Severe Preeclampsia With a Platelet Count of 84,000 and a Category II Tracing
A 31-year-old primigravida at 34+2 weeks presents with a 3-day history of frontal headache and visual scintillations. Blood pressure is 178/112 mmHg on two readings, and she has 3+ proteinuria. She has received two doses of intramuscular betamethasone and an intravenous magnesium sulphate loading dose followed by infusion. Bloods: platelets 84 × 10⁹/L, AST 96 U/L, ALT 88 U/L, creatinine 106 µmol/L, haemoglobin 118 g/L, fibrinogen 4.1 g/L, PT and aPTT normal. The cardiotocograph shows a baseline of 165/min with recurrent late decelerations and reduced variability. Airway examination: BMI 36, Mallampati 3, mild facial and tongue oedema, 2 cm thyromental distance, full dentition. The obstetrician requests category-2 caesarean delivery and asks whether you will 'do a spinal'. The platelet count was 132 × 10⁹/L twelve hours earlier.
1. How do you decide between neuraxial anaesthesia and general anaesthesia with a platelet count of 84 × 10⁹/L, and what information changes your answer?
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A platelet count of 84 × 10⁹/L with normal PT/aPTT and a normal fibrinogen is generally acceptable for neuraxial anaesthesia in obstetrics - but the trend, not the number, drives my decision.
The reasoning:
- Threshold: for neuraxial techniques in pregnancy, a count above roughly 70–75 × 10⁹/L with no other coagulopathy is widely accepted, because the absolute risk of spinal epidural haematoma is very low and the alternative (general anaesthesia) carries its own substantial risk in a preeclamptic airway.
- The fall from 132 to 84 in 12 hours is the concerning feature. This is either HELLP evolution or consumptive change and can continue to fall over the next few hours. I would repeat the count immediately before the block (point-of-care if available), check the film for schistocytes, and check fibrinogen and liver enzymes again.
- Technique choice: a single-shot spinal with a fine-gauge pencil-point needle, one pass, no catheter left in situ. An epidural catheter left indwelling in a patient whose platelets may drop to 40 by the evening is a liability; a single shot has no indwelling foreign body and no ongoing risk of catheter-related bleeding.
- General anaesthesia is my alternative, not my default. She has tongue oedema, a Mallampati 3 airway, and severe hypertension - a genuinely difficult intubation combined with a pressor response to laryngoscopy is a bad pairing, and failed intubation in obstetric general anaesthesia remains a leading cause of anaesthetic death.
What would change my answer to general anaesthesia: platelets below ~50 × 10⁹/L or falling rapidly, any prolongation of PT/aPTT, fibrinogen falling, active bleeding, a technically failed or traumatic spinal, or an immediate-delivery emergency where there is no time to recheck.
2. Mid-spinal preparation the fetal heart rate falls to 70/min with a scalp pH of 7.15, and the obstetrician calls for immediate delivery. Walk through your management, including induction if you must convert to general anaesthesia.
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First: do not abandon a neuraxial technique that is already working unless there is a hard reason to. A spinal can be sited and the baby delivered within 5–8 minutes if the team moves; general anaesthesia in this airway is the higher-risk path and should be reserved for failure or a coagulation result that forbids neuraxial.
If neuraxial: left uterine displacement, oxygen, rapid siting of a single-shot spinal with hyperbaric bupivacaine plus fentanyl, phenylephrine or noradrenaline infusion running before incision to prevent spinal hypotension (which worsens fetal bradycardia), and delivery within minutes. Aortocaval compression and maternal hypotension are the commonest reversible causes of a sudden fetal bradycardia in this setting.
If I must convert to general anaesthesia:
- Preparation: ramped position, difficult airway trolley, two suction units, video-laryngoscope, a second skilled operator, smaller tube (6.5), and the obstetric team aware of a possible delay in incision.
- Preoxygenation for 3 minutes to end-tidal oxygen >90%, with nasal apnoeic insufflation.
- Blunting the pressor response: alfentanil 10–20 µg/kg or remifentanil, plus labetalol or esmolol and magnesium already on board; target systolic <160 before laryngoscopy to reduce the risk of intracranial haemorrhage.
- RSI: thiopentone 4–5 mg/kg or propofol, suxamethonium 1–1.5 mg/kg (magnesium potentiates non-depolarising blockers, so reduce rocuronium to 0.6 mg/kg if used), cricoid pressure, intubate, confirm with capnography.
- After delivery: oxytocin as an infusion, not a bolus (boluses cause hypotension and tachycardia); avoid ergometrine; maintain magnesium for 24 hours; keep invasive or close blood pressure monitoring and treat systolic >160 with labetalol or nifedipine.
3. Describe your postoperative analgesic and monitoring plan, including what you are watching for with magnesium and with platelets.
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Analgesia: multimodal, neuraxial where possible, and opioid-sparing but not opioid-averse.
- After spinal: intrathecal morphine 100–150 µg (diamorphine 300 µg where used) gives 18–24 hours of analgesia; prescribe regular paracetamol, and add oxycodone or a fentanyl PCA for breakthrough. Avoid NSAIDs - platelets are already low and creatinine is elevated; both renal and platelet effects argue against them.
- After general anaesthesia: intravenous fentanyl PCA plus paracetamol; a transversus abdominis plane or rectus sheath block with a low concentration of local anaesthetic is a useful adjunct if coagulation is normal. Avoid intramuscular injections.
- Monitoring: hourly blood pressure, urine output with a catheter, strict fluid balance, and neurological observations. Continue magnesium sulphate for 24 hours post-partum; check magnesium levels if renal function is impaired, since magnesium is renally cleared and toxicity is a real risk. Watch for loss of deep tendon reflexes, respiratory rate below 12/min, oliguria, and confusion - the antidote is calcium gluconate 10% 10 mL.
- Platelets: repeat 6–12 hourly in the first 24 hours. HELLP can worsen after delivery before it improves. A falling count with bleeding, haematuria, or oozing from the wound needs haematology input, blood product planning, and consideration of dexamethasone per local protocol.
- Other post-partum risks: postpartum haemorrhage (uterine atony is common with magnesium and oxytocin), and hypertensive urgency - continue labetalol or nifedipine with a defined threshold for treatment. Document a clear escalation plan and ensure the ward knows the spinal morphine may cause delayed respiratory depression on the second night.