Labour Analgesia

Quick Answer

Labour analgesia is provided for approximately 80% of births in Australian tertiary centres, with epidural analgesia being the gold standard for pain relief in labour. The neuraxial techniques (epidural, combined spinal-epidural [CSE]) provide superior analgesia compared to systemic opioids or non-pharmacological methods, with patient satisfaction scores of 85-95%. Epidural analgesia involves placement of a catheter in the lumbar epidural space (typically L3-L4 or L4-L5) with administration of low-dose local anaesthetic (bupivacaine 0.0625-0.125%) combined with lipid-soluble opioid (fentanyl 2-5 μg/mL or sufentanil 0.5-1 μg/mL) to achieve T10-L1 sensory blockade. CSE technique offers rapid onset (2-5 minutes) with intrathecal opioid (fentanyl 25 μg or sufentanil 5-10 μg) followed by epidural catheter placement for continuous infusion. Contraindications include coagulopathy (platelets <80 × 10⁹/L, INR >1.4), infection at insertion site, patient refusal, severe hypovolaemia, and increased intracranial pressure. Complications include hypotension (15-30% incidence, managed with fluids, left uterine displacement, phenylephrine/ephedrine), inadequate block (10-15%, managed with catheter manipulation or re-siting), post-dural puncture headache (1-2% with inadvertent dural puncture), and neurological injury (rare, <0.1%). Indigenous maternity care requires culturally safe communication, involvement of Aboriginal midwives/liaison officers, and consideration that Aboriginal women have higher rates of gestational diabetes and pre-eclampsia, requiring careful haemodynamic monitoring and analgesic management tailored to individual needs and cultural preferences. [1-10]

Pathophysiology

Pain Mechanisms in Labour

First Stage Labour Pain:

Cervical Dilation and Uterine Contractions (0-10 cm):

• Origin: Uterine contractions, cervical dilation, lower uterine segment distension
• Pathway: Visceral afferents via hypogastric plexus → sympathetic chain → enter spinal cord at T10-L1 levels
• Characteristics: Dull, cramping, poorly localized, referred to lower back and thighs
• Intensity: Increases progressively with cervical dilation (mild at 1-2 cm, severe at 8-10 cm)

Neurophysiology:

• Aδ and C fibers: Transmit nociceptive signals from uterus and cervix
• Prostaglandin release: Increases with cervical ripening, sensitizes nociceptors
• Oxytocin surge: Intensifies uterine contractions and pain
• Referred pain patterns: T10-L1 dermatomes (lower abdomen, back, upper thighs)

Second Stage Labour Pain:

Perineal Distension and Fetal Descent:

• Origin: Perineal stretching, vaginal distension, pelvic floor pressure
• Pathway: Somatic afferents via pudendal nerve (S2-S4) and genitofemoral nerve (L1-L2)
• Characteristics: Sharp, burning, intense, well-localized
• Intensity: Severe, often described as "tearing" or "splitting"

Neurophysiology:

• Pudendal nerve: Primary innervation of perineum, posterior vaginal wall
• Genitofemoral nerve: Anterior vaginal wall, labia
• Levator ani muscles: Stretch and pressure contribute to pain
• Perineal tear risk: Pain intensity correlates with risk of severe perineal injury (3rd/4th degree tears)

Third Stage Pain:

• Placental separation: Uterine contraction and placental detachment
• Lower intensity: Less severe than first and second stage
• Managed with: Oxytocin administration, fundal massage

Neuraxial Analgesia Mechanisms

Epidural Analgesia:

Local Anaesthetic Action:

• Sodium channel blockade: Inhibits action potential propagation in Aδ and C fibers
• Differential blockade: Smaller fibers (pain) blocked before larger fibers (motor)
• Segmental distribution: Spreads according to dermatomal levels (T10-L1 for first stage, S2-S4 for second stage)

Opioid Mechanism (Epidural):

• μ-opioid receptors: Located in dorsal horn of spinal cord
• Lipid-soluble opioids: Fentanyl, sufentanil (rapid onset, limited systemic absorption)
• Synergistic effect: Local anaesthetic + opioid reduces dose requirements and side effects
• Dose-sparing: Allows 30-50% reduction in local anaesthetic concentration

Combined Spinal-Epidural (CSE):

Intrathecal Opioid Action:

• Direct CSF action: Opioid in cerebrospinal fluid binds to spinal cord receptors
• Rapid onset: 2-5 minutes (vs. 10-20 minutes for epidural alone)
• Profound analgesia: Intrathecal fentanyl 25 μg or sufentanil 5-10 μg
• Limited motor block: Preserves ambulation ("walking epidural")
• Sequential analgesia: Intrathecal for immediate relief, epidural for maintenance

Systemic Opioid Pharmacology

Meperidine (Pethidine):

• Dose: 50-100 mg IM/IV q3-4h
• Onset: 10-20 minutes IV, 30-60 minutes IM
• Duration: 2-4 hours
• Metabolism: Hepatic (CYP2B6) to active metabolite normeperidine
• Neonatal effects: Respiratory depression, decreased alertness, impaired sucking (normeperidine crosses placenta, long half-life in neonate)
• Side effects: Maternal nausea, vomiting, dysphoria, neonatal depression
• Use: Declining due to neonatal effects; only if neuraxial contraindicated

Fentanyl:

• Dose: 50-100 μg IV q1-2h or PCA 10-20 μg bolus q5-10min
• Onset: 1-2 minutes IV
• Duration: 30-60 minutes
• Metabolism: Hepatic (CYP3A4)
• Neonatal effects: Less than meperidine; transient respiratory depression
• Side effects: Maternal sedation, nausea, pruritus
• Use: Short-acting option for labour, less neonatal depression than meperidine

Remifentanil:

• Dose: 0.2-0.4 μg/kg/min IV infusion + 0.5-1 μg/kg bolus q2-3min
• Onset: 1 minute
• Duration: 5-10 minutes (context-sensitive half-life)
• Metabolism: Plasma esterases (rapid, organ-independent)
• Neonatal effects: Minimal; rapidly cleared by fetus
• Side effects: Maternal sedation, respiratory depression, nausea
• Use: When neuraxial contraindicated; requires 1:1 midwifery observation; best alternative to epidural in high-risk patients

