# Anaesthetic Choice for Caesarean Section

> Anaesthesia for caesarean section in NEET-PG Obstetrics and Gynaecology: spinal technique, hypotension management, epidural top-up and GA indications.

- Canonical URL: https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/anaesthetic-choice-caesarean
- Exam / course: NEET-PG · 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: "Anaesthetic Choice for Caesarean Section", PrepElephant, https://prepelephant.com/topics/neet-pg/obstetrics-and-gynaecology/anaesthetic-choice-caesarean

## Direct answer

Spinal anaesthesia is the technique of choice for caesarean section: a single intrathecal injection of hyperbaric bupivacaine (commonly 10-12.5 mg) with an opioid such as fentanyl (10-25 micrograms) or diamorphine produces a block to at least the T4-T6 sensory level within minutes, keeps the mother awake for delivery, avoids the airway and its obstetric-specific dangers — failed intubation and pulmonary aspiration — and improves neonatal condition compared with general anaesthesia in most settings. Hypotension, its chief physiological toll, is prevented and treated with left uterine displacement, co-loaded intravenous fluid, and phenylephrine (50-100 microgram boluses or an infusion), the current vasopressor of choice for fetal acid-base neutrality. Epidural top-up serves women with a working labour epidural; general anaesthesia is reserved for profound fetal compromise, contraindications to neuraxial block such as coagulopathy or frank sepsis with shock, and urgency where no block exists.

## What you must remember

- **Spinal recipe:** hyperbaric bupivacaine 0.5%, 10-12.5 mg (about 2-2.5 mL), plus fentanyl 10-25 micrograms or diamorphine 300 micrograms; target sensory level T4-T6 (to the nipple or sternum); onset 2-5 minutes; duration roughly 2-3 hours.
- **Why awake beats asleep:** the pregnant airway is difficult (oedema, full dentition), ventilation is harder (low functional residual capacity), and aspiration risk is high (Mendelson syndrome) — failed intubation runs of the order of 1 in 300-500, many-fold above the general theatre.
- **Hypotension protocol:** block to sympathectomy plus aortocaval compression drop vascular tone — prophylaxis with at least 15 degrees of left tilt or manual displacement, crystalloid co-load, and phenylephrine 50-100 micrograms titrated to maintain systolic pressure near baseline; ephedrine (tachycardia, fetal acidosis with repeated doses) is second line.
- **High spinal and total spinal:** ascending block above T4 with respiratory embarrassment — recognise bradycardia, hypotension and dyspnoea; treat with airway support, vasopressors and fluids; it follows excessive dose or barbotage, and must be distinguished from hypotension alone.
- **Epidural top-up:** for an existing labour epidural, urgent conversion with 10-20 mL of concentrated local anaesthetic (lidocaine 2% with adrenaline or bupivacaine 0.5%) in fractionated doses through a tested catheter, with a test dose to exclude intravascular or intrathecal placement.
- **General anaesthesia technique:** rapid sequence induction with cricoid pressure, propofol (moderated in shock or severe pre-eclampsia), and succinylcholine 1-1.5 mg/kg, whose short duration suits the difficult airway.
- **Neuraxial contraindications:** patient refusal, coagulopathy (platelets commonly below about 75-80 × 10^9/L in pre-eclampsia protocols), sepsis, and hypovolaemic shock until resuscitated.
- **Pre-eclampsia angle:** neuraxial is preferred if platelets permit (avoids pressor surges of laryngoscopy); general anaesthesia in pre-eclampsia risks hypertensive crisis at intubation — blunted with agents such as magnesium continuation, opioids or short-acting antihypertensives before induction.

## A decision walk-through

An elective caesarean at 39 weeks in a healthy woman: spinal in the sitting or lateral position at L3-L4, hyperbaric bupivacaine 12 mg with fentanyl, laid supine with left tilt, co-loaded with a litre of crystalloid, phenylephrine infusion running to hold systolic pressure — delivery within 15 minutes of the block, neonate vigorous, mother's partner present. Now the same day's emergency: a term woman with an epidural that has worked well through labour needs a category-2 caesarean for arrest — top up the tested catheter in fractionated doses, aspirating between aliquots. Then the category-1 crash for cord prolapse with no block: preoxygenase, rapid sequence induction with cricoid pressure, incision within minutes — the failed-intubation drill is rehearsed beforehand, never improvised.

Finally, the severe pre-eclampsia case with platelets of 95,000: neuraxial stands, general anaesthesia doubles the intubation-pressor risk — the choice of technique is a risk-benefit arithmetic performed for every single case.

## Where students slip

Two classic confusions. First, vasopressor choice: phenylephrine is first line for spinal hypotension (alpha agonism, reflex bradycardia, fetal acid-base neutral), while ephedrine crosses the placenta and repeated doses acidify the fetus — an old teaching reversed by modern trials that candidates still get backwards. Second, the level: a block to T10 (umbilicus) is inadequate for caesarean — intra-abdominal traction and peritoneal pain demand T4-T6; examiners ask "what level?" expecting "nipple/T4-T6". The third, subtler slip is calling general anaesthesia safer for the fetus: apart from true profound compromise where minute-level speed matters, awake regional anaesthesia delivers better neonatal acid-base status and immediate skin-to-skin contact — the default answer is spinal.

## Frequently asked questions

### Which anaesthetic technique is standard for elective caesarean section?

Spinal anaesthesia — hyperbaric bupivacaine 10-12.5 mg with an intrathecal opioid, targeting a T4-T6 sensory level with the mother awake.

### How is spinal hypotension managed?

Left uterine displacement, crystalloid co-load, and titrated phenylephrine 50-100 micrograms (or infusion) to maintain baseline systolic pressure, with ephedrine as second line.

### When is epidural top-up used instead of a spinal?

When a functioning labour epidural exists — urgent conversion with fractionated concentrated local anaesthetic through a tested catheter saves the time and risk of a fresh spinal.

### Which conditions force general anaesthesia for caesarean?

Patient refusal of neuraxial block, coagulopathy or thrombocytopenia below threshold, sepsis with shock, profound hypovolaemia, and category-1 urgency without an existing block.

### Why is the obstetric airway dangerous under general anaesthesia?

Airway oedema and full dentition make intubation harder, functional residual capacity is low, and aspiration risk is high — failed intubation is several-fold commoner than in general surgery.