Preeclampsia & eclampsia – causes, symptoms, diagnosis, treatment, pathology

Preeclampsia & eclampsia – causes, symptoms, diagnosis, treatment, pathology

September 2, 2019 100 By Bertrand Dibbert


Preeclampsia is a disorder that only happens
in pregnant women – it occurs after 20 weeks’ gestation, and in some cases develops up to
6 weeks after delivery. Preeclampsia causes new-onset hypertension
and proteinuria – protein in the urine, which is a marker of kidney damage – and can also
cause damage to other organs like the brain and liver. There can be a wide range of symptoms – for
some women there may be no symptoms or only mild ones, whereas for others, it can turn
into a life-threatening illness. If a woman with preeclampsia develops seizures,
she is said to have eclampsia. Preeclampsia tends to occur more often during
a first pregnancy, in pregnancies with multiple gestations, or in mothers 35 years or older. Other risk factors include having hypertension,
diabetes, obesity, or a family history of preeclampsia. Okay but why do these changes happen in preeclampsia
and eclampsia? Well, the exact cause is unclear, a key pathophysiologic
feature though is the development of an abnormal placenta. Normally, during pregnancy, the spiral arteries
dilate to 5-10 times their normal size and develop into large uteroplacental arteries
capable of delivering large quantities of blood to the developing fetus. In preeclampsia, these uteroplacental arteries
become fibrous causing them to narrow, which means less blood gets to the placenta. A poorly perfused placenta can lead to intrauterine
growth restriction and even fetal death in severe cases. At this point, the hypoperfused placenta starts
releasing pro-inflammatory proteins. These thenn get intol the mother’s circulation
and cause the endothelial cells that line her blood vessels to become dysfunctional. Endothelial cell dysfunction causes vasoconstriction
– narrowing of the blood vessels – and also affects the kidneys in a way that makes them
retain more salt, both of which result in hypertension. When diagnosing preeclampsia, hypertension
is defined as a systolic blood pressure of 140 mmHg or greater or diastolic blood pressure
of 90 mmHg or greater. In severe preeclampsia, systolic blood pressure
can be 160 mmHg or greater and diastolic blood pressure can be 110 mmHg or greater. These extreme blood pressures can lead to
a hemorrhagic stroke or placental abruption, in which the placenta detaches prematurely
from the uterine wall. There can also be local areas of vasospasm
– which means that less blood might reach certain parts of the body. For example, reduced blood flow to the kidneys,
which are particularly susceptible, can cause glomerular damage leading to oliguria – very
little urine – and proteinuria . Normally, the glomeruli of the kidneys do a good job
of preventing protein from spilling into the urine, so proteinuria can be a sign of glomerular
damage and is a classic sign of preeclampsia. Reduced blood flow to the retina can cause
blurred vision, the sensation of seeing flashing lights, and the development of a scotoma. A scotoma is when a small part of the visual
field has slightly worse visual acuity – a bit like having a blurry spot on an otherwise
normal computer monitor. Reduced blood flow to the liver can cause
severe liver injury and swelling, which can cause an elevation in liver enzymes and stretches
out the capsule around the liver. Stretching of the liver capsule typically
causes right upper quadrant pain, or epigastric pain, which is one of the cardinal symptoms
of severe preeclampsia. Endothelial injury also leads to the formation
of lots of tiny thrombi in the microvasculature, a process that uses up massive amounts of
platelets. Having all of these tiny blood clots in the
blood is a bit like having dozens of boulders in the middle of a fast moving river. It becomes treacherous for red blood cells
to navigate through, and before long, they slam up against a clot and get destroyed – a
process called hemolysis. Together these make up HELLP syndrome (H=hemolysis,
EL=elevated liver enzymes, LP=low platelets). HELLP syndrome develops in about 10 to 20%
of women with severe preeclampsia or eclampsia. Finally, endothelial injury increases vascular
permeability, allowing water to slip out of blood vessels between neighboring endothelial
cells and get into the tissues. Because there’s also a loss of protein from
the blood due to the proteinuria, even more fluid moves from the blood vessels into the
tissues. This causes generalized edema which is often
seen in the legs, face and hands; pulmonary edema which can cause cough and shortness
of breath; and cerebral edema which can cause headache, confusion, and seizures. Seizures define the onset of eclampsia. Because all of the problems of preeclampsia
and eclampsia stem from placental dysfunction, the ultimate treatment is delivery of the
fetus and placenta. The decision to induce delivery depends heavily
on the gestational age of the fetus as well as the severity of the disease and how it’s
affecting both maternal and fetal health. If the onset of symptoms comes after delivery,
then the goal is to manage the symptoms which slowly subside on their own. Additional measures are aimed at managing
any end-organ damage by offering supplemental oxygen, medication to manage seizures, and
other complications like stroke or placental abruption. As a quick recap, preeclampsia is a disorder
that occurs after 20 weeks’ gestation and up to 6 weeks following delivery. It is defined by a new onset of hypertension
and proteinuria but can affect many organs, particularly the kidneys, eyes, liver, and
brain. Eclampsia is diagnosed when a patient with
preeclampsia develops seizures. Thanks for watching, you can help support
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