Clinical Presentation

Labour Pain Assessment

Assessment Domains:

1. Pain Characteristics:

• Location: Uterine/cervical vs. perineal
• Quality: Cramping vs. sharp/burning
• Intensity: Mild, moderate, severe, or unbearable
• Temporal: Continuous vs. contraction-related
• Pattern: Regular vs. irregular contractions

2. Functional Impact:

• Mobility: Ability to ambulate, position changes
• Coping: Breathing techniques, relaxation
• Emotional state: Anxiety, fear, distress
• Fatigue: Duration of labour, sleep deprivation

3. Obstetric Factors:

• Cervical dilation and effacement
• Fetal position and station
• Labour progress: Active labour vs. latent phase
• Risk factors: Pre-eclampsia, fetal distress, bleeding

4. Contraindications Assessment:

• Coagulation status: Platelet count, INR
• Infection: Fever, chorioamnionitis
• Anatomy: Prior spinal surgery, scoliosis
• Patient factors: Refusal, anxiety, co-morbidities

Validated Pain Assessment Tools

Visual Analog Scale (VAS) or Numeric Rating Scale (NRS):

• Scale: 0-10 or 0-100
• Timing: At rest and during contractions
• Use: Baseline assessment, monitoring response to analgesia
• Target: ≤3/10 for adequate analgesia

Verbal Descriptor Scale:

• Categories: None, Mild, Moderate, Severe, Unbearable
• Use: Quick assessment, cognitive impairment

Maternal Satisfaction Scores:

• Post-delivery assessment of analgesia effectiveness
• Satisfaction with pain management
• Would choose same analgesia again?

Management

Neuraxial Analgesia Techniques

Epidural Analgesia:

Indications:

• Maternal request for pain relief
• Prolonged or difficult labour
• Instrumental delivery or caesarean section anticipated
• Multiple pregnancy
• Pre-eclampsia or other high-risk conditions
• Patient refusal of systemic opioids

Contraindications:

• Absolute:
  • Patient refusal
  • Coagulopathy (platelets <80 × 10⁹/L, INR >1.4, APTT >45s)
  • Infection at insertion site (cellulitis, abscess)
  • Severe hypovolaemia/shock
  • Increased intracranial pressure
  • Severe spinal deformity preventing safe insertion
• Relative:
  • Thrombocytopenia 80-100 × 10⁹/L (individual risk assessment)
  • Previous spinal surgery (more difficult insertion, higher risk)
  • Systemic infection (fever, chorioamnionitis)
  • Anticoagulation therapy (timing dependent on drug)

Technique:

Preparation:

1. Informed consent: Explain procedure, benefits, risks, alternatives
2. IV access: Patent 16-18G IV cannula
3. Monitoring: Continuous ECG, SpO₂, intermittent BP (q5min initially)
4. Left uterine displacement: 15° left lateral tilt to prevent aortocaval compression
5. Positioning: Sitting or lateral decubitus
6. Skin preparation: Chlorhexidine or iodine solution
7. Sterile technique: Full aseptic technique, sterile gown, gloves, drape

Insertion:

1. Identify interspace: Tuffier's line (L4-L5) or L3-L4
2. Local anaesthetic: 1% lignocaine subcutaneous and intradermal
3. Epidural needle: 16-18G Tuohy needle
4. Loss of resistance: Saline or air technique to identify epidural space
5. Catheter insertion: 4-6 cm into epidural space
6. Aspiration: Check for blood or CSF (should be negative)
7. Test dose: 3 mL lidocaine 1% + adrenaline (1:200,000) to exclude intrathecal or IV placement
8. Secure catheter: Dressing, filter, catheter stabilization device

Dosing:

Loading Dose:

• Local anaesthetic: Bupivacaine 0.0625-0.125% 10-15 mL
• Opioid: Fentanyl 50-100 μg OR sufentanil 10-20 μg
• Onset: 10-20 minutes
• Sensory block: Target T10-L1 for first stage, extend to S2-S4 for second stage

Maintenance:

Continuous Infusion:

• Solution: Bupivacaine 0.0625-0.1% + fentanyl 2-5 μg/mL
• Rate: 8-12 mL/hour (titrate to analgesia)
• Advantages: Steady analgesia, less motor block, reduced workload

Patient-Controlled Epidural Analgesia (PCEA):

• Background infusion: 4-8 mL/hour
• Bolus: 3-5 mL
• Lockout: 10-20 minutes
• Hourly limit: 15-20 mL
• Advantages: Patient autonomy, improved satisfaction, reduced anaesthetist workload

Intermittent Top-ups:

• Volume: 10-15 mL of solution
• Frequency: q60-90 minutes PRN
• Disadvantages: Breakthrough pain, peaks and troughs, requires anaesthetist presence

Combined Spinal-Epidural (CSE):

Indications:

• Rapid analgesia needed (advanced labour, distress)
• Ambulatory analgesia desired
• Patient request for rapid onset

Technique:

1. Spinal component:
   • 25-27G pencil-point spinal needle through epidural needle (needle-through-needle)
   • Intrathecal dose: Fentanyl 25 μg OR sufentanil 5-10 μg
   • ± Bupivacaine 2.5 mg (if motor block acceptable)
2. Epidural component:
   • Insert epidural catheter immediately after spinal
   • Start infusion once spinal wearing off (usually 1-2 hours)

Advantages:

• Rapid onset (2-5 minutes)
• Profound analgesia (intrathecal opioid)
• Preserved motor function (walking possible)
• Continuous analgesia via epidural catheter

Disadvantages:

• Technique more complex
• Risk of post-dural puncture headache (if dural puncture occurs)
• Fetal bradycardia risk (uterine hypertonus from rapid analgesia)

Complications and Management

Hypotension:

Incidence: 15-30% with neuraxial analgesia

Mechanism:

• Sympathetic blockade → vasodilation → venous pooling → decreased venous return → reduced cardiac output
• Aortocaval compression exacerbates hypotension in supine position

Prevention:

• Left uterine displacement (15° left lateral tilt)
• Preload with crystalloid 500-1000 mL (limited efficacy, may cause fluid overload)
• Avoid supine position

Management:

