Anesthesiology APPLIED Exam › Obstetric anesthesia

Pre-eclampsia and eclampsia

Obstetric anesthesia·~5 min read· Physician-reviewed✓ Sourced · 4

Stem

A 24-year-old G1P0 at 34 weeks, 98 kg, is admitted with severe pre-eclampsia: blood pressure 172/114, headache, and 3+ proteinuria. Platelets are 88,000, down from 104,000 six hours ago; transaminases are mildly elevated. Magnesium has not yet been started. The obstetrician plans cesarean delivery within the hour for a non-reassuring tracing. Her airway is Mallampati 3 with a short neck.

Question

What are your priorities, and how will you anesthetize her for cesarean delivery?

Ideal answer

HeadlineA hypertensive emergency with end-organ risk and evolving HELLP: magnesium and blood-pressure control come before any anesthetic, then a spinal now.

Magnesium now; labetalol, hydralazine or oral nifedipine within 30–60 minutes, below the severe range,¹ many aiming for roughly 140–150 over 90–100.²
Repeat count, creatinine and coagulation panel now, because falling platelets with raised transaminases make this HELLP syndrome.
Spinal now, without waiting: delivery is inside the hour, she has no clinical bleeding or coagulopathy, and 88,000 is above the 70,000 at which SOAP judges hematoma risk likely very low; recheck the count within 6 hours.³
Measured fluid, phenylephrine for hypotension. Clinical coagulopathy instead: I weigh it against her airway and tell the obstetrician.
General only if unavoidable: blunt the pressor response to intubation, smaller tube.

Watch for: pulmonary edema, atony and postpartum seizures.

Breaking down the answer

Neuraxial first — it avoids laryngoscopy in an edematous airway and a pressor surge on at-risk cerebral vessels; spinal hypotension here is less severe than in healthy parturients and easily treated. Changes if: platelets below about 70,000, falling fast, or any clinical coagulopathy.³
Platelet threshold — without other risk factors: 70,000 or above likely very low risk; 50,000–70,000, competing risks (difficult airway) may justify proceeding; below 50,000, reasonable to avoid.³ It is an ABA sample stem.
Magnesium through delivery — the only drug that reduces eclampsia; the cost is a potentiated non-depolarizing block (rocuronium), uterine atony and, at toxic levels, loss of reflexes and respiratory depression. I check reflexes and urine output, calcium available.
Antihypertensive doses — labetalol 20 mg IV, then 40 and 80 mg at 10-minute intervals (hold for maternal pulse under 60);⁴ hydralazine 5–10 mg IV every 20 minutes.² Placental perfusion is not autoregulated, so not too low. Nitroglycerin or nicardipine infusions if refractory.
Fluids — intravascularly depleted but leaky: restrictive, measured boluses, because pulmonary edema is a leading cause of maternal death here.
General anesthesia — category 3 tracing with no working epidural, coagulopathy, or maternal instability. Video laryngoscope and a 6.0 tube; labetalol, esmolol or remifentanil for the intubation response, accepting that remifentanil may transiently depress the neonate.
Postpartum — eclampsia and pulmonary edema occur after delivery; magnesium continues for 24 hours, monitored.

Follow-up question

While you are positioning her for the spinal, she has a generalized tonic-clonic seizure, and the fetal heart rate falls to 70 bpm.

What do you do?

Follow-up answer

HeadlineAn eclamptic seizure; I call for help, protect her and the airway, and give magnesium.

100% oxygen and left uterine displacement; magnesium 4–6 g bolus if she is not loaded, an additional 2 g if she is, lorazepam or a small dose of propofol if it continues. Most eclamptic seizures are self-limited: I intubate only if she fails to protect her airway or does not wake. I reassess the fetal heart rate: fetal bradycardia during the seizure usually recovers as the mother recovers, so no crash cesarean under general anesthesia on a tracing that is already improving. Once stable, delivery timing with the obstetrician.

Pitfalls that cost points

Launching into the anesthetic plan before saying you would control the blood pressure and confirm magnesium.
Quoting a platelet number without the trend or the clinical context; examiners want the reasoning, not the cutoff.
Treating the eclamptic seizure as an indication for immediate intubation and crash cesarean.
Over-resuscitating with fluid because the patient is "dry" and then being asked about the pulmonary edema.

Rapid-fire

Q: Why is spinal hypotension less of a problem in pre-eclampsia? A: Sympathetic tone is already high and the vasculature is less responsive; the fall in pressure is smaller and responds to phenylephrine.

Q: Why not ketamine for induction? A: It raises blood pressure and intracranial pressure in a patient already at risk of cerebral hemorrhage.

Q: What is the magnesium therapeutic range and the first sign of toxicity? A: About 4–8 mg/dL; loss of patellar reflexes, followed by respiratory depression above roughly 12 mg/dL. Calcium gluconate 1 g reverses it.

Q: Why avoid ergot alkaloids for atony here? A: Methylergonovine causes severe hypertension; I use oxytocin, then carboprost if there is no asthma.

Numbers to know

Item	Value
Severe-range blood pressure	≥160 systolic or ≥110 diastolic⁴
Magnesium load / maintenance	4–6 g IV over 20–30 min, then 1–2 g/h²
Magnesium toxicity	Reflexes lost ~10 mg/dL; respiratory depression ~12–15 mg/dL
Labetalol	20, 40, 80 mg IV every 10 min; max 300 mg/24 h⁴
Hydralazine	5–10 mg IV every 20 min; max 25 mg/24 h²
Neuraxial platelet guidance	≥70,000: likely very low risk; 50,000–70,000: weigh risks; <50,000: reasonable to avoid³

Sources

1.ACOG Committee Opinion No. 767: Emergent Therapy for Acute-Onset, Severe Hypertension (abstract) · ACOG (via OPQIC), 2019 · opqic.org
2.How to Diagnose and Manage Hypertensive Disorders in Pregnancy · ACEP Now · acepnow.com
3.SOAP Interdisciplinary Consensus Statement on Neuraxial Procedures in Obstetric Patients With Thrombocytopenia · SOAP (Bauer et al., Anesth Analg), 2021 · soap.org
4.Labetalol algorithm for severe hypertension in pregnancy/postpartum · Kansas Perinatal Quality Collaborative, 2025 · kansaspqc.kdhe.ks.govAdapted from the Safe Motherhood Initiative algorithm (rev. 2020).

Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.