Spinal anaesthesia for caesarean section

Categories of Caesarean Section

Category	Urgency	Definition	Decision-to-delivery interval	Examples
Category 1	Emergency	Immediate threat to life of woman or fetus	≤ 30 minutes	Acute severe fetal bradycardia, uterine rupture, cord prolapse
Category 2	Urgent	Maternal or fetal compromise not immediately life-threatening	≤ 75 minutes	Suboptimal CTG, severe pre-eclampsia
Category 3	Scheduled (urgent but stable)	No maternal or fetal compromise, but early delivery required	≤ 24 hours	Failed induction of labour, failure to progress
Category 4	Elective	Delivery timed to suit woman and service	Planned (no specific target)	Elective LSCS

Surgical approach

Positioning and prep
- Supine with left uterine displacement (tilt or wedge) to reduce aortocaval compression; arms abducted or tucked; diathermy pad; urinary catheter often after block established
- Skin prep (chlorhexidine/alcohol per local policy), drapes, time-out; prophylactic antibiotics usually before skin incision (local policy may vary)
Incision and entry
- Usually Pfannenstiel transverse skin incision; open rectus sheath; blunt separation of recti; enter peritoneum
- Lower uterine segment transverse incision; delivery of fetus; cord clamped; placenta delivered
After delivery
- Uterotonics (e.g., oxytocin) given; uterine tone assessed; haemostasis; closure of uterus, fascia, skin
- Potential surgical issues affecting anaesthesia: exteriorisation of uterus (pain/nausea), traction on peritoneum, bleeding/atony, need for conversion to GA, hysterectomy in catastrophic haemorrhage

Anaesthetic management (overview)

Type of anaesthesia
- Regional: single-shot spinal is commonest for elective CS; consider CSE for prolonged/complex cases; GA if contraindications, failed neuraxial, or extreme urgency
Duration
- Typical surgical time 30–60 min (longer if adhesions, obesity, placenta accreta spectrum, multiple previous CS); spinal surgical anaesthesia usually ~90–120 min depending on dose and adjuncts
How painful
- Intra-op: should be pain-free; may feel pressure/traction; peritoneal traction and uterine exteriorisation can cause discomfort/nausea
- Post-op: moderate pain; multimodal analgesia required (intrathecal opioid + paracetamol/NSAID)

Aims and required block

Provide rapid, dense surgical anaesthesia with maternal safety and neonatal wellbeing
Target sensory level: T4 (nipple line) to cover peritoneal traction; assess bilaterally with cold/light touch; motor block expected
Maintain uteroplacental perfusion: avoid hypotension, hypoxia, hyperventilation (if GA), and aortocaval compression

Pre-op assessment and preparation

History: urgency category, fasting status, previous neuraxial/GA issues, difficult airway, haemorrhage risk (placenta praevia/accreta, multiple CS), co-morbidities (pre-eclampsia, cardiac disease), anticoagulants/antiplatelets, sepsis/fever, neurological disease
Examination: airway (always), back anatomy, baseline BP, signs of hypovolaemia/bleeding, neuro baseline if relevant
Investigations: Hb/platelets as indicated; group & save/crossmatch depending on haemorrhage risk; consider coagulation if pre-eclampsia/HELLP/anticoagulants
Consent: benefits/risks/alternatives (spinal vs CSE vs GA); specific risks: hypotension, high/total spinal, PDPH, nerve injury, infection, bleeding/epidural haematoma, failure/conversion to GA, pruritus/N&V/resp depression from opioids
Aspiration prophylaxis (local policy): non-particulate antacid ± H2 blocker ± metoclopramide; treat as full stomach especially in emergency
Monitoring and access: standard monitors; left uterine displacement; 1 large-bore IV cannula (consider 2 if haemorrhage risk); vasopressors drawn up and labelled

Contraindications and cautions

Absolute: patient refusal, infection at site, uncorrected hypovolaemia/major haemorrhage, true allergy to LA, raised ICP due to mass lesion, severe coagulopathy/neuraxial haematoma risk
Relative/cautions: sepsis, fixed cardiac output lesions (e.g., severe aortic stenosis), severe pulmonary hypertension, severe thrombocytopenia or evolving coagulopathy, severe fetal compromise where time-to-delivery mandates GA, spinal deformity/previous surgery
Platelets: no single universal threshold; consider trend, cause, bleeding history, and local guideline; involve senior/haematology if uncertainty