1. Left uterine displacement: Increase tilt to 30° left lateral
2. Fluid bolus: 500-1000 mL crystalloid
3. Vasopressors:
   • Phenylephrine: 50-100 μg IV bolus (first-line, pure α-agonist)
   • Ephedrine: 5-10 mg IV bolus (α and β agonist, may cause fetal tachycardia)
4. Oxygen: 100% oxygen via face mask if maternal hypoxia
5. Monitor fetus: Continuous CTG if hypotension severe or prolonged

Inadequate Block:

Incidence: 10-15% of epidurals

Causes:

• Catheter malposition: Epidural vein, subdural space, insufficient depth
• One-sided block: Catheter lateralized to one side
• Patchy block: Septations in epidural space prevent spread
• Tolerant patient: Prior opioid use, chronic pain
• Rapid labour: Cervical dilation >8 cm with inadequate time for block establishment

Management:

1. Assess catheter: Check position, depth, kinks
2. Reposition patient: Supine or lateral to encourage spread
3. Additional dose: 5-10 mL local anaesthetic (check for intrathecal/IV placement)
4. Catheter manipulation: Withdraw 1-2 cm if one-sided
5. Replace catheter: If still inadequate after troubleshooting

Post-Dural Puncture Headache (PDPH):

Incidence: 1-2% (higher with larger needles, multiple attempts)

Mechanism:

• Inadvertent dural puncture → CSF leak → decreased CSF volume → intracranial hypotension → traction on pain-sensitive structures

Characteristics:

• Onset: 24-72 hours post-procedure
• Position-dependent: Worse upright, better supine
• Quality: Frontal or occipital, throbbing
• Associated symptoms: Nausea, vomiting, photophobia, tinnitus, diplopia

Management:

1. Conservative:
   • Bed rest (though may prolong headache)
   • Hydration (IV or oral)
   • Caffeine (500 mg PO or IV)
   • Analgesics (paracetamol, NSAIDs, caffeine-containing medications)
2. Epidural blood patch (EBP):
   • Indications: Severe headache, failed conservative management, patient preference
   • Technique: 15-20 mL autologous blood injected into epidural space at level of original puncture or L3-L4
   • Mechanism: Blood patches dural hole, restores CSF pressure
   • Success rate: 70-90% (may need repeat if initial fails)
   • Timing: Usually performed after 24-48 hours of failed conservative treatment

Fetal Bradycardia:

Incidence: 5-15% following neuraxial analgesia (especially CSE)

Mechanism:

• Rapid analgesia → decreased circulating catecholamines → uterine hypertonus/tetany → reduced uteroplacental perfusion → fetal hypoxia → bradycardia
• More common with intrathecal opioids (rapid onset)

Management:

1. Left uterine displacement: Reduce aortocaval compression
2. Oxygen: 100% oxygen via face mask
3. Intravenous fluids: 500-1000 mL crystalloid
4. Tocolysis:
   • Terbutaline: 250 μg SC (relaxes uterus)
   • Nitroglycerin: 50-100 μg IV (rapid onset, short duration)
5. Monitor CTG: Continuous fetal monitoring until recovery
6. Prepare for operative delivery: If bradycardia persists (>3-5 minutes) or fetal compromise evident

Usually self-limiting: Resolves within 5-10 minutes with above measures

Neurological Injury:

Incidence: <0.1% (rare but serious)

Causes:

• Direct trauma: Needle or catheter damage to nerve roots, spinal cord
• Haematoma: Epidural haematoma compressing spinal cord or cauda equina
• Infection: Epidural abscess, meningitis
• Chemical injury: Accidental injection of wrong drug (e.g., thiopental, potassium chloride)

Presentation:

• New neurological deficit following neuraxial block
• Weakness, sensory loss, bowel/bladder dysfunction
• Back pain, fever (if infectious)

Management:

1. Immediate assessment: Neurological examination, document deficits
2. Imaging: MRI spine (gold standard for identifying haematoma, abscess, structural injury)
3. Surgical consultation: Neurosurgical or orthopaedic spinal intervention
4. Evacuation: Emergency decompression if epidural haematoma confirmed
5. Antibiotics: Broad-spectrum if infection suspected
6. Rehabilitation: Physiotherapy for residual deficits

Urgent evaluation: Any new neurological deficit following neuraxial block requires urgent MRI and neurosurgical consultation

Alternative Analgesia Methods

Systemic Opioids:

Meperidine (Pethidine):

• Dose: 50-100 mg IM q3-4h or 25-50 mg IV q2-3h
• Onset: 10-20 min IV, 30-60 min IM
• Duration: 2-4 hours
• Neonatal effects: Respiratory depression, decreased alertness (normeperidine crosses placenta)
• Use: Limited due to neonatal effects; only if neuraxial contraindicated

Fentanyl:

• Dose: 50-100 μg IV q1-2h or PCA 10-20 μg bolus q5-10min
• Onset: 1-2 minutes
• Duration: 30-60 minutes
• Neonatal effects: Transient respiratory depression
• Use: Short labour, rapid onset/offset

Remifentanil:

• Dose: 0.2-0.4 μg/kg/min infusion + 0.5-1 μg/kg bolus q2-3min (PCA mode)
• Onset: 1 minute
• Duration: 5-10 minutes
• Metabolism: Plasma esterases (organ-independent, rapid fetal clearance)
• Neonatal effects: Minimal
• Monitoring: Continuous pulse oximetry, 1:1 midwifery observation
• Use: Best alternative to neuraxial when contraindicated; requires high-level monitoring

Nitrous Oxide (Entonox):

• Concentration: 50% N₂O + 50% O₂
• Administration: Self-administered via face mask or mouthpiece
• Onset: 30-60 seconds
• Duration: Rapid offset after stopping inhalation
• Mechanism: NMDA receptor antagonism, opioid receptor activation
• Efficacy: Moderate (30-40% pain reduction)
• Side effects: Nausea, dizziness, dysphoria, environmental pollution
• Use: Early labour, patients declining neuraxial, intermittent analgesia

Non-Pharmacological Methods:

Water Immersion:

• Warm water bath (37-38°C)
• Mechanism: Buoyancy reduces pressure, warmth relaxes muscles, distraction
• Efficacy: Reduces pain intensity, shortens labour, reduces need for pharmacological analgesia
• Contraindications: Prolonged rupture of membranes, meconium staining, fetal compromise
• Use: First stage labour, birth centre or low-risk settings

