Anaesthetic Management of a Pregnant Patient with Severe Anaemia Posted for Elective LSCS

1. Evaluation

Definition and Classification

History

• Duration, onset, and likely aetiology (iron deficiency, folate/B12 deficiency, haemoglobinopathy, haemolytic, aplastic)
• Symptoms: dyspnoea at rest or minimal exertion, palpitations, chest pain, syncope - indicative of decompensation
• Dietary intake, pica, worm infestation (common causes in the developing world)
• Previous blood transfusions (alloimmunisation risk)
• Drug history (NSAIDs, haematinics compliance, antimalarials)
• Obstetric history: placenta praevia, previous PPH, grand multiparity

Physical Examination

• Pallor of conjunctivae, palms, mucous membranes - grades the clinical severity
• Signs of cardiac compensation: tachycardia, wide pulse pressure, hyperdynamic precordium, haemic murmur, cardiomegaly
• Features of high-output cardiac failure: bibasal crackles, raised JVP, peripheral oedema
• Jaundice (haemolytic cause), koilonychia/angular stomatitis (iron deficiency), neurological deficits (B12 deficiency)
• Airway assessment (Mallampati, thyromental distance, neck mobility - mandatory pre-LSCS)
• Spine assessment for neuraxial access

Investigations

• Complete blood count with indices (MCV, MCH, MCHC, RDW)
• Peripheral smear - morphology guides aetiology (hypochromic microcytes, target cells, sickle cells, spherocytes)
• Reticulocyte count
• Serum iron, TIBC, ferritin (iron stores), serum B12 and folate
• Hb electrophoresis if haemoglobinopathy suspected

• LFTs, RFTs, serum electrolytes
• Coagulation profile (PT, aPTT, platelet count) - haemolytic anaemias may coexist with thrombocytopenia (Evans syndrome, HELLP)
• Urine examination (urinary tract infection exacerbating anaemia; proteinuria)
• Blood grouping and crossmatch - hold 2-4 units packed red blood cells (PRBC) pre-operatively
• Indirect Coombs test if haemolytic or prior transfusion history

• ECG: tachycardia, signs of myocardial ischaemia, LVH (in long-standing anaemia)
• Echocardiography if signs of cardiac decompensation, suspected cardiomyopathy, or Hb <6 g/dL - assess LVEF, wall motion, pericardial effusion

• Cardiotocography (CTG) - fetal compromise is more likely when maternal Hb <6 g/dL due to reduced oxygen delivery
• Biophysical profile and umbilical artery Doppler if indicated

2. Preoperative Preparation

Treat the Underlying Cause

• Oral ferrous sulphate 200 mg three times daily (absorbed if gut normal; takes 6-8 weeks)
• Intravenous iron (ferric carboxymaltose 1000 mg single infusion, or iron sucrose 200 mg multiple sessions) is preferred when oral iron is not tolerated, malabsorption exists, time is limited (<4 weeks), or Hb <8 g/dL. IV iron increases Hb by approximately 1-2 g/dL over 2-4 weeks. Recent evidence confirms IV iron is superior to oral iron in restoring Hb in the perioperative obstetric patient. [PMID: 36794901]
• Folic acid 5 mg/day for megaloblastic component
• Vitamin B12 injection (1000 mcg IM) if deficient

Patient Blood Management (PBM) - Three Pillars

1. Optimise Hb preoperatively as above
2. Minimise intraoperative blood loss: meticulous surgical technique, oxytocin infusion, tranexamic acid 1 g IV before skin incision (now standard per WHO, evidence from WOMAN-2 trial)
3. Optimise physiological tolerance of anaemia: maintain normovolaemia, normothermia, adequate oxygenation

Transfusion Planning

• If Hb remains <7 g/dL despite treatment AND patient is symptomatic or surgery cannot be postponed further, consider pre-operative PRBC transfusion to achieve at least Hb 8-10 g/dL before elective LSCS
• Type and screen mandatory; 2-4 units PRBC crossmatched and available in theatre
• Discuss with haematologist in haemoglobinopathy (sickle cell: exchange transfusion may be needed to reduce HbS to <30%)
• Consent patient for blood and blood products including autologous/allogenic options

