How preeclampsia is tested on Step 1

Start with the placenta.

PlacentationSpiral arteries stay narrow and muscularIschemiaPlacenta becomes hypoxic; fibrinoid necrosis ofvesselsSignalssFlt-1 rises and PlGF falls → endothelial injuryOrgansHypertension, proteinuria, liver injury, cerebraledemaFetusGrowth restriction, oligohydramnios
Preeclampsia. Risk factors include first pregnancy, prior preeclampsia, chronic hypertension, diabetes, kidney disease, multiple gestation, obesity, and antiphospholipid syndrome.

Diagnosis and severe features

Classify by blood pressure, timing, and organ involvement.

ConditionDefinition
Chronic hypertensionHypertension before pregnancy or before 20 weeks
Gestational hypertensionNew hypertension after 20 weeks without proteinuria or organ damage
PreeclampsiaNew hypertension after 20 weeks + proteinuria or end-organ signs
Severe featuresBP ≥ 160/110, platelets < 100,000, liver enzymes ×2, creatinine > 1.1 mg/dL or doubled, pulmonary edema, headache, vision changes
HELLP syndromeHemolysis (schistocytes, high LDH), elevated liver enzymes, low platelets
EclampsiaNew seizures in a patient with preeclampsia

Preeclampsia can first appear after delivery (postpartum preeclampsia).

Treatment

Protect the brain, control pressure, and plan delivery.

  • Magnesium sulfate: prevents and treats eclamptic seizures. Toxicity causes loss of deep tendon reflexes, then respiratory depression and cardiac arrest; treat with calcium gluconate. It is cleared by the kidneys.
  • Antihypertensives: labetalol, hydralazine, or nifedipine for severe-range pressure. ACE inhibitors and ARBs are contraindicated in pregnancy (fetal kidney damage).
  • Delivery: at 37 weeks without severe features, or sooner (after stabilization) with severe features; corticosteroids for fetal lung maturity if preterm.

Third-trimester bleeding

Pain is the key difference.

Placental abruptionPlacenta separates earlyPainful bleeding, tender firm uterusHypertension, cocaine, trauma, smokingCan cause DIC and fetal distressBleeding may be concealedPlacenta previaPlacenta over the cervical osPainless bright red bleedingPrior cesarean, multiparity, smokingDiagnose by ultrasoundNo digital cervical examvs
Abruption vs previa. Vasa previa (fetal vessels over the os) causes painless bleeding with fetal bradycardia when membranes rupture.

Worked example

Identify severe features and treat.

functions Worked example — headache at 34 weeks

At 34 weeks, a patient has a severe headache and blurred vision. BP is 168/112 on repeat, urine protein is 3+, and platelets are 95,000/µL. What is the diagnosis and the immediate management?

  1. New hypertension after 20 weeks with proteinuria is preeclampsia.
  2. BP ≥ 160/110, headache, visual change, and platelets below 100,000 are severe features.
  3. Give magnesium sulfate to prevent seizures and an IV antihypertensive such as labetalol.
  4. Stabilize, give corticosteroids for fetal lungs if time permits, and plan delivery.

Answer. Preeclampsia with severe features: magnesium sulfate, labetalol (or hydralazine), and delivery after stabilization.