TENS (Transcutaneous Electrical Nerve Stimulation):

• Application: Electrodes on back (T10-L1 dermatomes) or acupuncture points
• Mechanism: Gate control theory (blocks pain transmission)
• Efficacy: Modest (10-20% pain reduction)
• Use: Early labour, back pain predominant, adjunct to other methods

Acupuncture/Acupressure:

• Points: LI4, SP6, BL32, GB21
• Mechanism: Endogenous opioid release, modulation of pain pathways
• Efficacy: Variable, some evidence for pain reduction
• Use: Complementary therapy, patient preference

Hypnosis/Relaxation:

• Techniques: Breathing exercises, visualization, progressive muscle relaxation
• Mechanism: Reduced anxiety, distraction, modulation of pain perception
• Efficacy: Individual variability
• Use: Preparation for labour, adjunct to pharmacological methods

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Maternity Care:

Cultural Safety in Labour Analgesia:

Communication and Understanding:

• Medical terminology and analgesic concepts require culturally safe explanation
• Use of Aboriginal midwives or Aboriginal Hospital Liaison Officers essential
• Involvement of family members in decision-making processes
• Respect for traditional birthing practices alongside medical care

Higher Risk Profile:

Aboriginal and Torres Strait Islander women have higher rates of conditions affecting labour analgesia:

• Gestational diabetes: 10-15% (vs. 5-8% non-Indigenous)
  • Higher risk of pre-eclampsia, macrosomia
  • May require insulin therapy, closer fetal monitoring
• Pre-eclampsia: 2-3 times higher incidence
  • Requires careful haemodynamic monitoring with neuraxial analgesia
• Obesity: Higher prevalence
  • Technical challenges with neuraxial placement (difficult landmarks)
  • Higher risk of hypotension, failed block
  • May require ultrasound guidance for epidural
• Anaemia: Higher prevalence (nutritional deficiencies, chronic disease)
  • Higher risk of hypotension with neuraxial block
  • Lower physiological reserve

Analgesia Considerations:

Epidural Considerations:

• Difficult insertion: Obesity and anatomical variations may make epidural technically challenging
• Ultrasound use: Consider ultrasound guidance for epidural placement in difficult cases
• CSE technique: May be preferred for rapid analgesia if technically difficult insertion anticipated
• Hypotension risk: Higher baseline cardiovascular risk may increase hypotension severity

Pain Assessment:

• Cultural expression: Pain may be expressed differently (stoicism vs. vocalization)
• Communication barriers: Language differences, health literacy
• Assessment tools: Use visual aids, simple language
• Validate pain experience: Ensure pain is acknowledged and not minimized

Support Systems:

• Family presence: Important cultural practice during labour
• Birthing on Country: Where possible, support traditional birthing practices
• Aboriginal Health Workers: Involvement in care planning and communication
• Cultural protocols: Respect for women's business and men's business

Access Issues:

• Remote communities: Limited access to epidural services
• Transfer delays: May need early transfer for high-risk pregnancies
• Choice limitations: May not have full range of analgesic options available
• Follow-up care: Postpartum pain management may be limited in remote settings

Documentation:

• Clear documentation of analgesia plan
• Communication with remote health services for follow-up
• Cultural considerations documented

Māori Health Considerations (New Zealand)

Cultural Safety in Labour Analgesia:

Whānau Involvement:

• Extended family involvement in labour and birth decisions
• Collective decision-making regarding analgesia choices
• Respect for whānau input on pain management approaches

Tikanga (Cultural Protocols):

• Tapu of birth: Sacred nature of childbirth
• Whenua (placenta): Cultural significance and traditional practices
• Karakia: May be requested before procedures
• Gender considerations: Some procedures may have cultural restrictions

Health Literacy:

• Plain language explanations of analgesic options
• Visual aids and demonstration
• Time for questions and understanding
• Use of Māori Health Workers for cultural safety

Access Issues:

• Geographic isolation may limit epidural access
• Telehealth consultation for analgesia planning
• Early transfer for high-risk pregnancies
• Coordination with primary care for postpartum pain management

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ANZCA Final Exam Focus

SAQ Patterns

Labour analgesia appears regularly in ANZCA Final Written Examination. Common SAQ themes include:

Technique-Focused Questions:

• "Describe the technique for performing an epidural for labour analgesia." (2020)
• "What are the contraindications to neuraxial analgesia in labour?" (2021)
• "Compare epidural versus combined spinal-epidural for labour analgesia."

Complication-Focused Questions:

• "How would you manage hypotension following epidural insertion in a labouring patient?"
• "Describe the management of post-dural puncture headache."
• "What are the causes and management of inadequate epidural block?"

Pharmacology Questions:

• "Explain the pharmacology of local anaesthetics used for labour epidural analgesia."
• "Compare meperidine, fentanyl, and remifentanil for labour analgesia."
• "What is the mechanism of action of epidural opioids?"

Indigenous Health Questions:

• "What specific considerations apply to labour analgesia for Aboriginal women?"
• "How would you manage cultural safety in labour analgesia for Indigenous patients?"

Marking Scheme Priorities:

• Technique description (needle, catheter, test dose)
• Contraindications (absolute vs. relative)
• Complication management (hypotension, PDPH, fetal bradycardia)
• Drug dosing and pharmacology
• Indigenous health considerations
• Red flag recognition

Clinical Viva Themes

The Clinical Viva frequently includes labour analgesia scenarios:

Scenario Types:

• Epidural insertion technique and troubleshooting
• Management of hypotension in labour
• PDPH diagnosis and management
• Contraindications assessment
• Alternative analgesia when neuraxial contraindicated
• High-risk obstetric patient analgesia (pre-eclampsia, cardiac disease)

Examiner Expectations:

• Systematic technique description
• Knowledge of contraindications
• Understanding of complication management
• Dosing and pharmacology knowledge
• Indigenous health considerations
• Patient communication and consent

Common Viva Questions:

• "Describe how you would insert an epidural for labour."
• "What are the contraindications to epidural analgesia?"
• "How would you manage hypotension after epidural insertion?"
• "What are the causes of inadequate epidural block?"
• "How does remifentanil compare to epidural analgesia?"
• "What are the signs of post-dural puncture headache?"
• "How would you manage fetal bradycardia after CSE?"

