Hypertensive Disorders of Pregnancy

Definitions

Chronic (preexisting) hypertension (prior to pregnancy or onset <20w gestation)

  • sBP ≥140 or dBP ≥90 on two measurements at least four hours apart

Gestational Hypertension (onset >20w gestation)

  • sBP ≥140 or dBP ≥90 on two measurements at least four hours apart

  • No proteinuria

  • No severe features of preeclampsia

Preeclampsia

  • sBP ≥140 or dBP ≥90 on two measurements at least four hours apart, or sBP ≥160 or dBP ≥110 confirmed within shorter interval

AND

  • Proteinuria (eg. Urine PCR ≥0.3, or ≥0.3g protein in 24h urine )

OR

  • Severe features of preeclampsia

Preeclampsia on chronic hypertension

  • Sudden increase in blood pressure, or sudden increase or new onset proteinuria

OR

  • Severefeatures of preeclampsia

Eclampsia

  • Generalized seizures due to preeclampsia

HELLP syndrome

  • Hemolysis, Elevated Liver enzymes, Low Platelets

  • May have hypertension

Preeclampsia

Severe features

  • Symptoms of CNS dysfunction

    • Photopsia, scotomata, cortical blindness, retinal vasospasm

    • Severe headache (ie, incapacitating, "the worst headache I've ever had") or headache that persists and progresses despite analgesic therapy

    • Altered mental status

  • Hepatic abnormality

    • Severe RUQ or epigastric pain unresponsive to medication and no alternative diagnosis

    • Serum transaminase ≥2 x ULN

  • Severe hypertension

    • sBP ≥ 160 or dBP ≥ 110

  • Thrombocytopenia

    • Platelets <100,000 platelets/microL

  • Renal failure

    • Creat >97.2 micrmol/L or doubling of concentration (in absence of other renal disease)

  • Pulmonary edema

Risk factors

  • High risk

    • Previous preeclampsia (especially early onset with adverse outcome)

    • Multifetal gestation

    • Pre-existing medical conditions (hypertension, diabetes, renal disease)

    • Autoimmune disease (anti-phospholipid syndrome, SLE)

  • Moderate risk

    • Nulliparity

    • Obesity (BMI>30)

    • Family history of preeclampsia (mother/sister)

    • Age ≥ 35y

    • Low SES

    • African American

Prevention

  • Low risk

    • Low-dose aspirin NOT helpful

    • Calcium supplement >1g/d or increase dietary calcium

  • High risk

    • Low-dose aspirin (75-160mg daily) small decrease in risk (~10%)

      • Earlier = better (<16w)

    • High dose calcium 1-2g calcium

  • Note: If already established preeclampsia, no difference if given aspirin/Calcium

Complications

  • Maternal organ dysfunction (liver, kidney)

  • Fetal growth restriction, death

Investigations

  • Vitals (including Oxygen saturation)

  • UA (≥1+ proteinuria without RBC or casts)

    • Urine protein:creatinine ratio ≥0.3 (may consider confirming ≥0.3g protein in a 24-hour urine specimen)

  • CBC (decreased Hb/plat)

  • INR/aPTT, fibrinogen (increased INR/aPTT, decreased fibrinogen)

  • Serum creat, uric acid, glucose, AST/ALT, LDH, Bili, Alb

  • Blood type and crossmatch (if suspect will need transfusion)

  • Fetal status (NST, BPP)

    • Consider ultrasound for amniotic fluid volume and fetal weight (risk of oligohydramnios and fetal growth restriction)

Management

  • Referral to obstetrics, repeat investigations and fetal monitoring

Acute >160/110

  • Antihypertensive goal <160/110 for strokes (does not help with eclampsia)

  • First line: Nifedipine 5-10mg PO q30 mins for response or Labetalol 20-40mg IV q30mins (max 220mg/day)

    • Second line: Hydralazine 5mg IV q30mins (max 20mg/day)

  • Consider inpatient admission

Maintenance

  • Target BP <140/90

  • First line oral labetalol, oral methyldopa, Nifedipine PA or XL

    • Note: ACE-i/ARB and atenolol are contraindicated (IUGR, prematurity, oligohydramnios, anomalies)

Careful With Fluids

  • Monitor O2

    • Beware of pulmonary edema

  • Assess volume status, consider small bolus (500mL NS)

    • Urine output <15mL/h tolerated for few hours

  • Monitor Creatinine

Seizure Prophylaxis

  • Primary prevention

    • Severe preeclampsia, non-severe preeclampsia with symptoms, HELLP

      • If requires seizure prophylaxis, treat MgSO4 4g IV during labour and first 24h

  • Secondary prevention of recurrent seizures in eclampsia

  • Monitor for magnesium toxicity

    • Loss of reflexes, respiration >12/min, LOC, urine output >100mL/4h

      • If toxic consider 10mL of 10% calcium gluconate IV

Eclampsia

  • Call for help

  • Turn woman to side

  • Protect airway

  • Start MgSO4 4g IV over 30 mins then maintenance

  • Administer oxygen when seizures stops, take vitals

  • Assess for placental abruption, DVT, CVA, cardiomyopathy

Delivery

  • Pre-existing HTN without complications - 38w

  • Gestational HTN without complications - 37w

  • Preeclampsia without severe complications - 37w

  • Preeclampsia with severe features - deliver regardless of age

HELLP

  • Hemolysis, Elevated Liver enzymes (AST, ALT, LDH), Low Platelets

  • Consider BP control and MgSO4 as above

    • If platelets <50, consider corticosteroids

      • Increases platelets

    • If platelets <50, falling or coagulopathy consider transfusion

    • If platelets <20, transfuse prior to C/S or vaginal delivery

Postpartum

  • HTN and complications may worsen during first few postpartum days

  • Consider furosemide to postpartum medication

  • Monitor until improving, BP<160/100 for 24h