Balance Wk2 LG1 Hypertension Pathophysiology in Pregnancy

What is the central placental defect that begins the path toward preeclampsia?

Answer: Defective trophoblast invasion causes inadequate spiral-artery remodeling.

Extra Information:

• This is Stage 1 of the two-stage model.

• The initial problem is largely placental.

What normally happens to maternal spiral arteries during pregnancy?

Answer: Extravillous trophoblasts remodel them into wide, low-resistance vessels.

Extra Information:

• The muscular and elastic vessel wall is largely lost.
• This supports high-capacitance placental perfusion.

Which trophoblasts invade the maternal spiral arteries?

Answer: Extravillous trophoblasts.

Extra Information:

• Their invasion is necessary for normal spiral-artery remodeling.
• In preeclampsia, this invasion is abnormally shallow.

What happens to the smooth muscle and elastic tissue of spiral arteries during normal remodeling?

Answer: They are lost or replaced.

Extra Information:

• This reduces the arteries' ability to constrict.
• The result is a wide, low-resistance vessel.

How does the spiral-artery lumen change during normal pregnancy?

Answer: It becomes wider.

Extra Information:

• The wider lumen decreases resistance.
• This allows large-volume maternal blood flow to the intervillous space.

What is the functional result of normal spiral-artery remodeling?

Answer: High-capacitance, low-resistance blood flow to the intervillous space.

Extra Information:

• Maternal blood is delivered at lower velocity.
• Perfusion becomes more stable.

Why is normal spiral-artery remodeling important for placental function?

Answer: It provides steady, large-volume blood flow for stable oxygen and nutrient exchange.

Extra Information:

• Normal perfusion is relatively nonpulsatile.
• The goal is not simply more blood flow.

What type of blood flow should normal spiral arteries provide to the placenta?

Answer: High-capacitance, low-resistance, relatively nonpulsatile flow.

Extra Information:

• Blood is delivered at lower velocity into the intervillous space.
• This promotes stable exchange.

What happens to trophoblast invasion in preeclampsia?

Answer: Trophoblast invasion is abnormally shallow.

Extra Information:

• Fewer trophoblasts reach the deep myometrial segments.
• Spiral-artery transformation remains incomplete.

What happens to the muscular media of spiral arteries in preeclampsia?

Answer: The muscular media persists.

Extra Information:

• The musculoelastic wall is not fully replaced.
• The vessel therefore remains vasoreactive.

How does persistence of the muscular media affect spiral-artery resistance?

Answer: It increases resistance.

Extra Information:

• Persistent muscle maintains a narrow lumen.
• The artery also remains abnormally reactive.

What happens to spiral-artery pulsatility in preeclampsia?

Answer: Pulsatility remains abnormally high.

Extra Information:

• Normal remodeling should blunt vasoreactivity and pulsatility.
• High pulsatility contributes to abnormal placental inflow.

Which spiral-artery change most directly raises uteroplacental resistance?

Answer: Persistence of the muscular media.

Extra Information:

• Persistent muscle keeps the vessel narrow and vasoreactive.
• Normal loss of muscle lowers resistance.

How do normal and preeclamptic spiral arteries differ?

Answer: Normal arteries are wide and low resistance, while preeclamptic arteries remain narrow, muscular, reactive, and high resistance.

Extra Information:

• The difference results from adequate versus inadequate trophoblast invasion.
• This is the major Stage 1 abnormality.

What is Stage 1 of the two-stage model of preeclampsia?

Answer: Abnormal placentation causing placental malperfusion and stress.

Extra Information:

• Shallow trophoblast invasion causes poor spiral-artery remodeling.
• Stage 1 is largely placental.

What is Stage 2 of the two-stage model of preeclampsia?

Answer: Maternal systemic endothelial disease caused by circulating placental signals.

Extra Information:

• The endothelium is the shared maternal target.
• Different organs produce different clinical manifestations.

Trace Stage 1 of preeclampsia from trophoblast invasion to placental stress.

Answer: Shallow trophoblast invasion → inadequate spiral-artery remodeling → narrow reactive arteries → abnormal placental perfusion → placental stress.

Extra Information:

• Resistance and pulsatility remain high.
• Perfusion becomes intermittent.

Why do inadequately remodeled spiral arteries cause placental stress?

Answer: Their high resistance and pulsatility produce abnormal, intermittent placental perfusion.

Extra Information:

• The placenta experiences hypoxia-reoxygenation.
• This promotes cellular stress and injury.