Multidisciplinary Team

• Obstetric anaesthetist, obstetrician, haematologist, neonatologist
• Intensive care/HDU bed should be arranged preoperatively if Hb <7 g/dL or signs of cardiac failure
• Intraoperative cell salvage setup should be considered - safe in obstetrics when leucodepletion filter is used (controversial but increasingly accepted)

Fasting and Aspiration Prophylaxis

• 6 hours solid food, 2 hours clear fluids
• Antacid prophylaxis (all obstetric patients undergoing LSCS, regardless of anaesthetic technique):
  • Ranitidine 150 mg orally the night before and 2 hours pre-op (or IV on arrival)
  • Metoclopramide 10 mg IV pre-op (promotility, reduces aspiration risk)
  • Sodium citrate 30 mL orally in theatre (non-particulate antacid - immediate acting)

3. Anaesthetic Management

General Principles

• Reduced functional residual capacity (FRC) and increased oxygen consumption - predisposing to rapid desaturation
• Full stomach from 18-20 weeks gestation (increased aspiration risk)
• Aortocaval compression in supine position - left uterine displacement is mandatory
• Airway oedema and friability - Mallampati grade often worsens in labour

• Reduced oxygen-carrying capacity with minimal reserve
• Compensatory high-output state (tachycardia, increased CO) - vasodilation or vasopressors must be used judiciously
• Risk of decompensation with even modest haemodynamic perturbation

Choice of Anaesthetic Technique

Neuraxial Anaesthesia - PREFERRED

• Avoids GA and its risks (difficult airway, failed intubation, pulmonary aspiration, fetal drug exposure)
• Reduces surgical blood loss compared to GA (sympathectomy reduces venous engorgement in pelvis)
• Maintains maternal airway reflexes
• Allows mother to be awake; no fetal drug transfer

• Hyperbaric bupivacaine 0.5%: 1.8-2.2 mL (10-11 mg) intrathecally at L3-L4 or L4-L5
• Fentanyl 15-25 mcg intrathecally (augments block, reduces dose of bupivacaine needed)
• Morphine 100-150 mcg intrathecally (postoperative analgesia - up to 24 hours)
• Target sensory level to T4 (loss of cold sensation at the 4th intercostal space level)

• Left uterine displacement throughout (15-degree left lateral tilt or wedge under right hip)
• Phenylephrine infusion is the vasopressor of choice (100 mcg/min starting infusion titrated to maintain systolic BP within 20% of baseline) - superior to ephedrine as it causes less fetal acidosis (Miller's Anesthesia, 10e, p. 8863)
• Crystalloid co-load 10-15 mL/kg Ringer's lactate rapidly at time of spinal injection - more effective than pre-load
• Colloid pre-load (500 mL colloid) may be considered but concerns exist about synthetic colloids; avoid large volumes in suspected cardiac dysfunction
• Avoid Trendelenburg positioning (reduces FRC further, worsens oxygenation)

• Slower onset allows more gradual titration - beneficial if cardiovascular compromise is present
• Catheter technique allows incremental dosing and extension if surgery is prolonged
• Combination spinal-epidural (CSE) is an excellent option: provides dense spinal block with ability to extend via epidural catheter
• Useful in cases where prolonged surgery is anticipated or there is concern about fixed cardiac output

General Anaesthesia - Reserved for Specific Indications

• Maternal refusal of neuraxial
• Coagulopathy (platelet count <80,000 or INR >1.5)
• Severe hypovolaemia
• Sepsis with haemodynamic instability
• Failed or inadequate neuraxial block
• Urgent/emergency (Category 1) caesarean