Technique: performing the spinal

Position: sitting or lateral; optimise flexion; maintain left uterine displacement as soon as supine
Asepsis: full sterile technique; allow chlorhexidine to dry; sterile gloves, drapes; minimise contamination
Interspace: typically L3/4 or L4/5; midline or paramedian; use pencil-point needle (e.g., 25–27G Whitacre/Sprotte) to reduce PDPH
Drug choice:

Normal height	Heavy marcaine 2.6ml + 400mcg diamorphine
Short height	2.4ml + 300 mcg diamorphine
Placental extraction	Prilocaine 20mg/ml, 2.5-3ml +/- Fentayl 20mcg

After injection:
- Position supine with left uterine displacement;
- Frequent BP monitoring
Block assessment:
- Motor block
- Cold/light touch to T4 bilaterally
- Check sacral sparing; confirm before incision
- Be vigilant for rapid cephalad spread/high spinal symptoms

Physiology and haemodynamics

Pregnancy increases susceptibility to hypotension: aortocaval compression + sympathetic blockade → ↓SVR, ↓venous return, ↓CO; uteroplacental circulation is pressure-dependent (no autoregulation)
Hypotension consequences: maternal nausea/vomiting, dizziness, reduced uteroplacental perfusion → fetal acidaemia if severe/prolonged
Prevention and treatment: left uterine displacement, vasopressor strategy, and fluid co-load (crystalloid at time of spinal) rather than large pre-load

Vasopressors and fluids (practical strategy)

Preferred first-line vasopressor in many UK units: phenylephrine (maintains fetal acid-base; may reduce maternal HR/CO). Alternatives: metaraminol; ephedrine (more fetal acidosis association)
Phenylephrine dosing examples (local protocols vary): prophylactic infusion (e.g., 25–50 micrograms/min) titrated to maintain SBP near baseline; or boluses 50–100 micrograms for hypotension
Metaraminol: bolus 0.25–0.5 mg IV titrated; infusion strategies exist; useful if bradycardic hypotension or phenylephrine causes problematic bradycardia
Ephedrine: bolus 3–6 mg IV; consider if hypotension with bradycardia and concern about uterine blood flow, but be aware of fetal acidosis association
Fluids: crystalloid co-load (e.g., 500–1000 mL) at time of spinal; avoid fluid overload in pre-eclampsia/cardiac disease; consider colloid only per local policy/risk-benefit

Intra-operative management

Monitoring: NIBP frequent until stable, ECG, SpO2; consider invasive BP if severe disease/major haemorrhage risk; end-tidal CO2 if sedated with capnography via nasal cannula if available
Nausea/vomiting: treat hypotension first; antiemetics (ondansetron, cyclizine, metoclopramide) as needed; consider that uterine exteriorisation/traction can trigger symptoms
Uterotonics: oxytocin can cause hypotension/tachycardia; give as slow IV dose/infusion per local policy; be prepared for haemodynamic changes and treat promptly
Sedation: generally avoid or minimal (maternal awareness and airway risk); if needed, small titrated doses (e.g., midazolam after delivery, or low-dose propofol infusion) with full monitoring and readiness to manage airway
Analgesia plan: intrathecal morphine (if used) + regular paracetamol and NSAID (if not contraindicated) + rescue opioid; consider TAP block/wound infiltration if no intrathecal morphine or high pain risk

Failed/patchy spinal and conversion plan

Recognise early: inadequate level, unilateral block, sacral sparing, pain on incision/traction; stop surgery if possible and reassess
Immediate actions: confirm test modality and dermatomes; optimise position; consider time (some blocks ascend slowly); treat anxiety and hypotension
Options depending on urgency and circumstances
- Repeat spinal (with caution): only if clear failure (e.g., no block) and safe to do so; reduce dose to avoid high/total spinal; document and involve senior
- Convert to epidural/CSE top-up if catheter present (not applicable to single-shot spinal unless CSE used)
- Proceed to GA if inadequate block and delivery cannot be delayed; follow obstetric GA/failed intubation plans; consider aspiration risk

