Preeclampsia and eclampsia nursing: complete reference guide

Preeclampsia complicates 2–8% of all pregnancies and is among the leading causes of maternal and perinatal mortality worldwide. In the United States, hypertensive disorders of pregnancy account for roughly 6–8% of pregnancy-related deaths — deaths that are largely preventable with early recognition and skilled nursing response. For nursing students, preeclampsia represents one of the most heavily tested obstetric topics on NCLEX, appearing in scenarios that test your knowledge of diagnostic criteria, magnesium sulfate toxicity, and emergency seizure management. This reference covers everything you need: the pathophysiology behind why the condition progresses as it does, how to recognize it across its clinical spectrum, how to manage magnesium therapy safely, and what the NCLEX consistently tests.

Quick reference: preeclampsia spectrum at a glance

Pathophysiology: why preeclampsia develops and progresses

Understanding why preeclampsia causes what it causes is more useful for NCLEX than memorizing a list of symptoms. The disorder originates in abnormal placentation.

In a normal pregnancy, extravillous trophoblast cells invade the maternal spiral arteries of the uterus during the first and second trimester. This invasion remodels the arteries from narrow, high-resistance vessels into wide, low-resistance conduits that can supply the growing placenta. In preeclampsia, this remodeling fails. The spiral arteries remain narrow and high-resistance, leading to chronic placental ischemia.

In response to ischemia, the placenta releases a cascade of anti-angiogenic factors — most importantly sFlt-1 (soluble fms-like tyrosine kinase-1), which neutralizes circulating vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). The result is widespread maternal endothelial dysfunction. Endothelial dysfunction explains essentially all of the clinical manifestations:

• Hypertension: vasospasm from loss of normal endothelial vasodilatory tone
• Proteinuria: glomerular endotheliosis — the glomerular capillary endothelium swells, increasing permeability to protein
• Cerebral involvement: disruption of cerebrovascular autoregulation, cerebral edema, and lowered seizure threshold — the mechanism for eclamptic seizures
• Hepatic involvement: hepatic sinusoidal obstruction from fibrin deposition causes the epigastric/RUQ pain and elevated liver enzymes seen in severe disease
• Thrombocytopenia: microangiopathic consumption of platelets as they encounter damaged endothelium

The seizure that defines eclampsia is therefore not primarily an electrical discharge disorder — it results from cerebrovascular injury and loss of autoregulation. This is why magnesium sulfate, which acts on the CNS rather than as an antihypertensive, is the preferred seizure prophylaxis and treatment.

Diagnostic criteria: what ACOG 2013 changed

ACOG revised the diagnostic criteria for preeclampsia in 2013 (reaffirmed in Practice Bulletin 222, 2020), and the change matters for NCLEX. Proteinuria is no longer required to diagnose preeclampsia.

Preeclampsia is diagnosed when a pregnant patient at ≥20 weeks gestation has:

• BP ≥140 mmHg systolic OR ≥90 mmHg diastolic on at least 2 occasions, 4 hours apart

AND at least one of the following:

• Proteinuria ≥300 mg in a 24-hour collection, or protein:creatinine ratio ≥0.3, or urine dipstick 2+
• OR any severe feature (see below) even without proteinuria

Severe features (any one qualifies as severe preeclampsia):

• Systolic BP ≥160 or diastolic BP ≥110 on 2 occasions 15 minutes apart
• Thrombocytopenia: platelet count <100,000/μL
• Renal insufficiency: serum creatinine >1.1 mg/dL, or doubling from baseline
• Impaired liver function: AST or ALT >2× normal upper limit, or severe RUQ/epigastric pain unresponsive to medication
• Pulmonary edema
• New-onset headache unresponsive to medication, or visual symptoms

The BP cutoff matters: ≥140/90 defines the condition; ≥160/110 defines the severe range requiring urgent antihypertensive treatment.

Clinical presentation: recognizing the spectrum

Symptoms follow directly from the pathophysiology. Endothelial dysfunction affects every organ system, so presentation can be subtle early and rapidly life-threatening.

