Hypertension is the most common medical problem encountered during pregnancy, complicating 2-3% of pregnancies. Hypertensive disorders during pregnancy are classified into 4 categories, as recommended by the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy[1] :
Chronic hypertension
Preeclampsia-eclampsia
Preeclampsia superimposed on chronic hypertension
Gestational hypertension (transient hypertension of pregnancy or chronic hypertension identified in the latter half of pregnancy). [1] This terminology is preferred over the older but widely used term "pregnancy-induced hypertension" (PIH) because it is more precise.
In 2008, the Society of Obstetricians and Gynecologists of Canada (SOGC) released revised guidelines that simplified the classification of hypertension in pregnancy into 2 categories, preexisting or gestational, with the option to add "with preeclampsia" to either category if additional maternal or fetal symptoms, signs, or test results support this.[2]
In 2015, the American College of Obstetricians and Gynecologists Committee on Obstetric Practice issued updated guidelines regarding the emergency treatment of acute onset severe hypertension during pregnancy, including the following[3, 4] :
Acute-onset, severe hypertension that is accurately measured using standard techniques and is persistent for 15 minutes or longer is considered a hypertensive emergency.
Intravenous (IV) labetalol and hydralazine have long been considered first-line medications for the management of acute-onset, severe hypertension in pregnant women and women in the postpartum period. Available evidence suggests that oral nifedipine also may be considered as a first-line therapy.
Parenteral labetalol should be avoided in women with asthma, heart disease, or congestive heart failure.
When urgent treatment is needed before the establishment of IV access, the oral nifedipine algorithm can be initiated as IV access is being obtained, or a 200-mg dose of labetalol can be administered orally. The latter can be repeated in 30 minutes if appropriate improvement is not observed.
Magnesium sulfate is not recommended as an antihypertensive agent, but magnesium sulfate remains the drug of choice for seizure prophylaxis in severe preeclampsia and for controlling seizures in eclampsia.
Sodium nitroprusside should be reserved for extreme emergencies and used for the shortest amount of time possible because of concerns about cyanide and thiocyanate toxicity in the mother and fetus or newborn, and increased intracranial pressure with potential worsening of cerebral edema in the mother.
There is a need for adoption of standardized, evidence-based clinical guidelines for managing patients with preeclampsia. Individuals and institutions should have mechanisms in place to initiate the prompt administration of medication when a patient presents with a hypertensive emergency.
Definitions
Chronic hypertension is defined as blood pressure exceeding 140/90 mm Hg before pregnancy or before 20 weeks' gestation. When hypertension is first identified during a woman's pregnancy and she is at less than 20 weeks' gestation, blood pressure elevations usually represent chronic hypertension.
In contrast, new onset of elevated blood pressure readings after 20 weeks' gestation mandates the consideration and exclusion of preeclampsia. Preeclampsia occurs in up to 5% of all pregnancies, in 10% of first pregnancies, and in 20-25% of women with a history of chronic hypertension. Hypertensive disorders in pregnancy may cause maternal and fetal morbidity, and they remain a leading source of maternal mortality.
The following is a computed tomography (CT) image of the brain in woman who suffered an eclamptic seizure.