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Chapter 5: Hypertensive Emergencies

Baha M. Sibai

INTRODUCTION

Hypertensive disorders are the most common medical complications of pregnancy, which affect 5% to 10% of all pregnancies.1 Approximately 30% of hypertensive disorders in pregnancy are due to chronic hypertension and 70% are due to gestational hypertension—preeclampsia. The spectrum of the disease ranges from mildly elevated blood pressures with minimal clinical significance to severe hypertension and multiorgan dysfunction. Understanding the disease process and its impact on pregnancy is of utmost importance, as hypertensive disorders remain a major cause of maternal and perinatal morbidity and mortality worldwide (Table 5-1).

TABLE 5-1Adverse Outcomes in Severe Hypertensive Disorders of Pregnancy
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TABLE 5-1 Adverse Outcomes in Severe Hypertensive Disorders of Pregnancy

Maternal complications

  • Abruption placentae

  • Disseminated intravascular coagulopathy

  • Eclampsia

  • Renal failure/need for dialysis

  • Liver hemorrhage or failure

  • Intracerebral hemorrhage

  • Hypertensive encephalopathy

  • Pulmonary edema/adult respiratory distress syndrome

  • Death

Fetal-neonatal complications

  • Severe intrauterine growth restriction

  • Oligohydramnios

  • Preterm delivery

  • Hypoxia-acidosis

  • Neurologic injury

  • Death

DEFINITIONS AND CLASSIFICATIONS

Hypertension is defined as a systolic blood pressure greater than or equal to 140 mm Hg or a diastolic blood pressure greater than or equal to 90 mm Hg. These measurements must be made on at least two occasions, no less than 4 hours and no more than a week apart. It is important to note that choosing the appropriate blood pressure cuff size will help to eliminate inaccurate blood pressure measurements.1 Abnormal proteinuria in pregnancy is defined as the excretion of greater than or equal to 300 mg of protein in 24 hours, a protein:creatinine ratio of greater than or equal to 0.30, or a urine dipstick of at least 1+ on occasions. The most accurate measurement of total urinary excretion of protein is with the use of a 24-hour urine collection. However, in certain instances the use of semiquantitative dipstick analysis may be the only measurement available to assess urinary protein. Table 5-2 lists the classification of hypertension.1

TABLE 5-2Classification of Hypertension
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TABLE 5-2 Classification of Hypertension

I. Gestational hypertension: new onset hypertension at >20 weeks

  • Systolic 140 to <160 mm Hg or

  • Diastolic 90 to <110 mm Hg

  • Absent symptoms consistent with preeclampsia

  • Normal laboratory tests

II. Gestational proteinuria ≥300 mg/24 h or Protein/creatinine ratio 0.30 or ≥1 + on dipstick

III. Preeclampsia (hypertension ± proteinuria)

Preeclampsia with severe features: gestational hypertension/preeclampsia plus (any of the following):

  • Severe hypertension: Systolic ≥160 mm Hg or diastolic ≥110 mm Hg on at least 4 hours apart or once if treated with IV antihypertensive medications

  • Persistently severe cerebral symptoms: new onset headaches or visual changes

  • Persistent severe epigastric pain not responding to medications

  • Thrombocytopenia <100,000/mm3

  • Elevated liver enzymes >2 × upper limit normal for local laboratory

  • Pulmonary edema

  • Serum creatinine >1.1 mg/dL

IV. Chronic hypertension

Hypertension before pregnancy

Hypertension before 20 weeks ...

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