Preeclampsia is a complication of pregnancy. In preeclampsia, the woman has dangerously high blood pressure, swelling (edema) and protein in the urine (proteinuria). Blood pressure rises from 140/90 mm Hg to 160/110 mm Hg. High blood pressure is first noted sometime after week 20 of pregnancy and is accompanied by protein in the urine (2g of protein in 24 hour urine or 2+ to 3+ on qualitative examination)
Preeclampsia is most common among women who have never given birth to a baby (called nulliparas). About 7% of all nulliparas develop preeclampsia. The disease is most common in mothers under the age of 20 or over the age of 35. Other risk factors include poverty, multiple pregnancies (twins, triplets, etc.), pre-existing chronic hypertension or kidney disease, diabetes, excess amniotic fluid, and a condition of the fetus called nonimmune hydrops. The tendency to develop preeclampsia appears to run in families. The daughters and sisters of women who have had preeclampsia are more likely to develop the condition.
Causes and symptoms
Experts are still trying to understand the exact causes of preeclampsia and eclampsia. It is believed that Preeclampsia will occur when there is a failure of the placenta decidua to invade the smooth muscle (Tunica Media) of the maternal blood vessels and replace the endothelial cells; This would normally allow for increase blood flow to the fetus and prevent “leaky” blood vessels due to high intravascular pressures. It is generally accepted that preeclampsia and eclampsia in general are problematic because these conditions cause blood vessels to leak. The effects are seen throughout the body.
- General body tissues.
When blood vessels leak, they allow fluid to flow out into the tissues of the body. The result is swelling in the hands, feet, legs, arms, and face. While many pregnant women experience swelling in their feet, and sometimes in their hands, swelling of the upper limbs and face is a sign of a more serious problem. As fluid is retained in these tissues, the woman may experience significant weight gain (two or more pounds per week).
- Brain. Leaky vessels can cause damage within the brain, resulting in seizures or coma.
- Eyes. The woman may experience problems seeing, and may have blurry vision or may see spots. The retina may become detached.
- Lungs. Fluid may leak into the tissues of the lungs, resulting in shortness of breath.
- Liver.Leaky vessels within the liver may cause it to swell. The liver may be involved in a serious complication of preeclampsia, called the HELLP syndrome. In this syndrome, red blood cells are abnormally destroyed (anemia), chemicals called liver enzymes are abnormally high, and cells involved in
the clotting of blood (platelets) are low.
- Kidneys.The small capillaries within the kidneys can leak. Normally, the filtration system within the kidney is too fine to allow protein (which is relatively large) to leave the bloodstream and enter the urine. In
preeclampsia, however, the leaky capillaries allow protein to be dumped into the urine. The development of protein in the urine is very serious, and often results in a low birth weight baby. These babies have a higher risk of complications, including death.
- Blood pressure.In preeclampsia, the volume of circulating blood is lower than normal because fluid is leaking into other parts of the body. The heart tries to make up for this by pumping a larger quantity of blood with each contraction. Blood vessels usually expand in diameter (dilate) in this situation to decrease the work load on the heart. In preeclampsia, however, the blood vessels are abnormally constricted, causing the heart to work even harder to pump against the small diameters of the vessels.
This causes an increase in blood pressure.
The most serious consequences of preeclampsia and eclampsia include brain damage in the mother due to brain swelling and oxygen deprivation during seizures. Mothers can also experience blindness, kidney failure, liver rupture, and placental abruption. Babies born to preeclamptic mothers are often smaller than normal, which makes them more susceptible to complications during labor, delivery, and in early infancy. Babies of preeclamptic mothers are also at risk of being born prematurely, and can suffer the complications associated with prematurity.
The prognosis in pre eclampsia (and eclampsia) depends on how carefully a patient is monitored. Very careful, consistent monitoring allows quick decisions to be made, and improves the woman’s prognosis. Still, the most common causes of death in pregnant women are related to high blood pressure. About 33% of all patients with preeclampsia will have the condition again with later pregnancies. Eclampsia occurs in about 1 out of every 200 women with preeclampsia. If not treated, eclampsia is almost always fatal.