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
References:
ALARM
Integrated Blood Pressure Control 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4968992/
SOGC 2014. https://sogc.org/wp-content/uploads/2014/05/gui307CPG1405Erev.pdf