Complications and management

Hypotension
- Left uterine displacement, vasopressor bolus/infusion, fluid co-load, treat bradycardia if present; consider other causes (haemorrhage, aortocaval compression, high spinal)
High/total spinal
- Features: rapidly rising block, arm/hand tingling, dyspnoea, inability to speak, hypotension, bradycardia, nausea, LOC; may progress to apnoea
- Management: call for help; left uterine displacement; 100% O2; support ventilation (BVM) early; treat hypotension/bradycardia (phenylephrine/metaraminol, atropine; consider epinephrine in extremis); prepare RSI and intubation; reassure patient if awake; consider intralipid only if LAST suspected (rare with spinal doses)
Local anaesthetic systemic toxicity (LAST)
- Very unlikely with standard intrathecal bupivacaine doses; consider if inadvertent IV injection (more relevant to epidural) or large doses used; treat per AAGBI/RA-UK lipid rescue guidance
PDPH
- Postural headache ± neck stiffness, photophobia, tinnitus; risk reduced with pencil-point small gauge; treat with hydration, simple analgesics, caffeine (limited), and consider epidural blood patch if severe/persistent
Neurological injury / infection / haematoma
- Rare; red flags: severe back pain, progressive motor weakness, sensory changes, sphincter dysfunction, fever; urgent senior review and MRI if concern for epidural haematoma/abscess; time-critical decompression for haematoma
Intrathecal opioid side effects
- Pruritus (common), nausea, urinary retention; delayed respiratory depression risk with intrathecal morphine—ensure appropriate post-op monitoring and naloxone availability

Special situations (high-yield)

Pre-eclampsia
- Spinal is usually safe; hypotension may be less pronounced due to higher SVR, but avoid fluid overload; consider invasive BP if severe; check platelets/trend and coagulation if indicated; magnesium therapy increases risk of hypotonia/resp depression with sedatives/opioids
Obesity
- Difficult positioning/landmarks; consider ultrasound; anticipate difficult airway even for spinal case; ensure ramping and airway plan; higher risk of high block if repeat dosing; consider CSE for flexibility
Placenta praevia/accreta spectrum (PAS)
- High haemorrhage risk; consider CSE/epidural or GA depending on plan; invasive monitoring, large-bore access, blood products, cell salvage, major haemorrhage protocol; multidisciplinary planning
Category-1 CS (immediate threat to life of woman or fetus)
- Decision-to-delivery time pressure: if functioning epidural in situ, rapid top-up may be fastest; otherwise GA often; spinal may be appropriate in selected cases with experienced team and immediate readiness to convert

Talk me through how you would provide spinal anaesthesia for an elective caesarean section.

Structure: preparation → technique → confirmation → haemodynamic strategy → analgesia and post-op plan.

Preparation: confirm indication/urgency; consent (including conversion to GA); aspiration prophylaxis; IV access; baseline BP; vasopressors drawn up; left uterine displacement ready; antibiotics per policy
Technique: asepsis; sitting/lateral; L3/4 or L4/5; 25–27G pencil-point; confirm free CSF; inject hyperbaric bupivacaine + opioid; lay supine with tilt
Assess block: cold/light touch to T4 bilaterally before incision; manage anxiety; avoid excessive sedation
Haemodynamics: prophylactic phenylephrine infusion or boluses; crystalloid co-load; treat hypotension promptly; manage bradycardia
Analgesia: intrathecal morphine if appropriate; regular paracetamol + NSAID; antiemetics; post-op monitoring for respiratory depression

What level of block is required for caesarean section and how do you test it?

Examiners want: level, modality, bilateral assessment, and relevance to peritoneal traction.

Aim for sensory block to T4 (nipple line) to cover peritoneal traction and uterine manipulation
Test bilaterally using cold (ice/ethyl chloride) or light touch; pinprick may be unreliable and unpleasant; document dermatomal level
Assess progression over time; be cautious of sacral sparing/unilateral block; confirm before incision

Why does spinal anaesthesia cause hypotension in pregnancy, and why is it important?

Core physiology + fetal implications.

Sympathetic blockade → vasodilation (↓SVR) and venous pooling (↓venous return) → ↓CO
Aortocaval compression worsens venous return when supine; pregnancy reduces CSF volume and increases spread
Uteroplacental blood flow is pressure-dependent (no autoregulation): severe/prolonged maternal hypotension can cause fetal hypoxia/acidaemia; maternal symptoms include nausea/vomiting

How would you prevent and treat spinal-induced hypotension for caesarean section?