What does placental hypoxia mean in the model presented in this lecture?

Answer: A broader pattern of placental malperfusion and cellular stress rather than simply continuously low oxygen.

Extra Information:

• Hypoxia-reoxygenation is emphasized.
• Abnormal perfusion creates oxidative and endoplasmic-reticulum stress.

What stresses develop from placental hypoxia-reoxygenation?

Answer: Oxidative stress and endoplasmic-reticulum stress.

Extra Information:

• These stresses contribute to syncytiotrophoblast injury.
• Placental mediators are then released into maternal blood.

What placental cell layer is injured by abnormal perfusion and cellular stress?

Answer: The syncytiotrophoblast.

Extra Information:

• Hypoxia-reoxygenation contributes to this injury.
• Injured placenta releases mediators into maternal circulation.

What is the clinically important consequence of placental stress?

Answer: Placental mediators are released into maternal blood.

Extra Information:

• These circulating signals connect the local placental lesion to systemic maternal disease.
• The major signal emphasized is angiogenic imbalance.

Trace the transition from abnormal spiral arteries to maternal endothelial disease.

Answer: Persistent muscular media → high-resistance flow → placental stress → angiogenic imbalance → maternal endothelial dysfunction.

Extra Information:

• The imbalance includes increased sFlt-1 and decreased free VEGF and PlGF.
• One placental defect can therefore affect the entire maternal circulation.

What are VEGF and PlGF in the preeclampsia model?

Answer: Proangiogenic ligands that support healthy endothelial signaling.

Extra Information:

• Their free availability supports endothelial stability.

• This is especially important in fenestrated vascular beds such as the glomerulus.

• VEGF = Vascular Endothelial Growth Factor → helps maintain healthy endothelial cells and blood vessels.

• PlGF = Placental Growth Factor → supports blood-vessel development, especially in the placenta.

What does VEGF normally support?

Answer: Endothelial survival and eNOS signaling.

Extra Information:

• VEGF comes from the placenta and other tissues.

• Free or bioavailable VEGF signaling is maintained in normal pregnancy.

eNOS = endothelial nitric oxide synthase.

It is an enzyme in endothelial cells that makes nitric oxide (NO).

eNOS → makes NO → vasodilation → ↓ vascular resistance → ↓ blood pressure

What does PlGF normally support?

Answer: Angiogenesis.

Extra Information:

• PlGF is released from the placenta into maternal blood.
• It normally rises toward midpregnancy and declines near term.

What does sFlt-1 do?

Answer: It acts as a soluble decoy receptor that traps free VEGF and PlGF.

Extra Information:

• sFlt-1 is soluble VEGFR-1.
• Ligand sequestration prevents normal endothelial signaling.

What does sFlt-1 stand for functionally in this lecture?

Answer: A soluble form of VEGFR-1 that sequesters VEGF and PlGF.

Extra Information:

• It prevents these ligands from reaching endothelial receptors.
• Its concentration rises markedly in preeclampsia.

What happens to sFlt-1 in preeclampsia?

Answer: sFlt-1 increases.

Extra Information:

• More VEGF and PlGF are trapped.
• The sFlt-1 to PlGF ratio therefore rises.

What happens to free VEGF in preeclampsia?

Answer: Free or bioavailable VEGF decreases.

Extra Information:

• Increased sFlt-1 sequesters VEGF.
• Total VEGF measurements can be assay-dependent.

What happens to PlGF in preeclampsia?

Answer: PlGF is decreased for gestational age.

Extra Information:

• Pregnancies that later develop preeclampsia can show lower PlGF before clinical disease.
• This contributes to angiogenic imbalance.

What is the central angiogenic imbalance in preeclampsia?

Answer: Increased sFlt-1 with decreased free VEGF and PlGF.

Extra Information:

• This disrupts endothelial signaling.
• Systemic endothelial dysfunction follows.

Trace the sFlt-1 mechanism from placental signal to endothelial dysfunction.

Answer: Increased sFlt-1 → VEGF and PlGF sequestration → decreased free VEGF and PlGF → reduced endothelial signaling → endothelial dysfunction.

Extra Information:

• This is the major bridge between Stage 1 and Stage 2.
• The effect occurs throughout the maternal circulation.

What is eNOS?

Answer: Endothelial nitric oxide synthase, the endothelial enzyme that produces nitric oxide from L-arginine.

Extra Information:

• Normal VEGF and PlGF signaling supports its activity.
• Its effective activity falls in preeclampsia.