Key Points for Examination Success

1. Epidural technique is foundational — know needle, catheter, test dose
2. Contraindications — absolute vs. relative, coagulation thresholds
3. Complication management — hypotension (fluids, vasopressors, position), PDPH (EBP), fetal bradycardia (tocolysis)
4. Dosing — local anaesthetic concentrations, opioid doses
5. Alternative analgesia — remifentanil as best non-neuraxial option
6. Indigenous health — cultural safety, higher risk profile, access issues
7. Pharmacology — understand mechanism of neuraxial opioids
8. Safety — informed consent, monitoring, documentation

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Assessment Content

SAQ Practice Question 1 (20 marks)

Question:

A 28-year-old primigravida (70 kg) at 38 weeks gestation is admitted in active labour with cervical dilation 6 cm. She requests epidural analgesia. Her platelet count is 95 × 10⁹/L. Her blood pressure is 110/70 mmHg.

(a) What are the contraindications to neuraxial analgesia and does this patient have any? (6 marks)

(b) Describe your technique for performing an epidural for labour analgesia. (8 marks)

(c) Thirty minutes after epidural insertion, the patient's blood pressure drops to 85/50 mmHg. Describe your management. (6 marks)

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Model Answer:

(a) Contraindications to Neuraxial Analgesia (6 marks)

Absolute Contraindications [3 marks]

1. Patient refusal [0.5 marks]

   • Patient must provide informed consent
   • Cannot proceed against patient's wishes

2. Coagulopathy [1 mark]

   • Platelets <80 × 10⁹/L: Risk of epidural haematoma
   • INR >1.4: Risk of bleeding
   • APTT >45 seconds: Risk of bleeding
   • This patient has platelets 95 × 10⁹/L — relative contraindication only

3. Infection at insertion site [0.5 marks]

   • Cellulitis, abscess, open wounds
   • Risk of introducing infection into epidural space

4. Severe hypovolaemia/shock [0.5 marks]

   • Sympathetic blockade worsens hypotension
   • May precipitate cardiovascular collapse

5. Increased intracranial pressure [0.5 marks]

   • Risk of brain herniation with CSF leak
   • Contraindication to dural puncture

Relative Contraindications [2 marks]

1. Thrombocytopenia 80-100 × 10⁹/L [0.5 marks]

   • This patient's platelets 95 × 10⁹/L falls in this range
   • Individual risk assessment required
   • Consider bleeding history, trend of platelet count
   • Discuss risks/benefits with patient
   • May proceed with caution if benefits outweigh risks

2. Previous spinal surgery [0.5 marks]

   • More difficult insertion
   • Higher risk of complications
   • Not absolute if technically feasible

3. Systemic infection [0.5 marks]

   • Fever, chorioamnionitis
   • Risk of epidural abscess
   • Weigh benefits vs. risks

4. Anticoagulation therapy [0.5 marks]

   • Timing-dependent (heparin, warfarin, LMWH)
   • Consult guidelines for specific drug timing

This Patient:

• Platelet count 95 × 10⁹/L: Relative contraindication (not absolute)
• No absolute contraindications present
• May proceed with neuraxial analgesia after informed consent regarding bleeding risk
• Individualized decision: Balance benefits of effective analgesia vs. small risk of epidural haematoma

(b) Epidural Technique (8 marks)

Preparation [2 marks]

1. Informed consent [0.5 marks]

   • Explain procedure, benefits (effective analgesia), risks (hypotension, headache, inadequate block)
   • Discuss alternatives (systemic opioids, nitrous oxide)
   • Document consent

2. IV access and monitoring [0.5 marks]

   • 16-18G IV cannula
   • Continuous ECG, SpO₂
   • BP cuff for intermittent monitoring (q5min initially)
   • Fetal monitoring (CTG)

3. Positioning [0.5 marks]

   • Left uterine displacement (15° left lateral tilt) — prevents aortocaval compression
   • Sitting position preferred (easier landmark identification)
   • OR lateral decubitus if patient prefers

4. Aseptic technique [0.5 marks]

   • Chlorhexidine skin preparation
   • Sterile gown, gloves, full sterile drape
   • Sterile equipment

Insertion Technique [4 marks]

1. Identify interspace [0.5 marks]

   • Tuffier's line (intercristal line) — connects highest points of iliac crests
   • Corresponds to L4 spinous process or L4-L5 interspace
   • Choose L3-L4 or L4-L5 interspace

2. Local anaesthetic infiltration [0.5 marks]

   • 1% lignocaine subcutaneous and intradermal at intended insertion site
   • 23-25G needle
   • Creates skin wheal and deeper infiltration

3. Epidural needle insertion [0.5 marks]

   • 16-18G Tuohy needle
   • Insert through skin wheal, directed cephalad 10-15°
   • Advance through supraspinous ligament, interspinous ligament

4. Loss of resistance technique [0.5 marks]

   • Attach syringe (saline or air) to needle
   • Advance needle slowly with intermittent pressure on syringe
   • Sudden loss of resistance = entry into epidural space
   • Saline preferred (air risk of air embolism, less reliable)

5. Catheter insertion [0.5 marks]

   • Insert epidural catheter (19-20G) through needle 4-6 cm into epidural space
   • Remove needle while holding catheter
   • Aspirate catheter — should be negative for blood or CSF

6. Test dose [0.5 marks]

   • 3 mL lidocaine 1% + adrenaline (1:200,000)
   • Purpose: Exclude intrathecal or intravenous placement
   • Intrathecal signs: Rapid onset of spinal block (2-3 minutes), bilateral motor block
   • IV signs: Tachycardia (adrenaline), metallic taste (lidocaine), circumoral numbness

7. Secure catheter [0.5 marks]

   • Dressing over insertion site
   • Bacterial filter attached
   • Catheter stabilization device
   • Mark catheter depth at skin

Dosing [2 marks]

1. Loading dose [1 mark]

   • Bupivacaine 0.0625-0.125% 10-15 mL
   • Plus fentanyl 50-100 μg OR sufentanil 10-20 μg
   • Administer in divided doses (5 mL increments) to assess block height
   • Target sensory block: T10-L1 for first stage labour