Central nervous system: Headache (often occipital, severe, persistent) and visual disturbances are the most NCLEX-relevant symptoms. Visual changes may include blurred vision, photophobia, or scotomata — visual blind spots caused by retinal vasospasm. Hyperreflexia (brisk DTRs) and clonus indicate CNS irritability and predict seizure risk. Assess patellar reflexes at every nursing encounter during MgSO4 therapy.

Hepatic: Right upper quadrant or epigastric pain from hepatic capsule distension is a warning sign. It often precedes either an eclamptic seizure or HELLP syndrome and should be reported immediately.

Renal: Oliguria (<30 mL/hr, or <500 mL/24 h) signals worsening renal involvement and is a key nursing monitoring parameter.

Edema: Generalized edema — including non-dependent edema of the face and hands — is associated with preeclampsia, though non-edematous preeclampsia occurs. Edema alone is insufficient for diagnosis.

Nursing assessment and monitoring

Structured, frequent assessment is the primary nursing intervention in preeclampsia. The purpose is early detection of clinical deterioration.

Blood pressure monitoring:

• During active MgSO4 infusion: BP every 15 minutes
• Between assessments: continuous fetal monitoring; maternal vital signs per unit protocol (minimum hourly)
• Document both readings required for severe-range BP (two readings 15 minutes apart) before administering antihypertensives, unless the clinical picture is urgent

Neurological assessment:

• Assess deep tendon reflexes (patellar) before each MgSO4 dose adjustment and at least every hour during infusion
• Grade reflexes: 0 = absent, 1+ = diminished, 2+ = normal, 3+ = brisk, 4+ = clonus
• Check for ankle clonus: briskly dorsiflex the foot and hold — sustained rhythmic oscillation indicates CNS irritability
• Report absent DTRs immediately — this is the earliest sign of magnesium toxicity

Urine output:

• Maintain urinary catheter for accurate hourly measurement
• Oliguria threshold: <30 mL/hr (or <0.5 mL/kg/hr) — report and consider fluid challenge or provider reassessment
• Oliguria during MgSO4 infusion is particularly concerning because magnesium is renally cleared; reduced clearance increases toxicity risk

Fetal monitoring:

• Continuous electronic fetal monitoring during labor and during MgSO4 infusion
• Variability may be reduced (MgSO4 crosses the placenta and can mildly suppress fetal CNS)
• Late decelerations or absent variability require immediate provider notification

Respiratory monitoring:

• Respiratory rate before each MgSO4 assessment — rate <12 breaths/min is a toxicity threshold requiring infusion hold
• Pulse oximetry continuous during infusion

Magnesium sulfate therapy

Magnesium sulfate (MgSO4) is the cornerstone of seizure prophylaxis and treatment in preeclampsia. It is the single most NCLEX-tested pharmacologic topic in this clinical area.

Mechanism: Magnesium is a physiologic calcium antagonist. It crosses the blood-brain barrier and acts as a CNS depressant, raising the seizure threshold by blocking NMDA receptors and reducing neuronal excitability. Magnesium also causes peripheral vasodilation (which produces a mild BP-lowering effect) and relaxes smooth muscle.

Critical distinction for NCLEX: Magnesium sulfate is not an antihypertensive. Its purpose is seizure prophylaxis. Antihypertensive agents are used separately to control BP.

Dosing:

• Loading dose: 4–6 g IV infused over 15–20 minutes
• Maintenance dose: 1–2 g/hr continuous IV infusion
• Duration: throughout labor and 24–48 hours postpartum (eclampsia risk continues after delivery)

Therapeutic serum range: 4–7 mEq/L (magnesium levels sufficient to prevent seizures without toxicity)

Antidote: Calcium gluconate 1 g IV (10 mL of a 10% solution) administered slowly over 3 minutes. This must be at the bedside for every patient receiving MgSO4. Calcium gluconate directly antagonizes the effect of magnesium at the cellular level.