What substrate does eNOS use to produce nitric oxide?

Answer: L-arginine.

Extra Information:

• eNOS is located in endothelial cells.
• Its product, nitric oxide, promotes vasodilation.

What happens to effective eNOS activity in preeclampsia?

Answer: It decreases.

Extra Information:

• Reduced VEGF and PlGF signaling contributes to the decrease.
• The lecture notes that eNOS expression itself can vary.

What does nitric oxide normally do to vascular smooth muscle?

Answer: It promotes vasodilation.

Extra Information:

• Nitric oxide travels from endothelium toward vascular smooth muscle.
• Its bioavailability is increased in normal pregnancy.

What happens to nitric oxide bioavailability in preeclampsia?

Answer: It decreases.

Extra Information:

• Reduced eNOS activity contributes to the decrease.
• Lower nitric oxide increases vascular tone.

Trace the nitric oxide mechanism linking angiogenic imbalance to vasoconstriction.

Answer: Increased sFlt-1 → decreased free VEGF and PlGF → decreased eNOS activity → decreased nitric oxide → vasoconstriction.

Extra Information:

• Vascular tone therefore rises.
• This pathway helps connect placental disease to maternal hypertension.

Why does decreased VEGF and PlGF signaling increase vascular tone?

Answer: It decreases eNOS activity and nitric oxide production.

Extra Information:

• Nitric oxide normally promotes vasodilation.
• Losing that vasodilatory influence favors vasoconstriction.

What happens to PlGF during normal pregnancy?

Answer: It rises toward midpregnancy and then declines near term.

Extra Information:

• PlGF supports angiogenesis.
• Its level is abnormally low for gestational age in preeclampsia.

What happens to sFlt-1 during normal pregnancy?

Answer: It remains relatively low and rises near term.

Extra Information:

• This differs from the marked increase seen with preeclampsia.
• sFlt-1 traps VEGF and PlGF.

When can PlGF become lower than expected in pregnancies that later develop preeclampsia?

Answer: Around 13 to 16 weeks.

Extra Information:

• The biomarker abnormality can precede clinical disease.
• Angiogenic imbalance develops before bedside criteria appear.

How does the timing of sFlt-1 elevation relate to clinical preeclampsia?

Answer: sFlt-1 can rise before hypertension and proteinuria appear.

Extra Information:

• The lecture depicts a rise around several weeks before clinical onset.
• Biomarkers support the two-stage model.

What does the sFlt-1 to PlGF ratio reflect?

Answer: The balance between antiangiogenic and proangiogenic signaling.

Extra Information:

• Higher sFlt-1 with lower PlGF produces a higher ratio.
• The ratio is interpreted with the clinical picture.

What does a lower sFlt-1 to PlGF ratio suggest?

Answer: A more balanced angiogenic signal with relatively preserved PlGF.

Extra Information:

• It can help rule out near-term disease.
• It is not used alone to diagnose preeclampsia.

What does a higher sFlt-1 to PlGF ratio suggest?

Answer: Greater angiogenic imbalance.

Extra Information:

• sFlt-1 is increased while PlGF is decreased.
• Risk and severity rise as the imbalance becomes more marked.

Why should the sFlt-1 to PlGF ratio not be used as a stand-alone diagnosis?

Answer: It must be interpreted with blood pressure, symptoms, proteinuria, laboratory findings, and gestational age.

Extra Information:

• The ratio reflects angiogenic balance rather than replacing clinical assessment.
• It functions as a clinical biomarker.

What is the shared maternal target of the placental antiangiogenic signal?

Answer: The vascular endothelium.

Extra Information:

• Endothelial dysfunction is the common pathophysiologic denominator.
• Different vascular beds produce different organ manifestations.

What four major endothelial functions are disrupted in preeclampsia?

Answer: Vasomotor tone, barrier function, the antithrombotic surface, and organ perfusion.

Extra Information:

• Their disruption explains the multisystem presentation.

• Endothelial dysfunction is the unifying lesion.

How is vasomotor function altered in preeclampsia?

Answer: Vasodilatory signaling falls and vasoconstrictor responses increase.

Extra Information:

• Nitric oxide signaling decreases.
• Systemic vascular resistance rises.

How is endothelial barrier function altered in preeclampsia?

Answer: Endothelial permeability increases.

Extra Information:

• Increased permeability promotes capillary leak.
• This contributes to edema.

How is the normal antithrombotic endothelial surface altered in preeclampsia?

Answer: It becomes a surface that promotes platelet activation and microvascular fibrin deposition.