2. Maintenance [1 mark]

   • Continuous infusion: Bupivacaine 0.0625-0.1% + fentanyl 2-5 μg/mL at 8-12 mL/hour
   • OR PCEA: Background 4-8 mL/hour, bolus 3-5 mL, lockout 10-20 min
   • Top-up as needed for breakthrough pain or second stage (perineal block)

(c) Management of Hypotension (6 marks)

Immediate Actions [2 marks]

1. Call for help [0.5 marks]

   • Alert midwife/nursing staff
   • Additional assistance if needed

2. Left uterine displacement [0.5 marks]

   • Increase left lateral tilt to 30°
   • Manual displacement of uterus if needed
   • Prevents aortocaval compression

3. Oxygen [0.5 marks]

   • 100% oxygen via face mask (15 L/min)
   • Ensure maternal oxygenation

4. Increase IV fluid rate [0.5 marks]

   • Rapid crystalloid infusion 500-1000 mL
   • Hartmann's or 0.9% saline

Pharmacological Management [2 marks]

5. Vasopressors [1.5 marks]

   • Phenylephrine (first-line): 50-100 μg IV bolus
     • Pure α-agonist (vasoconstriction)
     • Minimal fetal effects (no β-agonist activity)
   • Ephedrine: 5-10 mg IV bolus
     • α and β agonist
     • May cause fetal tachycardia (β effect)
     • Alternative if phenylephrine unavailable
   • Repeat as needed until BP restored

6. Monitor fetus [0.5 marks]

   • Continuous CTG monitoring
   • Assess for fetal bradycardia or late decelerations
   • Document fetal response to maternal resuscitation

Assessment and Prevention [2 marks]

7. Assess block height [0.5 marks]

   • Check sensory level (should be T10-L1, not higher)
   • High block (T4-T6) increases hypotension risk
   • If block too high, reduce infusion rate

8. Prevent recurrence [0.5 marks]

   • Maintain left lateral position
   • Continue BP monitoring (q5min until stable)
   • Prophylactic vasopressor protocol if recurrent

9. Document [0.5 marks]

   • BP response to interventions
   • Vasopressor doses and timing
   • Fetal status
   • Block height

10. Consider catheter adjustment [0.5 marks]

    • If recurrent hypotension, may be one-sided block or excessive height
    • Withdraw catheter 1-2 cm or reduce infusion rate

Total: 20 marks

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Viva Scenario (25 marks)

Opening Stem:

You are the consultant anaesthetist covering the labour ward. A 32-year-old primigravida (85 kg, BMI 32) at 40 weeks gestation is in active labour with cervical dilation 8 cm. She has gestational diabetes controlled with insulin. Her platelet count is 110 × 10⁹/L. She is requesting epidural analgesia and is distressed by pain (NRS 9/10). Her blood pressure is 125/78 mmHg.

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Expected Viva Progression:

Examiner: What are your concerns about performing an epidural in this patient?

Candidate Response: [4 marks]

"This patient has several factors that increase technical difficulty and risk for epidural analgesia:

1. Obesity (BMI 32) [1.5 marks]

Technical Challenges:

• Difficult landmarks: Increased subcutaneous tissue obscures bony landmarks
• Greater depth to epidural space: Standard needle (8 cm) may be insufficient
• Higher risk of accidental dural puncture: Difficult to appreciate loss of resistance
• Increased risk of hypotension: Higher baseline cardiovascular risk, greater vasodilation with block
• More difficult positioning: May need assistance maintaining position
• Higher risk of infection: Difficult to maintain sterile field, increased skin flora

Considerations:

• Ultrasound guidance: Consider using ultrasound to identify midline and depth
• Longer needle: May need 10 cm or 12 cm Tuohy needle
• Experienced operator: Ensure most skilled anaesthetist performs procedure
• Time: Allow extra time for insertion
• CSE consideration: May be technically easier than epidural alone (intrathecal opioid for rapid analgesia)

2. Platelet Count 110 × 10⁹/L [1 mark]

Risk Assessment:

• Thrombocytopenia: Mild (100-150 × 10⁹/L range)
• Epidural haematoma risk: Slightly increased, but absolute risk remains low
• Not an absolute contraindication: Proceed with caution

Considerations:

• Informed consent: Discuss small risk of epidural haematoma
• Bleeding history: Ask about easy bruising, bleeding gums, menorrhagia
• Trend: Is platelet count stable, improving, or declining?
• Proceed: Benefits of effective analgesia likely outweigh small bleeding risk

3. Gestational Diabetes [1 mark]

Management Considerations:

• Higher risk of macrosomia: May prolong second stage, increase need for instrumental delivery
• Earlier epidural: Patient at 8 cm — advanced labour, limited time for block establishment
• Haemodynamic stability: Diabetes increases risk of cardiovascular complications
• Fetal monitoring: Ensure continuous CTG (diabetes = higher fetal risk)
• Perioperative management: If caesarean section required, diabetic management critical

4. Advanced Labour (8 cm) [0.5 marks]

Timing Considerations:

• Rapid labour progression: May deliver before epidural effective
• Limited time for troubleshooting: Must achieve effective block quickly
• CSE preferred: Rapid onset with intrathecal opioid
• Patient distress: High pain scores (9/10) — rapid analgesia needed

Overall Assessment:

• Not contraindicated: Proceed with neuraxial analgesia
• Risk stratification: Higher technical difficulty, slightly increased bleeding risk
• CSE technique: Preferred for rapid onset in advanced labour
• Experienced operator: Ensure skilled anaesthetist
• Informed consent: Discuss risks specific to her situation"

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Examiner: Describe how you would perform the epidural in this patient.

