HELLP Syndrome: Anaesthesia Diagnosis & Management

1. Definition & Classification

2. Diagnosis

• Epigastric or right upper quadrant (RUQ) pain (most common complaint, ~90%)
• Nausea, vomiting, malaise — often misdiagnosed as gastroenteritis or flu
• Hypertension and proteinuria may or may not be present
• Onset: 70% antepartum (usually >28 weeks); 30% postpartum (within 48 hours of delivery)

• Acute fatty liver of pregnancy (AFLP) — overlaps significantly; distinguished by hypoglycaemia, coagulopathy (PT/APTT prolonged), ammonia elevation
• TTP/HUS — more severe thrombocytopenia, less hepatic involvement
• Gestational thrombocytopenia — platelets rarely <70,000, no liver involvement
• ITP — no elevated liver enzymes or hemolysis
• Antiphospholipid antibody syndrome

• FBC (platelet count + trend)
• LFTs (AST, ALT, LDH, bilirubin)
• Renal function (creatinine, uric acid)
• Coagulation screen (PT, aPTT, fibrinogen, D-dimers) — DIC develops in ~20%
• Peripheral blood smear
• Uric acid, glucose (to exclude AFLP)

3. Anaesthetic Considerations

A. Pre-anaesthetic Assessment

• Generalised oedema including airway oedema is common; anticipate a difficult airway
• Facial oedema, pharyngeal/laryngeal oedema can make laryngoscopy unpredictable
• Grade the airway carefully (Mallampati, neck mobility, mouth opening)
• Have a difficult airway plan (video laryngoscope, smaller ETT sizes, surgical airway ready)

• Check platelet count — and the trend (falling count is more dangerous than an absolute value)
• Check PT, aPTT, fibrinogen — DIC must be excluded before neuraxial anaesthesia
• Platelet function may be impaired even with adequate counts in preeclampsia/HELLP
• TEG/ROTEM can provide real-time global coagulation data and guide therapy where available

• Impaired drug metabolism; consider reduced doses of agents with hepatic clearance
• Risk of subcapsular hepatic haematoma → avoid abdominal pressure/compression
• Coagulopathy secondary to hepatic dysfunction can compound thrombocytopenia

• Progressive renal insufficiency (creatinine >1.1 mg/dL) alters drug elimination
• Monitor urine output (target >0.5 mL/kg/hr); avoid nephrotoxic agents

• Systemic vasoconstriction with relative intravascular hypovolaemia despite peripheral oedema
• Increased SVR → acute pulmonary oedema risk, especially with fluid loading
• CVP monitoring may be required in severe cases; consider arterial line for beat-to-beat BP

• Magnesium potentiates non-depolarising neuromuscular blocking agents (e.g., rocuronium) — reduce dose, monitor with neuromuscular blockade monitoring
• Can cause respiratory depression, loss of deep tendon reflexes, and cardiac arrest at toxic levels
• Calcium gluconate (10 mL of 10%) must be immediately available as antidote

B. Regional Anaesthesia — Neuraxial Techniques

• Platelet count of ≥70,000/mm³ with stable or improving trend and no clinical bleeding = acceptable for neuraxial block
• No test of platelet function or single platelet count universally predicts neuraxial haematoma
• In a large case series review: obstetric spinal haematoma was 0.6/100,000 vs 18.5/100,000 in non-obstetric patients — obstetric patients have inherent prothrombotic protection
• Two reported spinal haematoma cases in obstetric populations — both had HELLP syndrome
• TEG/ROTEM add information but no validated threshold variable currently exists

• Previous concern that spinal causes more severe hypotension in preeclampsia has been disproven
• Women with severe preeclampsia had less hypotension with spinal (17%) vs. healthy controls (53%) in one comparison study
• Vasopressors (phenylephrine or ephedrine) must be immediately available regardless of technique
• α-agonists (phenylephrine) are preferred pressor agents; avoid excessive fluid preloading due to pulmonary oedema risk

• Difficult/concerning airway examination
• Lengthy induction of labour anticipated
• Rarity of neuraxial haematoma in obstetric patients

• Clinical signs of active bleeding (oozing at IV sites, gums)
• Rapidly falling platelet count
• Overt DIC (coagulation screen severely deranged)
• Need for urgent/emergency caesarean
• Reassuring airway with no anticipated difficulty

