14. Obstetrics

Pre-eclampsia/Eclampsia

Definition

Pre-eclampsia: a multisystem, pregnancy-specific condition that classically is defined as new-onset hypertension in pregnancy without a history of chronic hypertension with proteinuria and most commonly appears after 32 weeks of gestation.

Blood pressure ≥140/ 90 on two occasions 6 hours apart

300 mg protein in a 24-hour urine sample

Severe pre-eclampsia: the presence of one of the following in the setting of pre-eclampsia

Blood pressure of 160 mmHg systolic or higher or 110 mmHg diastolic or higher on two occasions at least 6 hours apart while the patient is on bed rest

Proteinuria of 5 g or higher in a 24-hour urine specimen

Oliguria of less than 500 mL in 24 hours from intravascular depletion

Cerebral or visual disturbances

Pulmonary edema or cyanosis

Epigastric or right upper-quadrant pain

Impaired liver function

Thrombocytopenia

Fetal growth restriction

Eclampsia: severe pre-eclampsia with seizures

“Classic Triad” of Pre-eclampsia: hypertension, proteinuria, peripheral edema

Epidemiology

Occurs in 5% to 8% of pregnancies with higher rates depending on the woman’s risk factors

A leading cause of maternal and fetal morbidity and mortality worldwide and in the United States

Can lead to maternal cerebrovascular accident, hypertensive urgency, eclampsia, disseminated intravascular coagulation (DIC) and typically non-permanent renal insufficiency, transaminitis, and cerebral edema

Eclampsia can result in significant maternal morbidity, often from intracranial hemorrhage.

Can lead to need for iatrogenic preterm delivery for maternal or fetal well-being, placental abruption, fetal growth restriction from placental insufficiency and stillbirth

Risk Factors

Nulliparity

History of pre-eclampsia, particularly preterm pre-eclampsia

Extremes of age (>40 years old or <20 years old)

Diabetes

Obesity

Multiple gestations

Chronic hypertension

Lupus

Kidney disease

Differential Diagnosis

Drug-induced hepatotoxicity (acetaminophen)

Acute fatty liver of pregnancy

Hemolysis, elevated liver and low platelet syndrome (HELLP) syndrome

Viral hepatitis

Hypertension

Thrombotic thrombocytopenic purpura (TTP)

Pathophysiology

Unclear at this time

Hypoxic events, immunologic, angiogenic dysregulation in the placenta are all possible pathways

Management and Treatment

Limited options for the physician to control the extent of the pre-eclampsia other than delivery of the fetus and placenta

Particularly challenging for a high-risk obstetrician to balance maternal and fetal risks with extremely preterm pre-eclampsia (expectant management placing mother and fetus at risk vs neonatal risks of preterm delivery)

Delivery (consult obstetricians)

Acute condition will reverse within 24 to 48 hours

Blood pressure control

Magnesium drip to decrease risk of eclamptic seizure ×24 hours

Bolus 4 to 6 g in 100 cc NS followed by 2 g/h infusion

Aim for magnesium level between 4.8 and 8.4 mEq/L

Monitor for magnesium toxicity

Renally cleared; pregnant women have higher GFR resulting in lower creatinine levels; creatinine ≥1 mg/dL is considered abnormal

Contraindicated in patients with myasthenia gravis

Monitor urine output and creatinine clearance

Monitor deep tendon reflexes

Magnesium levels 10 to 12 mg/dL associated with loss of deep tendon reflexes

Magnesium levels >12 mg/dL associated with higher incidence of respiratory paralysis and cardiac arrest

Antidote: 1 g calcium gluconate IV push over 5 minutes

Management of Eclampsia

Stabilize patient; prevent falls with guard rails

Aspiration precautions

Administer magnesium IV (6 g loading dose in 100 cc NS and 2 g/h continuous infusion) or IM bolus (5 mg IM × 2 buttocks)

Consider differential diagnosis of seizure; consider head imaging to rule out stroke or electrolyte abnormality as etiology

Monitor for evidence of DIC and support with blood product transfusion as necessary

Management of Hypertensive Emergency:

Considered >160/110; IV labetalol and IV hydralazine are most commonly used

Avoid nitroprusside given association with fetal cyanide toxicity except as last option for blood pressure (BP) control

Help prevent maternal stroke and placental abruption

Aim for BP 140/90; avoid drastic drops in blood pressure that may result in placental and maternal hypoperfusion

Labetalol doses

20 mg IV and reassess BP in 10 minutes

40 mg IV and reassess BP in 10 minutes

80 mg IV and reassess BP in 10 minutes

Maximum dose 220 mg

Consider IV hydralazine

Hydralazine doses

5 mg IV and reassess BP in 20 minutes

10 mg IV and reassess BP in 20 minutes

20 mg IV and reassess BP in 20 minutes

40 mg IV and reassess BP in 20 minutes

Outcomes

Responsible for ~14% of maternal deaths per year

Increased risk of pre-eclampsia and eclampsia in future pregnancies

Fetuses born to pre-eclamptic mothers carry and increased risk of intrauterine growth retardation and fetal hypoxia.

HELLP Syndrome

Definition

HELLP syndrome is a syndrome characterized by

H: hemolysis (bilirubin >1.2 mg/dL)

EL: elevated liver enzymes (LDH >600 U/L and ALT or AST >70 U/L)

LP: low platelets (<150,000/mm³)

Often regarded as a form of severe pre-eclampsia that results in thrombocytopenia, transaminitis two-fold increase above normal values and hemolysis

Epidemiology

May occur in up to 20% of women with severe pre-eclampsia

A minority may present atypically without proteinuria or hypertension.

May be difficult to differentiate between Hemolytic uremic syndrome – thrombotic thrombocytopenic purpura (HUS-TTP) and acute fatty liver of pregnancy