Expect: left tilt, vasopressors, fluids, targets, and bradycardia management.

Prevent: left uterine displacement; crystalloid co-load; start prophylactic phenylephrine infusion or be ready with boluses; frequent BP monitoring
Treat: vasopressor bolus/infusion titrated to maintain SBP near baseline; treat bradycardia (atropine) and consider epinephrine if cardiovascular collapse
Reassess: ensure tilt adequate; exclude high spinal or haemorrhage; communicate with obstetricians

Compare phenylephrine and ephedrine for obstetric spinal hypotension.

A common FRCA theme: maternal CO/HR effects and fetal acid-base.

Phenylephrine: pure alpha agonist → ↑SVR, may cause reflex bradycardia and reduced maternal CO; associated with better fetal acid-base compared with ephedrine in many studies
Ephedrine: mixed alpha/beta → maintains HR/CO but crosses placenta and increases fetal metabolic rate; associated with more fetal acidosis
Practical: phenylephrine often first-line; ephedrine may be useful when hypotension is accompanied by significant bradycardia (depending on local practice)

A woman becomes breathless and says she cannot move her arms after the spinal. What is happening and what will you do?

This is high/total spinal until proven otherwise.

Diagnosis: high/total spinal with cervical/thoracic spread causing hypotension, bradycardia, respiratory compromise; consider differential (anxiety, local anaesthetic toxicity, pulmonary embolus) but treat as high spinal immediately
Immediate management: call for help; left uterine displacement; 100% oxygen; support ventilation early with bag-mask; prepare for RSI and intubation
Circulation: aggressive vasopressor therapy; treat bradycardia (atropine); consider epinephrine in severe hypotension/cardiac arrest; start CPR if needed with manual uterine displacement/tilt
Communication: reassure if conscious; inform obstetric team; consider urgent delivery if maternal resuscitation compromised

Your spinal seems inadequate at skin incision. How do you manage a failed or patchy spinal for caesarean section?

Key: stop, assess, decide based on urgency, avoid high spinal from repeat dosing.

Stop surgery if possible; assess block level bilaterally with appropriate modality; check time since injection and patient position
If no block at all: consider intrathecal failure; repeat spinal may be reasonable with reduced dose and senior input; avoid repeating full dose
If partial/patchy: options limited with single-shot spinal—often proceed to GA if urgent; if non-urgent, consider waiting briefly, repositioning, or conversion strategies per local policy
Analgesia/sedation alone is not a substitute for surgical anaesthesia; avoid masking pain with heavy sedation in a full-stomach patient

What are the complications of intrathecal morphine in caesarean section and how do you monitor/manage them?

Expect pruritus, N&V, urinary retention, and delayed respiratory depression with monitoring requirements.

Common: pruritus, nausea/vomiting; treat with antiemetics, low-dose naloxone infusion if troublesome pruritus (local policy), or antihistamines (sedating)
Serious: delayed respiratory depression (hours after); ensure appropriate post-op observations (RR, sedation score, SpO2) per local guideline; have naloxone available
Other: urinary retention; counsel patient and coordinate catheter management

Outline the causes, diagnosis, and management of PDPH after obstetric spinal anaesthesia.

A frequent FRCA viva topic.

Cause: CSF leak through dural puncture → intracranial hypotension and meningeal traction; risk increased with cutting needles and larger gauge; reduced with pencil-point needles
Diagnosis: postural headache (worse upright, relieved supine) ± neck stiffness, photophobia, tinnitus; exclude other causes in postpartum (pre-eclampsia, meningitis, intracranial pathology)
Management: conservative (analgesia, hydration, caffeine with caution) and early anaesthetic review; epidural blood patch for severe or persistent symptoms after discussion of risks/benefits

Discuss spinal anaesthesia for caesarean section in a woman with severe pre-eclampsia.

Examiners want: safety, haemodynamics, fluids, coagulation, magnesium, monitoring.

Spinal is usually appropriate; hypotension may be less pronounced but still treat promptly; avoid fluid overload; consider invasive BP if severe features
Check platelets and trend; consider coagulation if HELLP suspected; follow local neuraxial thresholds and senior involvement
Magnesium therapy: potentiates neuromuscular weakness and respiratory depression with sedatives/opioids; be cautious with additional CNS depressants