Extra Information:

• This is especially important in HELLP syndrome.
• Platelets are consumed in injured microvessels.

How does endothelial dysfunction alter organ perfusion?

Answer: It can cause ischemia, edema, and end-organ dysfunction.

Extra Information:

• The specific manifestation depends on the vascular bed involved.
• This explains the multisystem nature of preeclampsia.

Why does blood pressure rise in preeclampsia?

Answer: Systemic vascular resistance increases because endothelial dysfunction favors vasoconstriction.

Extra Information:

• Reduced nitric oxide and prostacyclin effects contribute.
• Vasoconstrictor sensitivity also increases.

Trace the mechanism of hypertension in preeclampsia.

Answer: Antiangiogenic state → endothelial injury → decreased vasodilators → increased vasoconstriction → increased systemic vascular resistance → increased blood pressure.

Extra Information:

• Nitric oxide and prostacyclin effects are reduced.
• Endothelin sensitivity increases.

What happens to systemic vascular resistance in preeclampsia?

Answer: It increases.

Extra Information:

• Increased systemic vascular resistance raises blood pressure.
• It also increases afterload and organ stress.

How does endothelin contribute to hypertension in preeclampsia?

Answer: The vasculature develops greater sensitivity to endothelin-mediated vasoconstriction.

Extra Information:

• This occurs alongside loss of vasodilatory signaling.
• The net effect is increased vascular tone.

Does hypertension in preeclampsia require an abnormally high circulating blood volume?

Answer: No. Blood pressure rises primarily because systemic vascular resistance increases.

Extra Information:

• High blood pressure does not necessarily mean the circulation contains excess volume.
• Increased vascular tone is the key mechanism emphasized.

What is the characteristic renal lesion of preeclampsia?

Answer: Glomerular endotheliosis.

Extra Information:

• Glomerular endothelial cells become swollen.
• Capillary lumens become narrowed.

What happens to glomerular endothelial cells in glomerular endotheliosis?

Answer: They swell.

Extra Information:

• The glomerular capillary lumens become narrowed.
• Filtration surface and barrier function are disrupted.

What happens to glomerular capillary lumens in preeclampsia?

Answer: They become narrowed.

Extra Information:

• Endothelial swelling reduces capillary space.
• Renal perfusion and filtration can decline.

Why does preeclampsia cause proteinuria?

Answer: Glomerular endothelial injury disrupts filtration-barrier selectivity, allowing albumin to enter the urine.

Extra Information:

• The lesion is glomerular endotheliosis.
• Fenestrated glomerular endothelium is particularly dependent on healthy VEGF signaling.

Why is the glomerulus especially vulnerable to reduced VEGF signaling?

Answer: It is a fenestrated endothelial bed that depends on VEGF-supported endothelial health.

Extra Information:

• Reduced free VEGF contributes to glomerular endothelial dysfunction.
• Glomerular endotheliosis can result.

What happens to renal perfusion and GFR in preeclampsia?

Answer: They may decrease.

Extra Information:

• Swollen endothelial cells narrow glomerular capillary lumens.
• Reduced filtration can accompany proteinuria.

Trace the mechanism of proteinuria in preeclampsia.

Answer: Angiogenic imbalance → glomerular endothelial dysfunction → glomerular endotheliosis → disrupted barrier selectivity → albumin enters urine.

Extra Information:

• Endothelial swelling also narrows capillary lumens.
• GFR may decline.

Why does edema occur in preeclampsia?

Answer: Increased capillary permeability causes fluid to leave the vascular space, while protein loss can further reduce plasma oncotic pressure.

Extra Information:

• Both barrier failure and Starling forces contribute.
• Edema is not required for diagnosis.

What is the primary endothelial contribution to edema in preeclampsia?

Answer: Increased capillary permeability and capillary leak.

Extra Information:

• Endothelial barrier function is impaired.
• Fluid therefore moves from the vascular space into the interstitium.

How does proteinuria worsen edema in preeclampsia?

Answer: Protein loss lowers plasma oncotic pressure, reducing the force that keeps fluid in the vascular space.

Extra Information:

• This favors movement of fluid into the interstitium.
• It adds to the effect of increased capillary permeability.

Is edema required to diagnose preeclampsia?

Answer: No.

Extra Information:

• Edema is common even in normal pregnancy.
• Its presence alone is therefore not diagnostic.

What is the clinical triad emphasized in this lecture?

Answer: Hypertension, proteinuria, and edema.