Candidate Response: [5 marks]**

"Given the technical challenges (obesity, advanced labour), I would use CSE technique for rapid onset:

Preparation [1.5 marks]

1. Informed consent [0.5 marks]

   • Explain CSE technique (rapid onset, intrathecal opioid)
   • Discuss risks: hypotension, headache, inadequate block, bleeding risk with low platelets
   • Document consent

2. IV access and monitoring [0.5 marks]

   • Large-bore IV (16G) for fluid resuscitation if needed
   • Continuous ECG, SpO₂
   • BP cuff for q5min monitoring
   • Continuous CTG (gestational diabetes, advanced labour)

3. Positioning [0.5 marks]

   • Sitting position preferred (easier in obesity, better landmark identification)
   • Left uterine displacement (15° tilt) — prevents aortocaval compression
   • Assistant to help maintain position and provide support
   • Ensure patient comfortable and stable

Technique - CSE [3 marks]

4. Ultrasound assessment [0.5 marks]

   • Use curvilinear probe (2-5 MHz) to identify:
     • Midline (spinous processes)
     • Depth to ligamentum flavum/epidural space
     • Optimal insertion point
   • Mark skin with sterile marker

5. Sterile preparation [0.5 marks]

   • Chlorhexidine scrub (allow to dry)
   • Sterile full drape
   • Sterile gown and gloves

6. Local anaesthesia [0.5 marks]

   • 1% lignocaine subcutaneous and intradermal at marked site
   • 23-25G needle
   • Generous infiltration (obesity = deeper structures)

7. Epidural needle insertion [0.5 marks]

   • 16-18G Tuohy needle (consider longer 10 cm needle if ultrasound suggests deep space)
   • Midline or paramedian approach (paramedian may be easier in obesity)
   • Advance slowly with loss of resistance (saline preferred)

8. Spinal component (needle-through-needle) [0.5 marks]

   • Insert 25-27G pencil-point spinal needle through Tuohy
   • Confirm CSF return (clear fluid)
   • Inject: Fentanyl 25 μg (rapid onset, effective for labour) OR sufentanil 10 μg
   • Remove spinal needle

9. Epidural catheter [0.5 marks]

   • Insert 19-20G catheter 4-6 cm into epidural space
   • Aspirate (negative for blood/CSF)
   • Test dose: 3 mL lidocaine 1% + adrenaline

10. Secure and load [0.5 marks]

    • Dressing, filter, catheter stabilization
    • Loading dose: Bupivacaine 0.0625% 5-10 mL (gradual dosing)
    • Start infusion: Bupivacaine 0.0625% + fentanyl 2 μg/mL at 10 mL/hour
    • Or PCEA setup if available

Monitoring [0.5 marks]

11. Continuous monitoring [0.5 marks]
    • BP q5min × 30 minutes, then q15min
    • Continuous pulse oximetry
    • CTG monitoring for fetal status
    • Assess block height (target T10-L1)
    • Watch for complications (hypotension, fetal bradycardia, high block)"

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Examiner: The patient develops a severe headache 48 hours post-delivery. She describes it as frontal and occipital, worse when sitting up and better when lying flat. She had an inadvertent dural puncture during the CSE procedure. How do you manage this?

Candidate Response: [4 marks]**

"This presentation is classic for post-dural puncture headache (PDPH):

Diagnosis Confirmation [1 mark]

Clinical Features:

• Onset: 24-72 hours post-procedure (consistent with 48 hours)
• Position-dependent: Worse upright, better supine (pathognomonic)
• Location: Frontal and occipital (typical distribution)
• Associated symptoms: Likely nausea, photophobia, tinnitus (ask about these)
• History: Inadvertent dural puncture during CSE (high risk factor)

Differential:

• Tension headache (not position-dependent)
• Migraine (usually throbbing, associated symptoms different)
• Pre-eclampsia (hypertension, proteinuria — check BP, urine)
• Cerebral venous sinus thrombosis (rare, severe)

Management - Conservative [1.5 marks]

1. Bed rest:

• May provide temporary relief
• Not curative (doesn't patch dural hole)
• Prolonged bed rest may worsen headache when ambulating

2. Hydration:

• Oral or IV fluids
• Theoretical benefit (increases CSF production)
• Limited evidence for efficacy

3. Caffeine:

• Caffeine 500 mg IV or 300-500 mg PO
• Mechanism: Cerebral vasoconstriction, increased CSF production
• Evidence: Modest benefit in some studies
• Side effects: Jitteriness, insomnia
• Can repeat every 4-6 hours

4. Analgesics:

• Paracetamol 1 g q6h
• NSAIDs (ibuprofen 400 mg q8h) if not contraindicated
• Caffeine-containing analgesics (e.g., Panadeine Extra)

Management - Definitive (Epidural Blood Patch) [1.5 marks]

Indications for EBP:

• Severe headache limiting function
• Failed conservative management after 24-48 hours
• Patient preference for rapid resolution
• This patient: Severe, affecting ability to care for newborn

Technique:

1. Preparation:

   • Informed consent (explain procedure, risks)
   • IV access
   • Monitoring (BP, SpO₂)
   • Position: Sitting or lateral decubitus

2. Blood collection:

   • Aseptic technique
   • 18G IV cannula in antecubital vein
   • Collect 15-20 mL autologous blood

3. Epidural injection:

   • Insert epidural needle at L3-L4 or level of original puncture
   • Identify epidural space (loss of resistance)
   • Slowly inject autologous blood (15-20 mL)
   • Patient may feel pressure in back during injection

4. Post-procedure:

   • Lie flat for 30-60 minutes
   • Hydration
   • Analgesics PRN

Mechanism:

• Blood patches dural tear
• Forms clot over hole, seals CSF leak
• Restores CSF pressure

Success rate:

• 70-90% after single EBP
• 90-95% after repeat EBP if initial fails
• Usually performed 24-48 hours after onset (allow conservative trial first)

Risks:

• Back pain (transient)
• Infection (rare with aseptic technique)
• Repeat dural puncture (rare)
• Bradycardia (if excessive blood volume)

For this patient:

• Conservative trial: 24-48 hours of caffeine, hydration, analgesics
• If no improvement: Proceed with epidural blood patch
• Urgency: Not emergent, but should be performed within 1 week for best outcome
• Follow-up: Monitor for resolution, repeat EBP if needed (10-20% require second patch)"

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Examiner: How would your management differ if the patient was a Jehovah's Witness?