C. General Anaesthesia (when indicated)

1. Hypertensive response to laryngoscopy — most critical issue
   • Use an adjunct to RSI: esmolol, labetalol, nicardipine, remifentanil, or nitroglycerin
   • At least one must be drawn up and ready before induction
   • Target SBP <160 mmHg — haemorrhagic stroke risk is predominantly from systolic hypertension (93% of strokes in severe preeclampsia were haemorrhagic; all had SBP >155 mmHg)
2. Difficult airway management
   • Airway oedema can be severe and progressive; always have video laryngoscopy available
   • Use a smaller ETT (6.0–6.5 mm)
   • LMA documented as rescue device if intubation fails
   • Have a failed intubation protocol in place
3. Magnesium–muscle relaxant interaction
   • Magnesium synergises with rocuronium and other NDMRs → prolonged block, difficult extubation
   • Monitor neuromuscular function; do NOT reverse with sugammadex without adequate train-of-four response
   • If patient shows pre-induction weakness (cannot hold head off pillow for 5 seconds), consider pausing magnesium infusion (though ACOG recommends continuing through caesarean delivery)
   • Post-op respiratory depression risk — keep ventilated until strength criteria met
4. Uterine atony risk
   • Magnesium sulfate is a uterotonic antagonist — expect atony post-delivery
   • Additional uterotonic agents essential: misoprostol, carboprost (Hemabate), ergometrine, tranexamic acid
   • Synergism with oxytocin infusion should be exploited

D. Haematologic Management

• Platelet count <20,000–30,000/mm³ → transfuse before delivery
• Platelet count <50,000/mm³ → transfuse before caesarean delivery
• Transfuse to maintain ≥50,000/mm³ for surgical delivery (higher targets if active haemorrhage or DIC)

• Treat with FFP (target INR <1.5) and cryoprecipitate (target fibrinogen >1.5 g/L)
• Massive transfusion protocol: aim for 1:1:1 ratio of PRBCs : FFP : platelets
• Fibrinogen level is the best early predictor of developing coagulopathy

• Rupture risk intraoperatively and postoperatively
• Avoid abdominal external pressure; manage in MDT setting with hepatobiliary/vascular surgery backup

E. Postpartum Anaesthetic Management

• Most HELLP resolves within 48–72 hours of delivery — monitor platelet trend (nadir typically at 24–48 hours postpartum)
• Thrombocytopenia may persist for several days — time epidural catheter removal with platelet trend (same thresholds as insertion apply)
• Fluid management: Mobilisation begins in first 24 hours → greatest pulmonary oedema risk window; monitor urine output, SpO₂, lung auscultation
• BP control: Continue antihypertensive therapy postpartum; watch for rebounding hypertension
• Seizure risk: ~30% of eclamptic seizures occur postpartum; continue magnesium prophylaxis for 24–48 hours
• Postpartum headache: Include late-onset preeclampsia/HELLP in differential (alongside PDPH and cerebral venous thrombosis)
• Dexamethasone: Some evidence for accelerating platelet recovery with IV corticosteroids (dexamethasone 10 mg IV q12h postpartum), though routine use remains controversial

4. Summary Decision Algorithm

HELLP Suspected
     ↓
Labs: CBC, LFTs, LDH, coags, peripheral smear
     ↓
Confirm diagnosis → Notify MDT (Obstetrics, Anaesthesia, Haematology, NICU)
     ↓
Delivery planning
     ↓
Platelets ≥70,000 + stable trend + no DIC → Neuraxial preferred
Platelets <50,000 OR DIC OR rapid fall → General anaesthesia
     ↓
If GA: Prepare for difficult airway + attenuate laryngoscopy response + magnesium interaction
     ↓
Postpartum: Monitor platelets q6–12h, fluid balance, BP, seizure prophylaxis
     ↓
Epidural catheter removal when platelets trending up + above safe threshold

• Miller's Anesthesia, 2-Volume Set, 10e — Hypertensive Disorders & Coagulopathies in Obstetric Anaesthesia
• Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice — Preeclampsia, Eclampsia, and HELLP; Obstetric Anaesthesia