Preeclampsia is a serious metabolic disturbance (toxemia) of pregnancy that occurs most often following the twentieth week of pregnancy. Preeclampsia involves a systemic malfunction of the tissue lining the blood vessels (vascular endothelium) and is characterized by high blood pressure (hypertension), swelling (edema), and high amounts of protein in the urine (proteinuria). It is one of a group of disorders that appear to be progressive steps in a single process that includes gestational hypertension (blood pressure of 140/90 or greater), mild and severe preeclampsia, and eclampsia. Eclampsia is a severe progression of preeclampsia characterized by one or more convulsions (seizures) not associated with epilepsy, brain hemorrhage, and coma. Most cases of eclampsia develop in the third trimester of pregnancy with seizures occurring within 2 days after delivery in 80% of cases (Ross).
The precise cause of preeclampsia is unknown. Some theories include immune system dysfunction, genetic factors, placental abnormalities or premature placental detachment from the uterine wall (abruptio placentae), and low antitoxic protective mechanisms due to low protein (albumin) levels in the blood. It is believed to start with endothelial cell injury resulting in constriction of blood vessels and a reduced blood supply (reduced vascular perfusion) in the placenta (placental hypoperfusion), although it remains unclear exactly why this occurs. Organ systems including the brain, liver, and kidneys also are affected. The process may begin without symptoms and become apparent only after hypertension has developed.
HELLP syndrome, named for the symptoms associated with the condition—hemolysis, elevated liver enzymes, and low platelet count—may be a progression of preeclampsia but some researchers suggest it has a different etiology.
Risk: Preeclampsia is more common with first pregnancies, in women with previously diagnosed high blood pressure, and in those who have a family history of the condition. Middle-aged mothers (>40 years) are at increased risk of developing preeclampsia and eclampsia, and the risk ratio for blacks compared to whites is 1.5 to 1 (Lim). Failure to receive adequate prenatal care also is associated with an increased frequency of eclampsia (Ross). Risk appears to be greater in women who have a history of preeclampsia, preterm delivery, multiple gestations, or chronic hypertension. Other risk factors include obesity and chronic medical conditions such as diabetes, kidney disease, or antiphospholipid syndrome.
Incidence and Prevalence: In the US, preeclampsia affects roughly 5% of all pregnancies, and the incidence is 23.6 cases in 1,000 births (Erogul).
In developed countries, the incidence of preeclampsia is 4% to 18% (Lim). The incidence of eclampsia in developed countries varies from 1 in 1,000 pregnancies to 1 in 3,448 pregnancies (Ross).
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Source: Medical Disability Advisor