Anesthesiology APPLIED Exam › Obstetric anesthesia

Pre-eclampsia and eclampsia

T1Obstetric anesthesia·1024 words · ~6 min read·v0.1✓ Sourced · 4DRAFT

Why examiners ask this

Pre-eclampsia forces you to hold three competing problems at once: a hypertensive, intravascularly depleted patient who may be coagulopathic, a fetus that may need to come out in minutes, and an airway that is swollen and will bleed. It is one of the most reliable additional topics because every answer tests judgment (neuraxial or general?) and adaptability (the blood pressure is 190/120, now what?). The ABA's own sample stem uses exactly this scenario.

The 60-second answer

This is a hypertensive emergency with end-organ risk, so my first priorities are seizure prophylaxis and blood-pressure control before any anesthetic. I confirm magnesium is running, and treat a systolic pressure of 160 or more or diastolic of 110 or more with labetalol, hydralazine or oral nifedipine within 30–60 minutes,¹ bringing it below the severe range (many aim for roughly 140–150 over 90–100),² and check a platelet count, creatinine, transaminases and a coagulation panel if the platelets are low or the picture is severe. For cesarean delivery I prefer neuraxial anesthesia, provided the platelet count is adequate and falling slowly and there is no coagulopathy, because it avoids the hypertensive response to laryngoscopy and a potentially difficult airway. I use a spinal or an existing epidural, with careful fluid loading and phenylephrine for hypotension. If a general anesthetic is unavoidable, I blunt the pressor response to intubation and plan for a smaller tube.

Decision points and the "why"

Neuraxial first — it avoids laryngoscopy in a patient whose airway is edematous and whose cerebral vessels are at risk from a pressor surge; spinal hypotension in pre-eclampsia is less severe than in healthy parturients and is easily treated. I change my mind if the platelet count is below about 70,000, is falling fast, or there is any clinical coagulopathy; with HELLP I recheck the count within 6 hours of the block.³
Platelet threshold — the SOAP consensus judges hematoma risk at 70,000 or above (without other risk factors) likely very low; between 50,000 and 70,000 competing risks such as a difficult airway may justify proceeding; below 50,000 it is reasonable to avoid neuraxial.³
Magnesium continues through delivery — it is the only drug that reduces eclampsia; the cost is potentiated non-depolarizing block, uterine atony and, at toxic levels, loss of reflexes and respiratory depression. I check reflexes and urine output, and have calcium available.
Antihypertensive choice — labetalol 20 mg IV, then 40 and 80 mg at 10-minute intervals (maximum 300 mg in 24 hours, hold for maternal pulse under 60),⁴ or hydralazine 5–10 mg IV every 20 minutes (maximum 25 mg in 24 hours);² I avoid dropping the pressure too far because placental perfusion is not autoregulated. Nitroglycerin or nicardipine infusions for refractory cases.
Fluids — these patients are intravascularly depleted but leak; I give restrictive, measured boluses and watch for pulmonary edema, which is a leading cause of maternal death in this condition.
General anesthesia only when needed — category 3 tracing with no working epidural, coagulopathy, or maternal instability. I then plan for a difficult airway: video laryngoscope and a 6.0 tube at hand, and I attenuate the intubation response with labetalol, esmolol, or remifentanil, accepting that remifentanil may transiently depress the neonate.
Postpartum vigilance — eclampsia and pulmonary edema occur after delivery; magnesium continues for 24 hours and I keep the patient monitored.

The complication they will inject

She seizes during labor, or on the table. I call for help, protect her and the airway, give 100% oxygen and left uterine displacement, and treat the seizure with magnesium: a 4–6 g bolus if she is not already loaded, or an additional 2 g if she is, with lorazepam or a small dose of propofol if the seizure continues. Most eclamptic seizures are self-limited; I do not rush to intubate unless she fails to protect her airway or does not wake. I then reassess the fetus, because fetal bradycardia during the seizure usually recovers as the mother recovers, and I do not proceed to an emergency cesarean under general anesthesia on a tracing that is already improving. Once stable, I decide on 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.
Forgetting that magnesium potentiates rocuronium and that uterine atony becomes more likely.

Rapid-why

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.