Hypertensive disorders occur in approximately 12% H to 22% of pregnancies and cause substantial peri-natal morbidity and mortality for both mother and fetus. Hypertensive disease is directly responsible for ap-proximately 20% of maternal deaths in the United States. The exact cause of hypertension in pregnancy remains unknown.
Various classifications of hypertensive disorders in preg-nancy have been proposed. Box 16.1 presents a commonly used classification. Because hypertensive disorders in preg-nancy represent a spectrum of disease, classification systems should be used as a guide only
Chronic hypertension is defined as hypertension present beforethe 20th week of pregnancy or hypertension present before preg-nancy. The categories of hypertension in pregnancy andthe blood pressure (BP) criteria used to define each are as follows:
· Mild hypertension: Systolic pressure of >=140–180 mm Hg or diastolic pressure of >=90–100 mm Hg or both
· Severe hypertension: Systolic pressure of >=180 mm Hg or diastolic pressure of >=100 mm Hg
A major risk with chronic hypertension is the development of preeclampsia or eclampsia later in the pregnancy, which is relatively common and difficult to diagnose. The acute onset of proteinuria and worsening hypertension in women with chronic hypertension is suggestive of superimposed preeclampsia.
Preeclampsia is the development of hypertension with protein-uria and edema after 20 weeks of gestation. This condition canoccur earlier in the presence of gestational trophoblastic disease. Risk factors for preeclampsia are in Box 16.2. The criteria for diagnosis of preeclampsia are:
· Blood pressure of >=140 mm Hg systolic or >=90 mm Hg diastolic that occurs after 20 weeks of gestation in a woman with previously normal blood pressure
· Proteinuria, defined as urinary excretion of 0.3 g protein or higher in a 24-hour urine specimen
Severe preeclampsia is characterized by one or more ofthe following:
· Blood pressure >=160 mm Hg systolic or >=110 mm Hg diastolic on two occasions at least 6 hours apart while the patient is on bed res
· Marked proteinuria (generally >=5 g per 24-hour urine collection, or 3+ or more on two dipstick of random urine samples collected at least 4 hours apart)
· Oliguria <500 mL in 24 hours
· Cerebral or visual disturbances such as headache and scotomata (“spots” before the eyes)
· Pulmonary edema or cyanosis
· Epigastric or right-upper-quadrant pain (probably caused by subcapsular hepatic hemorrhage or stretching of Glisson capsule)
· Evidence of hepatic dysfunction
· Intrauterine fetal growth restriction (IUGR)
These changes illustrate the multisystem involvement asso-ciated with preeclampsia. Severe preeclampsia is an indica-tion for delivery, regardless of gestational age or maturity.
Eclampsia is the additional presence of convulsions (grand mal seizures) in a woman with preeclampsia that is not explained by a neurologic disorder. Eclampsia occurs in 0.5% to 4%of patients with preeclampsia.
Most cases of eclampsia occur within 24 hours of delivery, but approximately 3% of cases are diagnosed between 2 and 10 days postpartum.
HELLP syndrome is the presence of hemolysis, elevated liverenzymes, and low platelet count.
HELLP syndrome, like severe preeclampsia, is an indication for delivery to avoid jeopardizing the health of the woman.
This syndrome is now appreciated as a distinct clinical en-tity, occurring in 4% to 12% of patients with severe pre-eclampsia or eclampsia. Criteria for diagnosis are:
· Microangiopathic hemolysis
· Hepatocellular dysfunction