Everything You Need to Know About Preeclampsia/eclampsia for Step 1

Preeclampsia/eclampsia is one of those OB topics that shows up everywhere on Step 1 and Step 2: vignettes, pharm questions, ethics “what’s the next step?”, and postpartum complications. If you can connect abnormal placentation → endothelial dysfunction → vasospasm + leaky capillaries + end-organ injury, most questions become predictable.

---

The Core Definitions (Know These Cold)

Preeclampsia

New-onset hypertension after 20 weeks gestation plus either:

• Proteinuria or
• End-organ dysfunction (even without proteinuria)

Hypertension criteria

• $\ge 140/90$ on 2 readings at least 4 hours apart, after 20 weeks, in a previously normotensive patient
• Severe-range: $\ge 160/110$

Proteinuria criteria (any one)

• $\ge 300$ mg/24 hours
• Protein/creatinine ratio $\ge 0.3$
• Dipstick $\ge 2+$ (less preferred)

Eclampsia

Preeclampsia + seizures (generalized tonic-clonic) not attributable to another cause.

HELLP Syndrome (a severe variant)

• Hemolysis (often microangiopathic hemolytic anemia)
• Elevated Liver enzymes
• Low Platelets

💡

First Aid tie-in: Preeclampsia/eclampsia and HELLP appear in the pregnancy HTN disorders section (OB/GYN + pathology + pharm overlaps). This is a classic “vascular/endothelial injury” concept.

---

Pathophysiology: The Story You Should Tell Yourself

Step 1-level mechanism: abnormal placentation

In normal pregnancy, trophoblasts remodel maternal spiral arteries into high-capacitance, low-resistance vessels.

In preeclampsia, trophoblastic invasion is shallow/incomplete → spiral arteries stay narrow, high-resistance → placental ischemia.

What does the ischemic placenta do?

It releases anti-angiogenic and inflammatory factors (classically tested concept):

• ↑ sFlt-1 (soluble Fms-like tyrosine kinase-1) binds and reduces free VEGF and PlGF
• ↓ angiogenesis → endothelial dysfunction

The consequences of endothelial dysfunction

Think: vasospasm + increased vascular permeability + activation of coagulation

• Hypertension (vasoconstriction)
• Proteinuria (glomerular endothelial injury)
• Edema (capillary leak; can be pulmonary)
• End-organ ischemia (brain, liver, kidney, placenta)

Kidney pathology you should recognize

Glomerular endotheliosis = swelling of glomerular endothelial cells with narrowed capillary lumens → ↓ GFR and proteinuria.

---

Risk Factors (High-Yield Associations)

Preeclampsia is more likely when there’s more placental tissue or less maternal immune tolerance to placental antigens:

Classic risk factors

• Nulliparity (first pregnancy)
• History of preeclampsia (strong risk for recurrence)
• Multifetal gestation (more placenta)
• Molar pregnancy (abnormal trophoblast, lots of placental tissue)
• Chronic hypertension
• Diabetes mellitus
• CKD
• Autoimmune disease (esp. antiphospholipid syndrome, SLE)
• Obesity, advanced maternal age

Step-friendly memory hook: “First placenta exposure, more placenta, or maternal vascular disease”.

---

Clinical Presentation: How It Shows Up in Vignettes

Common findings

• HTN after 20 weeks
• Proteinuria
• Edema (not required for diagnosis, but commonly present)

Severe features (these convert “preeclampsia” → “preeclampsia with severe features”)

Any of the following can qualify, even without massive proteinuria:

• Severe BP: $\ge 160/110$
• Thrombocytopenia: platelets < 100,000
• Renal insufficiency: creatinine > 1.1 mg/dL or doubling baseline
• Impaired liver function: elevated AST/ALT, RUQ/epigastric pain
• Pulmonary edema
• New-onset cerebral/visual symptoms: headache, scotomata, hyperreflexia, altered mental status

Eclampsia clues

• Severe headache, visual changes, hyperreflexia/clonus → then seizure
• Can occur antepartum, intrapartum, or postpartum (postpartum eclampsia is a classic trap)

---

Diagnosis: What the Question Actually Wants

Step-style diagnostic checklist

1. Confirm timing: after 20 weeks
2. Confirm BP
3. Look for proteinuria OR end-organ dysfunction
4. Decide if severe features are present

Key labs to order/interpret

💡

High-yield vignette: “Pregnant at 32 weeks with HTN, RUQ pain, elevated AST/ALT, low platelets” → HELLP.

