Obstetrics and Gynecology/Hypertensive Disorders including Pre-Eclampsia

Gestational Hypertension

Definition

• Diastolic blood pressure greater than 90mmHg on two recordings on the same arm greater than five minutes apart.
• Gestational hypertension must be new onset after the 20th week of gestation.

Epidemiology

• Affects 5% of pregnancies.
• Along with bleeding, the leading cause of maternal mortality in Canada.
• 35% risk of developing preeclampsia

Preexisting Hypertension

Definition

• Hypertension in pregnant women diagnosed prior to the 20th week of gestation.

Epidemiology

• 25% risk of developing preeclampsia, with a 25% recurrence.

Pre-Eclampsia

Definition

• Gestational hypertension with proteinuria or end organ dysfunction.
• Preexisting hypertension with resistant hypertension with new or worsening proteinuria or one or more adverse conditions.
  • Resistant hypertension requires 3 or more drugs for control after 20 weeks of gestation.
  • Proteinuria is suspected at a urine dipstick result >2. If this result is positive, a 24h protein collection should be done and the result will be >300mg/day. The latter test is performed to account for orthostatic proteinuria which may confound the dipstick test.
  • Adverse conditions are defined as
    • BP >160/110
    • HELLP syndrome: Hemolysis, Elevated Liver enzymes, Low Platelets. Leads to placental abruption, hepatic and or renal dysfunction, preterm delivery, and death.
    • Proteinuria >5g per day
    • CNS symptoms
    • Pulmonary edema
    • Fetal growth restriction
• Severe preeclampsia is pre-eclampsia beginning before 34 weeks with 5g proteinuria per day. 20% of these women develop HELLP

Etiology

• Etiology unknown, but may involve vascular endothelial damage and widespread coagulation.
• Risk factors include nulliparity, >35 or <18 years of age in the mother, past history of preeclampsia or hypertension, connective tissue disease, diabetes, black, thrombophilia, antiphospholipid antibody syndrome, and mulitfetal gestation.

Pathophysiology

• The primary factor is vasospasm to separate end organs.
• Hematologic abnormalities include hemolysis, thrombocytopenia, and coaglulopathy secondary to hepatic dysfunction.
• Decreased renal blood flow leads to increased blood urea nitrate concentration.
• Neurological sequelae ensue: headache, visual changes, seizures from intracranial bleeding.
• Decreased blood flow to the fetus creates hypoxia, growth restriction, and oligohydramnios.

Clinical Presentation

• Eclampsia

Management

• The primary treatment for gestational hypertension and pre-eclampsia is delivery.
• If term gestation (>37 weeks), deliver the baby.
• If preterm (<34 weeks), only deliver if membranes have ruptured, if the fetal status is questionable, intrauterine growth retardation, and the fetal lungs appear mature.
  • Patients should be sent to a tertiary center with high-level neonatal care.
• If adverse conditions are present
  • Antihypertensive medications should be administered (target less than 160/110, but with the diastolic pressure no lower than 90 acutely)
  • MgSO4
  • Anesthesia
  • Delivery
• MgSO4 IV bolus and infusion for eclampsia, antihypertensives, and delivery. The mother is the first priority in this circumstance.
• Delivery independent of gestational age for HELLP syndrome.
• Prevention: baby aspirin once every day; calcium 1g per day, every day.

Magnesium Sulfate Toxicity
May lead to cardiac arrest
Decreased urine output
Loss of deep tendon reflexes
Respiratory insufficiency
Must be treated with 10cc of 10% Calcium Gluconate STAT