Assessment before and during infusion (COAT mnemonic):

• Clonus/DTRs present? (absent = stop)
• Output adequate? (<30 mL/hr = hold, reassess — renal clearance is impaired)
• Airway/respirations? (RR <12 = stop)
• Toxicity signs? (flushing and warmth are expected; somnolence, absent DTRs, RR <12 are not)

Antihypertensive management

Treating hypertension in preeclampsia serves a different goal than treating it in non-pregnant patients. The target is not normalization — it is prevention of end-organ damage (stroke, abruption, cardiac failure) while maintaining adequate uteroplacental perfusion.

When to treat: ACOG recommends initiating antihypertensive therapy when systolic BP is ≥160 or diastolic BP is ≥110 sustained for 15–30 minutes. This is a medical urgency. The goal is to reduce BP to 140–150/90–100 mmHg — not to normal values.

First-line agents (ACOG preferred):

• Labetalol: 20 mg IV bolus; can repeat 40 mg, then 80 mg q10 min to a maximum 300 mg cumulative dose. Alpha and beta blockade. Avoid in asthma or bradycardia.
• Hydralazine: 5–10 mg IV bolus q20 min. Direct arteriolar vasodilator. Associated with maternal hypotension and reflex tachycardia.
• Nifedipine (oral): 10–20 mg immediate-release PO q20–30 min. Calcium channel blocker. Used when IV access is unavailable or as step-down therapy. Caution when combined with MgSO4 — may potentiate hypotension and neuromuscular blockade.

Contraindicated in pregnancy:

• ACE inhibitors (captopril, lisinopril) — fetal renal toxicity; teratogenic in second and third trimesters
• Angiotensin receptor blockers (ARBs) — same mechanism of fetal harm
• Atenolol — associated with fetal growth restriction

HELLP syndrome

HELLP syndrome represents the most severe end of the preeclampsia spectrum. The name is a diagnostic triad, and each component has specific laboratory thresholds that are tested on NCLEX.

HELLP criteria (Tennessee Classification, Mississippi variant referenced in ACOG):

• H — Hemolysis: LDH >600 U/L; abnormal peripheral smear (schistocytes, burr cells); elevated bilirubin
• EL — Elevated liver enzymes: AST >70 U/L and/or ALT >70 U/L (some criteria use 2× upper limit of normal)
• LP — Low platelets: <100,000/μL

Clinical features that distinguish HELLP from severe preeclampsia:

• Nausea, vomiting, and malaise — often the presenting symptoms
• Severe RUQ or epigastric pain from hepatic capsule distension
• Jaundice in advanced cases
• DIC (disseminated intravascular coagulation) — a life-threatening complication; monitor fibrinogen, PT/INR, and D-dimer
• Spontaneous hepatic rupture (rare but catastrophic)

Key nursing actions in HELLP:

• Serial CBC, LFTs, and coagulation studies (every 6–12 hours minimum)
• Type and crossmatch — transfusion may be required for platelets <20,000 or <50,000 with bleeding
• Corticosteroids (betamethasone) if <34 weeks for fetal lung maturity — delivery will be required
• Delivery is the only definitive treatment at any gestational age

HELLP can present postpartum — onset within 48 hours of delivery is common, and new HELLP after delivery should be considered in any postpartum patient with malaise, nausea, and elevated LFTs.

Delivery and postpartum considerations

Delivery of the fetus and placenta is the only definitive treatment for preeclampsia. All other management is supportive and temporizing.

Timing:

• Preeclampsia without severe features: delivery at 37 weeks
• Preeclampsia with severe features: delivery at 34 weeks; if deteriorating or if maternal/fetal status is unstable, deliver at any gestational age
• Eclampsia: delivery after maternal stabilization — seizure management and airway first, then delivery planning

Postpartum magnesium: MgSO4 is continued for 24–48 hours after delivery. This is not optional. The eclampsia risk in the postpartum period is as high as — and may exceed — the antepartum risk. Approximately 25–40% of eclamptic seizures occur postpartum.

Late postpartum eclampsia: Eclampsia can occur up to 4 weeks after delivery. Educate postpartum patients to return immediately for:

• Severe or persistent headache
• Visual changes
• Right upper quadrant pain
• Facial or hand swelling that develops after discharge
• Seizure activity

BP management postpartum: BP commonly spikes 3–6 days postpartum (due to fluid redistribution as interstitial edema remobilizes). Antihypertensive therapy is frequently required for 1–2 weeks after discharge. NSAIDs (ibuprofen), commonly used for postpartum pain, can raise BP in preeclamptic patients and should be used cautiously or avoided if BP remains elevated.