• Preoxygenation is absolutely mandatory: 3 minutes of tidal breathing with 100% O2 or 4 vital capacity breaths via tight-fitting mask
• In anaemia, FRC is already the only O2 reserve - do not compromise pre-oxygenation
• Rapid Sequence Induction (RSI) with cricoid pressure
  • Induction agent: thiopentone 4-5 mg/kg IV OR propofol 2-2.5 mg/kg IV
  • Muscle relaxant: succinylcholine 1.5 mg/kg IV (agent of choice for RSI in obstetrics)
  • If succinylcholine contraindicated: rocuronium 1.2 mg/kg IV with sugammadex available
• Ketamine 1-2 mg/kg IV is an alternative induction agent when haemodynamic compromise exists - maintains sympathetic tone, supports BP (avoid if severely hypertensive)
• Intubation with cuffed ETT (size 6.5-7.0); video laryngoscopy should be immediately available given the known risk of difficult intubation in obstetrics (1:300 cases)
• Maintenance: isoflurane/sevoflurane 0.5-1 MAC + 50% N2O in O2 or air; avoid high volatile agent concentrations (>1 MAC) before delivery as they relax uterus and increase blood loss
• Avoid N2O if severe anaemia and concern about tissue hypoxia - use air-O2 mix to maintain FiO2 > 0.5
• After delivery: increase anaesthetic depth, add opioids (fentanyl/morphine), oxytocin 5 IU slow IV then infusion 20-40 IU in 500 mL saline

Intraoperative Monitoring

Blood and Fluid Management

• Target Hb ≥ 8 g/dL intraoperatively in severe anaemia; lower threshold may worsen cardiac outcomes
• Crossmatched blood must be in theatre - ready to hang
• Cell salvage: set up intraoperatively, particularly if haemoglobinopathy, refusal of allogenic blood, or anticipated major blood loss (prior uterine scar, fibroids, placenta praevia)
• Tranexamic acid 1 g IV over 10 min at skin incision, repeated if ongoing blood loss at 30 minutes - reduces PPH by 31% (WOMAN trial; WOMAN-2 in elective CD)
• Oxytocin 5 IU slow IV bolus after cord clamping then 20-40 IU infusion (avoid rapid bolus in cardiac compromise - causes vasodilation and hypotension)
• Maintain normovolaemia with balanced crystalloids; avoid hypervolaemia (risk of pulmonary oedema in low-Hb states with compensatory high-output circulation)

Postoperative Management

• Recovery in HDU/ICU level care if Hb remained <7 g/dL at end of surgery or if haemodynamic instability
• Monitor SpO2, BP, urine output, blood loss, uterine tone continuously for at least 4 hours
• Supplemental oxygen (4-6 L/min via face mask) for at least 6-12 hours
• Reassess Hb and haematocrit 4-6 hours post-op; transfuse if Hb <7 g/dL with symptoms or <6 g/dL regardless
• Postoperative analgesia: multimodal (intrathecal morphine + paracetamol + diclofenac if no contraindication + tramadol if needed) - minimise systemic opioids to preserve respiratory drive
• IV iron therapy postpartum (ferric carboxymaltose) if oral iron not tolerated
• VTE prophylaxis: LMWH 6-12 hours after neuraxial block removal (anaemia is not a contraindication to VTE prophylaxis; timing guided by ASRA/OAA guidelines)
• Breastfeeding support and neonatal team review

4. Key Anaesthetic Considerations Summary

Recent Literature

• [PMID 36794901] - Wiesenack et al., Curr Opin Anaesthesiol (2023): Comprehensive review confirming IV iron as the preferred treatment for preoperative IDA in obstetric patients; intraoperative cell salvage is safe and effective in obstetrics.
• [PMID 38670490] - Moral et al., Rev Esp Anestesiol Reanim (2024): Delphi consensus recommending systemic preoperative anaemia screening and treatment protocols in all elective surgery.
• [CPOC UK Guidelines 2022]: Three-pillar Patient Blood Management framework for perioperative anaemia endorsed for all elective surgical specialties including obstetrics.