Hypertensive states in pregnancy include preeclampsia-eclampsia, chronic hypertension (either essential or secondary to renal disease, endocrine disease, or other causes), chronic hypertension with superimposed preeclampsia, and gestational hypertension (Table 19-1). Preeclampsia is hypertension associated with proteinuria and edema, occurring primarily in nulliparas after the 20th gestational week and most frequently near term. Recent data support the elimination of edema as a diagnostic criterion. Eclampsia is the occurrence of seizures that cannot be attributed to other causes in a preeclamptic patient. Chronic hypertension is defined as hypertension that is present before conception, before 20 weeks' gestation or that persists for more than 6 weeks postpartum. Hypertension is defined as blood pressure equal to or greater than 140/90 mm Hg or an increase in mean arterial pressure of 20 mm Hg. The use of an increase in blood pressure of 30/15 mm Hg over first-trimester values is controversial. Recent data report no increased adverse events in women with these changes. However, an increase in blood pressure by this amount warrants close observation.
Hypertensive States of Pregnancy
L Clinical Findings
L Differential Diagnosis
L Clinical Findings
- Chronic Hypertension
L Clinical Findings
Proteinuria is defined as the excretion of 300 mg or more in a 24-hour specimen or 30 mg/dL in a random specimen. Preeclampsia may occur in women with chronic hypertension (superimposed preeclampsia); the prognosis is worse for the mother and fetus than with either condition alone. The criteria for superimposed preeclampsia are worsening hypertension (30 mm Hg systolic or 15 mm Hg diastolic above the average of values before 20 weeks' gestation) together with either nondependent edema or proteinuria.
Gestational hypertension is further divided into transient hypertension of pregnancy if preeclampsia is present at the time of delivery and the blood pressure is normal by 12 weeks postpartum, and chronic hypertension if the elevation in blood pressure persists beyond 12 weeks postpartum. This condition is often predictive of the later development of essential hypertension.
It is frequently difficult to determine whether a patient has preeclampsia, chronic hypertension, or chronic hypertension with superimposed preeclampsia. This is partly because blood pressure normally decreases during the second trimester, and the decrease may mask the presence of chronic hypertension. Renal biopsy studies have shown that only about 70% of primigravidas under 25 years of age with the triad of edema, hypertension, and proteinuria have glomeruloendotheliosis, the characteristic lesion of preeclampsia.
Twenty-five percent have unsuspected renal disease. In multiparas with chronic hypertension with superimposed preeclampsia, about 3% have glomeruloendotheliosis and 21% have underlying renal disease. Renal biopsy is rarely performed in pregnancy because the benefit usually does not justify the risk. The sensitivity and specificity of biochemical markers such as uric acid and antithrombin III are unknown.
Preeclampsia occurs in about 6% of the general population; the incidence varies with geographic location. Predisposing factors are nulliparity ...
THE IMPACT OF PREECLAMPSIA
Preeclampsia and related hypertensive disorders of pregnancy impact 5-8% of all births in the United States. Incidence rates for preeclampsia alone - in the United States, Canada and Western Europe, range from 2-5%. In the developing world, severe forms of preeclampsia and eclampsia are more common, ranging from a low of 4% of all deliveries to as high as 18% in parts of Africa. The variation in incidence rates is driven by the diversity of definitions and other criteria (including procedures, tests and their methodologies). In Latin America, preeclampsia is the #1 cause of maternal death.
Ten million women develop preeclampsia each year around the world. Worldwide about 76,000 pregnant women die each year from preeclampsia and related hypertensive disorders. And, the number of babies who die from these disorders is thought to be on the order of 500,000 per annum.
In developing countries, a woman is seven times as likely to develop preeclampsia than a woman in a developed country. From 10-25% of these cases will result in maternal death.
Preeclampsia should be detected and appropriately managed before the onset of convulsions (eclampsia) and other life-threatening complications. Administering drugs such as magnesium sulfate for pre-eclampsia can lower a woman's risk of developing eclampsia. In the U.S., pregnant women are commonly followed by a health care specialist (doctor, midwife or nurse) with frequent prenatal evaluations. In areas of the world with little access to care and lower social status of women, traditional health practices are usually inadequate to detect preeclampsia early. Hypertensive disorders of pregnancy commonly advance to more complicated stages of disease, and many births and deaths occur at home unreported.
Poor women in remote areas are the least likely to receive adequate health care. This is especially true for regions with low numbers of skilled health workers, such as sub-Saharan Africa and South Asia. Although levels of prenatal care have increased in many parts of the world during the past decade, the World Health Organization reports that only 46% of women in low-income countries benefit from skilled care during childbirth.
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