NCLEX tips: highest-yield testable points

1. Magnesium toxicity sequence — loss of DTRs comes first. On NCLEX, if the question asks what sign appears first in magnesium toxicity, the answer is loss of patellar reflexes (at 7–10 mEq/L). Respiratory depression follows at 10–13 mEq/L. Cardiac arrest occurs at >15 mEq/L. The antidote is calcium gluconate 1 g IV — it must be at the bedside before the infusion starts.

2. BP ≥160/110 sustained = medical urgency requiring treatment within 30–60 minutes. NCLEX tests whether you know that waiting is not acceptable. Antihypertensive treatment must begin promptly to prevent maternal stroke and abruption.

3. HELLP triad with specific lab thresholds. Memorize: LDH >600 (hemolysis), AST/ALT >70 (liver enzymes), platelets <100,000. NCLEX frequently uses an SATA or priority question that requires you to distinguish HELLP from routine preeclampsia based on the lab values.

4. Eclampsia can occur without proteinuria. Since ACOG 2013, proteinuria is not required for either preeclampsia or eclampsia. A patient who seizes after 20 weeks of pregnancy without prior proteinuria may still have eclampsia. Do not let the absence of proteinuria rule out the diagnosis.

5. Magnesium sulfate is not an antihypertensive — its purpose is seizure prophylaxis. This is one of the most common NCLEX distractors in preeclampsia questions. Magnesium treats the CNS, not the BP. Labetalol, hydralazine, and nifedipine are the antihypertensive agents.

6. Postpartum eclampsia risk peaks in the first 48 hours but extends to 4 weeks. If a NCLEX question presents a patient who developed a seizure 5 days after a normal delivery with no prior preeclampsia diagnosis, consider late postpartum eclampsia. Discharge teaching must include return-to-care warning signs.

7. Lateral decubitus (left side-lying) position improves uteroplacental blood flow. The gravid uterus compresses the inferior vena cava in the supine position. Left lateral positioning relieves this, improving venous return and placental perfusion. This is the standard positioning for any preeclamptic patient in labor.

8. No ACE inhibitors or ARBs in pregnancy. These drug classes cause fetal renal dysplasia, oligohydramnios, and neonatal renal failure. Captopril, lisinopril, enalapril, losartan, and valsartan are all contraindicated. If a NCLEX question gives a preeclamptic patient a medication history that includes an ACEI or ARB, the priority action is to flag the medication.

9. Oliguria threshold is <30 mL/hr. This signals worsening renal involvement and, during MgSO4 infusion, impaired magnesium clearance (raising toxicity risk). Report urine output <30 mL/hr to the provider immediately. Do not increase IV fluids without a provider order — fluid overload in preeclampsia can precipitate pulmonary edema.

Related resources

For the broader context of obstetric nursing care, the obstetric nursing reference covers the complete labor and delivery nursing framework. Preeclampsia frequently coexists with or precedes postpartum hemorrhage, and the nursing priorities in both conditions overlap significantly. For antepartum bleeding comparison, see the placenta previa and abruption nursing reference.

HELLP syndrome lab interpretation requires familiarity with normal lab ranges — the nursing lab values cheat sheet covers LDH, platelet counts, and liver function reference ranges. Because magnesium sulfate affects serum electrolyte balance, the electrolyte imbalances nursing reference provides useful context for understanding magnesium physiology and toxicity. For ectopic pregnancy nursing — another OB emergency with overlapping triage considerations — see the ectopic pregnancy nursing reference.

Sources: ACOG Practice Bulletin 222 (2020): Gestational Hypertension and Preeclampsia; Magee et al., NEJM 2022; StatPearls: Preeclampsia; CDC Maternal Mortality Surveillance, 2022; Gabbe’s Obstetrics: Normal and Problem Pregnancies, 8th ed.