Caesarean Section — Indications, Robson Classification, Skin and Uterine Incisions, and VBAC

A caesarean section (CS) is delivery of the fetus through an abdominal incision (laparotomy) and a uterine incision (hysterotomy). It is done when vaginal birth carries greater risk to the mother or baby — either because a complication arises during labour or because a condition prevents vaginal delivery altogether.

Rates have climbed steeply. WHO estimates that caesarean section rose from about 7% of births in 1990 to 21% by 2021, with nearly 29% projected by 2030. In five countries caesareans already outnumber vaginal births. In the United States the rate went from 5% in 1970 to about 32% in 2022.

Indications are traditionally grouped as maternal, uterine/anatomic (placental) and fetal. Most are relative — the decision depends on the clinical picture — but a few make vaginal delivery unsafe almost by definition.

There is no absolute medical contraindication to caesarean section when an emergency demands immediate delivery — lack of ideal anaesthesia, antibiotics or equipment does not forbid it. The one firm limit is ethical: a competent patient who refuses the operation cannot be operated on. Severe coagulopathy, extensive previous abdominal surgery or a dead or previable fetus make caesarean less preferable (relative contraindications).

In 2015 WHO proposed the Robson classification (the 10-group classification) as the global standard for assessing, monitoring and comparing caesarean rates within and between facilities. Every woman admitted for delivery falls into one of 10 groups that are mutually exclusive and totally inclusive. The groups are built from obstetric variables already recorded in every labour ward: parity, number of fetuses, previous caesarean, onset of labour, gestational age and fetal presentation.

The abdomen can be opened through a suprapubic transverse or a midline vertical incision. The midline is favoured when speed or wide access matters.

At term the lower uterine segment is thin and relatively avascular, so a low transverse (Kerr) incision — the lower segment caesarean section (LSCS) — is used for most caesareans. Compared with a classical incision it causes less bleeding, is easier to repair and produces fewer adhesions, and its scar is far less likely to rupture in later labour.

A low transverse incision can be extended if more room is needed, creating a J, U or inverted-T incision. Because these extensions cut into the contractile upper segment, a woman with a prior T or J incision is treated like one with a classical scar — planned repeat caesarean, no trial of labour.

• Antibiotic prophylaxis before skin incision, not after cord clamping — it reduces post-caesarean infection by 60–70%.
• Cefazolin single IV dose: 1 g if < 80 kg, 2 g if ≥ 80 kg, and up to 3 g if ≥ 120 kg. Adding azithromycin 500 mg IV helps women operated after labour or membrane rupture.
• Aspiration prophylaxis: sodium citrate plus an H₂ blocker; left lateral tilt with a wedge to prevent aortocaval compression.
• Hair removal only if it improves the view — with clippers, not razors. Vaginal cleansing before a caesarean in labour reduced endometritis from 8.7% to 3.8% in one study.
• Close the subcutaneous layer if it is ≥ 2 cm thick (fewer haematomas, seromas and wound separations).

Trial of labour after caesarean (TOLAC) is a planned attempt at vaginal birth; a successful one is a vaginal birth after caesarean (VBAC). Overall 60–80% of women who attempt TOLAC deliver vaginally. Successful VBAC avoids surgical recovery and lowers the risks of further caesareans (adhesions, accreta).

• Spontaneous labour is preferred — it gives higher success and lower rupture risk.
• If induction is needed: prostaglandins (misoprostol, dinoprostone) are avoided for cervical ripening because they raise rupture risk; low-dose oxytocin or a transcervical balloon can be used.
• Continuous electronic fetal monitoring throughout labour.
• VBAC calculators (e.g. the MFMU Network calculator) estimate success but do not replace individual assessment; clinical pelvimetry is a poor predictor.

The commonest sign of rupture is an abnormal fetal heart rate tracing, seen in about 70% of cases (often sudden prolonged bradycardia). Others are a change in contraction pattern, pain out of proportion to labour, sudden loss of fetal station, vaginal bleeding and haematuria (blood in the catheter bag). Rupture is an emergency requiring immediate laparotomy; transfusion and sometimes hysterectomy may be needed.