When the vessels vasospasm, they constrict, which results in increased blood pressures. This causes hypertension and decreased perfusion into the tissues. This subsequent decrease in perfusion results in kidney, liver, and brain damage.
As a result of the increased pressures and liver dysfunction, the red blood cells become hemolyzed and platelets adhere to tissue walls. If the intravascular coagulation issues persist, the pregnant woman will have a low platelet count and may develop disseminated intravascular coagulation (DIC).
As pressure increases, damage occurs allowing for capillary leakage to occur. As the capillaries leak, proteinuria, generalized edema, and pulmonary edema develop.
Hypertension occurs when the uterine vessels are unable to adequately expand to account for the increased blood flow that occurs during pregnancy. This causes the vessels to vasospasm, or clamp down, resulting in increased pressures and decreased tissue perfusion. A BP of 160/110 or greater on two separate occasions, 6 hours apart, while the pregnant woman is on bedrest is characteristic of severe preeclampsia.
Proteinuria occurs in preeclampsia due to the capillaries leaking protein into the urine. This occurs as a result of the increased pressure, and poor renal perfusion, causing damage to the tissues. A qualitative dipstick of 3+ or greater, or a 24 hour urinalysis of proteinuria of 5 grams or greater is considered characteristic of severe preeclampsia. Besides renal damage, patients can also develop other end-organ damage, which can manifest as headache, vision abnormality, altered mental status, blindness, dyspnea with pulmonary edema, or cardiac dysfunction.
Hepatic dysfunction occurs in severe preeclampsia due to hypertension and decreased organ perfusion. As red blood cells travel through the narrowed vessels, they become damaged, causing hemolysis.
Damage occurs to the liver when blood flow is decreased. Elevated liver enzymes signify damage to the liver and progression of severe preeclampsia.
Low platelet counts occur for multiple reasons. First, as damage occurs, the platelets are used up as they adhere to the vessel wall. Secondly, the liver is responsible for the development of vital clotting factors. As liver function decreases, platelet levels will also decrease in preeclampsia.
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