V. ANATOMY AND PHYSIOLOGY

These are the organs affected by preeclampsia:

VI. PATHOPHYSIOLOGY

Preeclampsia is a characterized, by vasospasms, changes in the coagulation system,

and disturbances in systems related to volume and BP control. Vasospasms results

from an increased sensitivity to circulating pressors, such as angiotensin II, and possibly

an imbalance between the prostaglandins prostacyclin and thromboxane A1.

Endothelial cell dysfunction, believed to result from decreased placental perfusion, may

account for many changes in preeclampsia. Arteriolar vasospasm may cause

endothelial damage and contribute to an increased capillary permeability. This increase

edema and further decreases intravascular volume, predisposing the woman with

preeclampsia to pulmonary edema.

Immunologic factors may play an important role in the development of preeclampsia.

The presence of a foreign protein, the placenta, or the fetus maybe perceived by the

mother’s immune system as an antigen. This may then trigger an abnormal

immunologic response. This theory is supported by the increased incidence of

preeclampsia or eclampsia in first-time mothers or to multiparous woman pregnant by a

new partner. Preeclampsia maybe an immune complex disease in which the maternal

antibody system is overwhelmed from excessive fetal antigens in the maternal

circulation. This theory seems compatible with the high incidence of preeclampsia

among women exposed to a large mass of trophoblastic tissue as seen in twin

pregnancies or hydatidiform moles.

Genetic predisposition may be another immunologic factor. Dekker reported a greater

frequency of preeclampsia and eclampsia among daughters and granddaughters of

women with a history of eclampsia, which suggests an autosomal recessive gene

controlling the maternal immune response. Paternal factors are also examined.

Diets in inadequate nutrients, especially protein, calcium, sodium, magnesium, and

vitamin E and C, maybe an etiologic factor in preeclampsia. Some practitioners

prescribed high-protein diets (90 mg supplemental protein) without caloric restriction

and moderate sodium intake in the prevention and treatment of this disorder. However,

data are limited regarding the association between diet and preeclampsia.

Preeclampsia progresses along a continuum from mild disease to severe

preeclampsia, HELLP syndrome, or eclampsia. The pathophysiology of preeclampsia

reflects alteration in the normal adaptations of pregnancy. Normal physiologic

adaptations to pregnancy include increase blood plasma volume, vasodilation, and

decreased systemic vascular resistance, elevated cardiac output, and decreased colloid

osmotic pressure. Pathologic changes in the endothelial cells of the glomeruli are

uniquely characteristic of preeclampsia, particularly in nulliparous women. The main

pathogenic factor is not an increase in BP but poor perfusion as a result vasospasm.

Arteriolar vasospasm diminishes the diameter of blood vessels, which impedes blood

flow to all organs and raises BP. Function in organs such as the placenta, kidneys, liver

and brain is deceased by as much as 40% to 60%.