Preeclampsia and eclampsia
- Mechanism
A poorly built placenta releases factors that damage the mother's blood vessels; blood pressure rises and organs fail until the placenta is delivered.
What it is
Preeclampsia is a pregnancy syndrome of new hypertension after 20 weeks with proteinuria or other organ dysfunction; eclampsia adds seizures, and HELLP syndrome adds haemolysis, raised liver enzymes and low platelets. Its root is an abnormal placenta: the trophoblast fails to remodel the maternal spiral arteries, the placenta becomes ischaemic and releases antiangiogenic proteins, soluble Flt-1 and soluble endoglin, that block VEGF, PlGF and TGF-beta signalling. The result is widespread endothelial dysfunction, vasoconstriction, leaky vessels and clotting. Delivery of the placenta is the cure.
Structure
- Placenta: small for gestational age; infarcts, retroplacental haematoma, distal villous hypoplasia, accelerated maturation and increased syncytial knots.
- Decidual arteries: fibrinoid necrosis with lipid-laden macrophages (acute atherosis) and no physiologic remodelling.
- Kidney: enlarged bloodless glomeruli with swollen endothelial cells and subendothelial fibrin.
- Liver: fibrin thrombi in periportal sinusoids with haemorrhagic necrosis.
Step by step
- In early pregnancy, extravillous trophoblast fails to invade and remodel the spiral arteries.
- The arteries stay narrow and muscular; the placenta suffers ischaemia and oxidative stress.
- The stressed placenta releases soluble Flt-1 and soluble endoglin into the maternal blood.
- These factors neutralise VEGF, PlGF and TGF-beta, which keep the endothelium healthy.
- Systemic endothelial dysfunction causes vasoconstriction (hypertension), leaky capillaries (proteinuria, oedema) and platelet and coagulation activation.
- Organ damage follows: kidney, liver, brain, placenta; HELLP and DIC in severe cases.
Clinical notes
- Risk factors: first pregnancy, previous preeclampsia, chronic hypertension, diabetes, kidney disease, obesity, antiphospholipid syndrome, multiple or molar pregnancy, older maternal age.
- Warning signs: severe headache, visual disturbance, epigastric or right upper quadrant pain, rising blood pressure; seizures mean eclampsia.
- Hypertensive disorders of pregnancy are a leading cause of maternal death in Colombia and Latin America; women with preeclampsia carry a higher lifelong cardiovascular risk.
Test yourself
Think of the answer, then tap the question to see it.
What placental abnormality underlies preeclampsia?
Failure of trophoblast to remodel the spiral arteries, which stay narrow and muscular and leave the placenta ischaemic.
How do soluble Flt-1 and soluble endoglin cause the maternal disease?
They trap VEGF and PlGF and block TGF-beta signalling, which the endothelium needs, producing systemic endothelial dysfunction.
What is the typical kidney lesion of preeclampsia?
Glomerular endotheliosis: swollen endothelial cells occluding the capillary lumens, with proteinuria.
What is HELLP syndrome?
A severe form with haemolysis, elevated liver enzymes and low platelets, from microangiopathy and periportal liver injury.
Elsewhere in DurgiPedia
- Maternal physiological changes in pregnancy
- Placenta: structure, circulation and functions
- The placenta and pregnancy hormones
- Placenta
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Preeclampsia (StatPearls (NCBI Bookshelf), 2026).
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Representative model, for educational purposes only.