Candidate Response: [4 marks]**

"If this patient was a Jehovah's Witness, management requires modifications:

Preoperative Discussion [1 mark]

1. Informed refusal of blood products:

• Document explicit refusal of blood transfusion in medical record
• Witness signature: Patient, physician, witness
• Specific products refused: Red cells, plasma, platelets (may accept fractions)
• Explain risks: Potential for severe haemorrhage, cardiac arrest

2. Optimization strategies:

• Preoperative haemoglobin optimization:
  • Iron supplementation (IV iron sucrose or ferric carboxymaltose)
  • Erythropoietin (EPO) if time permits
  • Folate, B12 supplementation if deficient
• Minimize blood loss:
  • Tranexamic acid prophylaxis
  • Meticulous surgical haemostasis
  • Cell salvage if available

Intraoperative/Postoperative Management [2 marks]

3. Haemodynamic management:

• Permissive hypotension: Maintain SBP 80-90 mmHg until bleeding controlled
• Aggressive crystalloid resuscitation: Up to 5-6 L if needed
• Colloid use: Gelatin or starch solutions
• Vasopressor support: Norepinephrine, vasopressin to maintain MAP

4. Alternative blood products:

• Perfluorocarbon-based oxygen carriers: If available and patient consents
• Haemoglobin-based oxygen carriers: Oxyglobin (bovine) if available
• Acceptance varies: Some Witnesses accept, others refuse — confirm specific preferences

5. Cell salvage:

• Intraoperative cell saver: Collect, wash, reinfuse patient's own RBCs
• Usually accepted: Most Witnesses accept autologous blood
• Confirm acceptance: Individual variation exists

6. Acute normovolaemic haemodilution:

• Preoperative removal: 1-2 units blood immediately pre-op
• Replace with crystalloid: Maintain normovolaemia
• Reinfuse blood: At end of surgery or if bleeding occurs
• Usually accepted: Blood remains in circulation (continuous connection)
• Confirm acceptance: Some may refuse

Epidural Blood Patch Consideration [1 mark]

7. EBP and Jehovah's Witnesses:

• Autologous blood: Patient's own blood (usually acceptable)
• However: Some Jehovah's Witnesses may refuse even autologous blood if stored
• Clarify with patient:
  • "The blood patch uses your own blood, collected and immediately reinjected"
  • "It never leaves your body circulation entirely"
• Most accept EBP: Because it's autologous and immediate
• If refuses EBP: Conservative management only (prolonged bed rest, caffeine, fluids) — lower success rate

Communication and Support [0.5 marks]

8. Multidisciplinary approach:

• Ethics committee consultation: If concerns about patient safety vs. autonomy
• Religious liaison: Hospital chaplain or Witness liaison
• Family involvement: Discuss with family (with patient consent)
• Documentation: Thorough documentation of all discussions

9. Alternative strategies if EBP refused:

• Conservative management: Extended bed rest, aggressive hydration, caffeine
• Repeat EBP discussion: May change mind if conservative fails
• Acceptance of chronic headache: Some patients may prefer chronic headache over blood patch

Key Principles:

• Respect autonomy: Patient's right to refuse treatment
• Ensure understanding: Confirm informed refusal (not misunderstanding)
• Optimize alternatives: Maximize non-blood strategies
• Document thoroughly: All discussions, patient preferences, risks explained
• Maintain care: Continue all other aspects of care (analgesia, monitoring, support)"

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Examiner: What are the specific considerations for an Aboriginal woman requesting labour analgesia?

Candidate Response: [4 marks]**

"Labour analgesia for Aboriginal women requires culturally safe, individualized care:

Cultural Safety and Communication [1 mark]

1. Involvement of Aboriginal Health Workers:

• Aboriginal Midwives: Cultural mediators between medical team and patient
• Aboriginal Hospital Liaison Officers: Support communication, advocacy
• Language support: Interpreter if English not primary language
• Family involvement: Respect extended family decision-making processes

2. Communication strategies:

• Plain language: Avoid medical jargon, use visual aids
• Cultural context: Explain epidural in culturally appropriate terms
• Time: Allow extra time for questions and understanding
• Validation: Acknowledge and respect traditional birthing practices

Higher Risk Profile [1 mark]

3. Medical comorbidities: Aboriginal women have higher rates of conditions affecting labour analgesia:

• Gestational diabetes: 10-15% (vs. 5-8% non-Indigenous)

  • Higher risk of pre-eclampsia, macrosomia
  • Requires careful haemodynamic monitoring with neuraxial block

• Pre-eclampsia: 2-3 times higher incidence

  • Thrombocytopenia risk (contraindication to neuraxial)
  • Coagulopathy risk

• Obesity: Higher prevalence

  • Technical challenges with epidural insertion
  • Higher risk of hypotension, failed block
  • May require ultrasound guidance

• Anaemia: Higher prevalence

  • Lower physiological reserve
  • Higher hypotension risk with neuraxial block

Access and Technical Considerations [1 mark]

4. Geographic and access barriers:

• Remote communities: Limited access to epidural services
• Transfer requirements: May need early transfer for high-risk pregnancies
• Choice limitations: May not have full range of analgesic options
• Traditional practices: Some women may prefer traditional birth attendant

5. Technical considerations:

• Difficult insertion: Obesity and anatomical variations may make epidural technically challenging
• Ultrasound use: Consider ultrasound guidance for epidural placement
• CSE technique: May be preferred for rapid analgesia if technically difficult insertion anticipated
• Experienced operator: Ensure skilled anaesthetist available

Cultural Protocols and Support [1 mark]

6. Birthing on Country:

• Where possible: Support birth on traditional lands
• Cultural significance: Connection to land, ancestors, tradition
• Safety considerations: Balance with medical safety
• Telehealth support: Remote consultation with obstetric and anaesthetic teams

7. Family and community:

• Extended family presence: Important cultural practice during labour
• Support persons: Identify key family members patient wants present
• Cultural protocols: Respect for women's business, appropriate gender of care providers
• Discharge planning: Consider traditional healing practices alongside medical follow-up

8. Documentation and follow-up:

• Clear documentation: Analgesia plan, cultural considerations
• Postpartum care: Coordination with Aboriginal health services
• Remote follow-up: Telehealth, RFDS if returning to remote community
• Traditional healing: Document if patient wishes to incorporate traditional practices

Key Principles:

• Cultural safety first: Respect and incorporate cultural practices
• Shared decision-making: Involve patient, family, Aboriginal health workers
• Risk stratification: Higher medical risk requires careful planning
• Access equity: Work to overcome geographic barriers
• Holistic care: Medical + cultural + social considerations"

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Total: 25 marks

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