---

Management: The Boards-First Approach

The only definitive treatment

Delivery of the placenta (i.e., delivery of the fetus and placenta).

But the timing depends on gestational age and severity.

---

Treatment Algorithms (What to Do and When)

Preeclampsia without severe features

• If ≥ 37 weeks → deliver
• If < 37 weeks → expectant management + close monitoring (maternal labs, BP, fetal status)

Preeclampsia with severe features

• If ≥ 34 weeks → deliver
• If < 34 weeks → stabilize mom, consider corticosteroids for fetal lung maturity if time allows, then proceed based on maternal/fetal status (many will still require delivery)

Eclampsia (seizure = emergency)

1. Magnesium sulfate for seizure treatment and prophylaxis (first-line)
2. Stabilize (ABCs)
3. Control severe BP
4. Delivery once stabilized (do not delay for prolonged “expectant management”)

---

Medications You Must Know (Step 1 Pharm + Step 2 OB)

Magnesium sulfate

Use: seizure prophylaxis/treatment in severe preeclampsia and eclampsia

Toxicity signs (classic Step question)

• Loss of deep tendon reflexes
• Respiratory depression
• Cardiac arrhythmias

Antidote: Calcium gluconate

Antihypertensives used in pregnancy (acute severe HTN)

Common board answers:

• IV labetalol
• IV hydralazine
• Oral nifedipine

Drugs to avoid in pregnancy HTN

• ACE inhibitors/ARBs (fetal renal dysgenesis, oligohydramnios, skull hypoplasia)
• Aliskiren (similar pathway concerns)

💡

First Aid cross-reference idea: This topic integrates with FA’s antihypertensive pharm section (pregnancy contraindications) and reproductive pathology.

---

Complications (Maternal + Fetal)

Maternal complications

• Eclampsia (seizures)
• Stroke/intracranial hemorrhage (from severe HTN)
• Pulmonary edema
• Acute kidney injury
• HELLP
• DIC
• Placental abruption (painful bleeding + uterine tenderness)

Fetal complications

• IUGR (uteroplacental insufficiency)
• Oligohydramnios
• Preterm delivery
• Fetal hypoxia/distress
• Stillbirth (severe cases)

---

HELLP Syndrome: Extra High-Yield Mini-Section

How it presents

• RUQ/epigastric pain, nausea/vomiting, malaise
• HTN/proteinuria may be present but not always dramatic
• Labs: hemolysis + elevated LFTs + low platelets

Management (boards)

• Stabilize + deliver (especially if maternal instability)
• Magnesium sulfate (seizure prophylaxis)
• Blood products as needed (platelets if significant thrombocytopenia with bleeding/procedures)

---

Differentials You’ll Be Asked to Separate

Preeclampsia vs gestational hypertension

• Gestational HTN: HTN after 20 weeks without proteinuria or end-organ findings
• Preeclampsia: HTN after 20 weeks with proteinuria or end-organ dysfunction

Preeclampsia vs chronic HTN

• Chronic HTN: HTN before pregnancy or before 20 weeks
• Superimposed preeclampsia: chronic HTN + new proteinuria or end-organ dysfunction after 20 weeks

Eclampsia vs epilepsy

• Eclampsia often preceded by headache/visual symptoms/hyperreflexia, occurs around pregnancy/postpartum in a preeclampsia context.
• If vignette includes severe HTN + proteinuria + seizure → assume eclampsia unless proven otherwise.

---

High-Yield “Exam Triggers” (Quick Hits)

• After 20 weeks + HTN + proteinuria → preeclampsia until proven otherwise.
• Seizure in a pregnant/postpartum patient → treat as eclampsia and give MgSO₄.
• Mg toxicity → loss of reflexes is an early warning; antidote calcium gluconate.
• RUQ pain + low platelets + high AST/ALT → HELLP, think urgent management.
• Molar pregnancy/multifetal gestation → increased risk (more trophoblastic tissue).
• Definitive treatment is delivery—everything else is stabilization/bridging.

---

Rapid Review Table (Great for Last-Minute Passes)