in a capable facility, with continuous monitoring and rapid access to caesarean section.

• Supportive: counselling on success rates and risks; birth in a unit able to do caesarean section within 30 minutes with anaesthetic cover and blood; IV access; continuous cardiotocography; early epidural is acceptable; avoid prolonged labour.
• Pharmacological: avoid misoprostol and dinoprostone; oxytocin 10 IU in 1 litre Ringer's lactate (10 mU/mL) started at 6 mL per hour (1 mU/minute) and increased by 6 mL per hour (1 mU/minute) every 30 minutes to a maximum of 120 mL per hour (20 mU/minute) with senior review, only when contractions are inadequate and the scar is a low transverse scar; cefazolin 2 g IV as a single dose before caesarean section; oxytocin 10 IU IM after birth, then 20 IU in 1 litre at 125 mL per hour for 4 hours; tranexamic acid 1 g IV over 10 minutes if bleeding exceeds 500 mL; enoxaparin 40 mg subcutaneous daily for 10 days after repeat caesarean section in women with moderate risk of thrombosis.
• Procedures: spontaneous labour awaited to 41 weeks; induction by Foley catheter with a 30 mL balloon or amniotomy when needed, with oxytocin only after senior review; planned repeat caesarean section at 39 weeks for women who choose it, and for a previous classical scar (36 to 37 weeks), placenta previa, previous rupture, three or more scars or a contraindication to labour; emergency caesarean section for suspected rupture or fetal compromise.
• Special groups: previous classical or T shaped incision, previous uterine rupture, or placenta previa are contraindications to labour; twin pregnancy with one earlier low transverse scar may labour in selected women.
• Red flags: scar pain or tenderness, fetal bradycardia or late decelerations, loss of contractions, vaginal bleeding, haematuria, sudden shock, recession of the presenting part.
• Follow-up: observe for bleeding for 2 hours then 4-hourly for 24 hours; document the labour for the next birth; review at 6 weeks; contraception and an interval of at least 18 months.