Hypertensive Disorders of Pregnancy

Introduction

Hypertensive disorders of pregnancy are a significant cause of maternal and fetal morbidity and mortality in Canada. This comprehensive guide is designed to help Canadian medical students prepare for the MCCQE1 exam, focusing on the key aspects of hypertensive disorders in pregnancy within the Canadian healthcare context.

Classification of Hypertensive Disorders in Pregnancy

Understanding the classification is crucial for MCCQE1 success. The Society of Obstetricians and Gynaecologists of Canada (SOGC) recognizes the following categories:

1. Pre-existing hypertension
2. Gestational hypertension
3. Preeclampsia
4. Other hypertensive effects

Canadian Epidemiology

In Canada, hypertensive disorders complicate about 7% of pregnancies. Understanding the Canadian context is essential for the MCCQE1:

• Preeclampsia affects 2-3% of pregnancies in Canada
• Gestational hypertension occurs in about 6% of pregnancies
• Pre-existing hypertension complicates 1-2% of pregnancies

Risk Factors

Identifying risk factors is a key competency tested in the MCCQE1. Canadian-specific risk factors include:

• First Nations, Inuit, and Métis ethnicity
• Maternal age >35 or <18 years
• Obesity (BMI >30 kg/m²)
• Pre-existing medical conditions (e.g., diabetes, renal disease)
• Multiple gestation
• Previous history of preeclampsia

Diagnosis

Accurate diagnosis is crucial for management. The SOGC defines hypertension in pregnancy as:

• Systolic blood pressure ≥140 mmHg and/or
• Diastolic blood pressure ≥90 mmHg

Measurements should be taken at least 15 minutes apart, using an appropriately sized cuff.

Proteinuria

Proteinuria is defined as:

• ≥0.3 g/day in a 24-hour urine collection, or
• Spot urine protein/creatinine ratio ≥30 mg/mmol

Management

Management strategies vary based on the specific disorder and severity. Here's a general approach:

Canadian Guidelines for Management

The SOGC provides specific guidelines for managing hypertensive disorders in pregnancy. Key points include:

1. Target BP: 130-155/80-105 mmHg for most hypertensive pregnant women
2. Magnesium sulfate for seizure prophylaxis in severe preeclampsia
3. Antenatal corticosteroids for fetal lung maturity if delivery is anticipated before 34 weeks

Complications

Understanding potential complications is crucial for the MCCQE1:

• Maternal: HELLP syndrome, eclampsia, placental abruption, DIC
• Fetal: Intrauterine growth restriction, preterm birth, stillbirth

HELLP Syndrome Mnemonic

Remember the components of HELLP syndrome with this Canadian-themed mnemonic:

• Hemolysis (Hockey)
• Elevated Liver enzymes (Edmonton)
• Low Platelets (Labrador Pup)

Key Points to Remember for MCCQE1

1. Preeclampsia can occur without proteinuria if other end-organ dysfunction is present
2. BP ≥160/110 mmHg requires urgent treatment
3. Magnesium sulfate is the drug of choice for eclampsia prevention and treatment
4. HELLP syndrome can occur without hypertension or proteinuria
5. Delivery is the definitive treatment for preeclampsia
6. Postpartum hypertension can occur up to 6 weeks after delivery

Sample Question

# Sample Question

A 28-year-old primigravida at 32 weeks gestation presents to the emergency department with a blood pressure of 162/105 mmHg and 2+ proteinuria on dipstick. She complains of a severe headache and right upper quadrant pain. Which of the following is the most appropriate next step in management?

- [ ] A. Start oral labetalol and admit for observation
- [ ] B. Administer betamethasone and plan for delivery in 48 hours
- [ ] C. Begin magnesium sulfate and prepare for immediate delivery
- [ ] D. Perform an ultrasound to assess fetal growth
- [ ] E. Order complete blood count and liver function tests

Explanation

The correct answer is:

• C. Begin magnesium sulfate and prepare for immediate delivery

This patient presents with severe preeclampsia (BP ≥160/105 mmHg, proteinuria, headache, and right upper quadrant pain suggesting liver involvement). In severe preeclampsia at 32 weeks gestation with concerning symptoms, immediate delivery is indicated after stabilization. Magnesium sulfate should be started for seizure prophylaxis.

Option A is incorrect as this case requires more urgent management. Option B is inappropriate as immediate delivery is necessary. While options D and E provide useful information, they should not delay the primary management of stabilization and delivery.

Canadian Guidelines

The SOGC recommends:

1. Urgent antihypertensive treatment for severe hypertension (≥160/110 mmHg)
2. Magnesium sulfate for severe preeclampsia
3. Delivery for severe preeclampsia remote from term
4. Antenatal corticosteroids for pregnancies <34 weeks if time permits

References

1. Magee, L. A., et al. (2014). Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy: executive summary. Journal of Obstetrics and Gynaecology Canada, 36(5), 416-441.

2. Society of Obstetricians and Gynaecologists of Canada. (2018). Hypertensive Disorders of Pregnancy. Clinical Practice Guideline No. 307.

3. Canadian Hypertensive Disorders of Pregnancy Working Group. (2012). Diagnosis, Evaluation, and Management of the Hypertensive Disorders of Pregnancy: Executive Summary. Journal of Obstetrics and Gynaecology Canada, 34(3), 416-438.

4. Butalia, S., et al. (2018). Hypertension Canada's 2018 Guidelines for the Management of Hypertension in Pregnancy. Canadian Journal of Cardiology, 34(5), 526-531.

5. Public Health Agency of Canada. (2018). Perinatal Health Indicators for Canada 2017. Ottawa: Public Health Agency of Canada.