Extra Information:

• All three can be traced to endothelial dysfunction.
• Edema is not required for the clinical diagnosis.

Match the preeclampsia triad to its most direct endothelial mechanism.

Answer: Hypertension = vasoconstriction and increased SVR. Proteinuria = glomerular endotheliosis. Edema = capillary leak.

Extra Information:

• These are different expressions of the same systemic endothelial disease.

• The shared upstream cause is the placental antiangiogenic signal.

How can one placental disorder produce disease in many maternal organs?

Answer: Placental mediators enter maternal blood and cause systemic endothelial dysfunction.

Extra Information:

• Every vascular bed can therefore become a target.
• The affected organ determines the clinical phenotype.

What endothelial abnormalities occur in the brain during severe preeclampsia?

Answer: Blood-brain barrier dysfunction and failure of cerebral autoregulation.

Extra Information:

• These changes can cause headache, visual symptoms, edema, and seizure.
• They are central to eclampsia.

What endothelial abnormalities occur in the liver during severe preeclampsia?

Answer: Sinusoidal obstruction and ischemic injury.

Extra Information:

• These can cause right upper quadrant pain and elevated AST and ALT.
• Severe injury can produce a subcapsular hematoma.

What blood abnormality results from severe endothelial microvascular injury?

Answer: Microangiopathy with platelet consumption.

Extra Information:

• Red blood cells can fragment as they traverse injured vessels.

• Schistocytes, hemolysis, and thrombocytopenia can result.

Microangiopathy is a medical condition that damages and narrows the tiny blood vessels, known as capillaries and arterioles, throughout the body.

Microangiopathic hemolytic anemia (MAHA) is a medical condition where red blood cells are physically damaged and destroyed as they flow through narrowed or blocked small blood vessels

How can preeclampsia affect the lungs?

Answer: Capillary leak and hydrostatic stress can cause pulmonary edema.

Extra Information:

• Systemic endothelial barrier dysfunction contributes.
• Pulmonary edema represents another organ expression of the disease.

How can preeclampsia affect the placenta and fetus?

Answer: Placental malperfusion can cause fetal growth restriction and placental abruption.

Extra Information:

• Abnormal spiral-artery remodeling is the upstream placental lesion.
• Placental perfusion remains abnormal.

What does HELLP stand for?

Answer: Hemolysis, Elevated Liver enzymes, and Low Platelets.

Extra Information:

• HELLP is a severe thrombotic microangiopathic phenotype.
• It reflects endothelial injury in blood and hepatic microvasculature.

What is the basic vascular mechanism of HELLP syndrome?

Answer: Endothelial injury activates the microvascular surface, causing platelet adhesion, fibrin deposition, and small-vessel obstruction.

Extra Information:

• Red cells are damaged passing through narrowed vessels.
• Hepatic microvascular flow is also impaired.

Trace the overall mechanism of HELLP syndrome.

Answer: Endothelial injury → platelet adhesion and fibrin deposition → small-vessel obstruction → red-cell shear and hepatic ischemia → hemolysis, elevated liver enzymes, and low platelets.

Extra Information:

• HELLP is therefore a multisystem microangiopathic process.
• Its components arise from the same endothelial lesion.

What type of hemolysis occurs in HELLP syndrome?

Answer: Microangiopathic hemolytic anemia.

Extra Information:

• Red blood cells are mechanically damaged in narrowed, fibrin-rich microvessels.
• Schistocytes result.

Why do red blood cells fragment in HELLP syndrome?

Answer: They are sheared while passing through narrowed, fibrin-rich injured microvessels.

Extra Information:

• The process is microangiopathic.
• Fragmented red cells are called schistocytes.

What are schistocytes?

Answer: Fragmented red blood cells produced by mechanical shear in injured microvessels.

Extra Information:

• They support microangiopathic hemolysis.

• They can appear on the peripheral blood smear in HELLP.

What happens to LDH during HELLP-associated hemolysis?

Answer: LDH increases.

Extra Information:

• Red-cell destruction contributes to the elevation.

• Increased LDH supports hemolysis.

LDH = lactate dehydrogenase.

It’s an enzyme found inside many cells. When cells are damaged or red blood cells are destroyed (hemolysis), LDH leaks into the blood → ↑ LDH.

What happens to bilirubin during HELLP-associated hemolysis?

Answer: Bilirubin increases.

Extra Information:

• Red-cell destruction increases bilirubin production.

• It is another laboratory clue for hemolysis.

Bilirubin is a yellow waste product made when old or damaged red blood cells are broken down.

Think of the pathway:

Red blood cell breaks down
→ hemoglobin released
→ heme portion is broken down
→ bilirubin is produced
→ liver processes bilirubin
→ bilirubin eventually leaves through bile/stool

What happens to haptoglobin during intravascular hemolysis in HELLP?

Answer: Haptoglobin decreases.

Extra Information:

• Haptoglobin binds free hemoglobin.

• It is consumed as free hemoglobin is released from destroyed red cells.

🧠 Think: Haptoglobin “haptures” (captures) hemoglobin.

Normally, hemoglobin should stay inside red blood cells. If red blood cells break apart:

Hemolysis
→ hemoglobin spills into the blood
→ haptoglobin binds that free hemoglobin
→ the haptoglobin–hemoglobin complex gets cleared from the blood
→ haptoglobin level ↓

Why does haptoglobin decrease during HELLP-associated hemolysis?

Answer: Haptoglobin is consumed while binding free hemoglobin released from damaged red blood cells.

Extra Information:

• The result is a low circulating haptoglobin level.
• This supports intravascular hemolysis.

What laboratory pattern supports hemolysis in HELLP?

Answer: Schistocytes with increased LDH and bilirubin and decreased haptoglobin.

Extra Information:

• These findings reflect red-cell destruction.
• The mechanism is microangiopathic shear.

What begins the hepatic injury of HELLP syndrome?

Answer: Sinusoidal endothelial injury.

Extra Information:

• Endothelial barrier and antithrombotic functions fail.

• Fibrin and platelets accumulate in hepatic microvessels.

Sinusoidal endothelial injury means damage to the endothelial cells lining the liver’s sinusoids.

The sinusoids are tiny, specialized blood vessels inside the liver that blood flows through.

Why does hepatic microvascular flow become obstructed in HELLP?

Answer: Fibrin and platelet deposition narrow the injured sinusoidal microvasculature.

Extra Information:

• This impairs hepatic blood flow.
• Ischemia and congestion can follow.

Why do AST and ALT rise in HELLP syndrome?

Answer: Hepatic microvascular obstruction causes ischemic hepatocyte injury.

Extra Information:

• Injured hepatocytes release liver enzymes.
• The underlying process begins with sinusoidal endothelial injury.

Why can HELLP syndrome cause right upper quadrant or epigastric pain?

Answer: Hepatic congestion, ischemia, and hemorrhagic injury can produce pain.

Extra Information:

• The liver is a major target organ in HELLP.
• Severe disease can produce a subcapsular hematoma.

What is a subcapsular hepatic hematoma in severe HELLP?

Answer: A collection of blood beneath the liver capsule caused by severe hepatic vascular injury and hemorrhage.

Extra Information:

• It is a rare severe complication.
• Rupture can occur.

Trace hepatic injury in HELLP from endothelial damage to liver-enzyme elevation.

Answer: Sinusoidal endothelial injury → fibrin and platelet deposition → microvascular obstruction → hepatic ischemia → hepatocyte injury → increased AST and ALT.

Extra Information:

• Congestion and hemorrhage may also occur.
• Severe disease can cause subcapsular hematoma or rupture.

Why are platelets low in HELLP syndrome?

Answer: Platelets are consumed as they adhere and aggregate in injured microvessels.

Extra Information:

• Platelet-rich microthrombi form.
• The problem is peripheral consumption rather than primary underproduction.

Are low platelets in HELLP primarily caused by bone-marrow failure?

Answer: No. They are primarily caused by peripheral platelet consumption.

Extra Information:

• Endothelial injury creates an adhesive, procoagulant surface.
• Platelets are activated and incorporated into microthrombi.

Trace the mechanism of thrombocytopenia in HELLP.

Answer: Endothelial injury → platelet activation → adhesion and aggregation → platelet-rich microthrombi → platelet consumption → thrombocytopenia.

Extra Information:

• The circulating platelet count falls because platelets are being used.
• This is not primarily a production problem.

What is eclampsia?

Answer: A seizure attributed to the hypertensive disorder of pregnancy.

Extra Information:

• It is not simply defined as an extremely high blood pressure.
• Cerebral endothelial and autoregulatory dysfunction are central.

What happens to the blood-brain barrier in eclampsia?

Answer: Cerebral endothelial injury makes the blood-brain barrier abnormally permeable.

Extra Information:

• Fluid can cross the barrier.
• This contributes to vasogenic cerebral edema.