Pre-eclampsia/Eclampsia Pathophysiology and Diagnosis

Etiology and Pathophysiologic Mechanisms

• The American Heart Association suggests that pre-eclampsia results from abnormal placentation leading to placental hypoxia, which triggers release of anti-angiogenic factors into maternal circulation, causing widespread endothelial dysfunction and multi-organ involvement 1, 2
• Defective placentation, characterized by incomplete transformation of maternal spiral arteries, occurs due to shallow cytotrophoblast invasion, resulting in high-resistance uteroplacental circulation and reduced placental perfusion, as noted by the European Society of Cardiology 3, 4
• The European Society of Cardiology also states that angiogenic imbalance, caused by the hypoxic placenta releasing excessive soluble fms-like tyrosine kinase-1 (sFlt-1), leads to deficiency of pro-angiogenic factors, contributing to the development of pre-eclampsia 3, 4

Risk Factors and Diagnostic Criteria

• The American College of Obstetricians and Gynecologists identifies obstetric factors, such as first pregnancy, multiple gestation, and history of pre-eclampsia in previous pregnancy, as risk factors for pre-eclampsia 3, 4
• Medical comorbidities, including pre-existing chronic hypertension, diabetes mellitus, and chronic kidney disease, increase the risk of pre-eclampsia, according to the American Heart Association 1, 4
• Demographic factors, such as maternal age >40 years and family history of pre-eclampsia, also contribute to the risk of developing pre-eclampsia, as noted by the European Society of Cardiology 3, 4
• The European Society of Cardiology defines pre-eclampsia as new-onset hypertension (BP ≥140/90 mmHg) developing after 20 weeks gestation, accompanied by either proteinuria (≥0.3 g/24 hours) or evidence of maternal organ dysfunction 3, 4, 1

Clinical Manifestations and Laboratory Abnormalities

• The American College of Obstetricians and Gynecologists states that mild to moderate pre-eclampsia is characterized by blood pressure 140-159/90-109 mmHg, proteinuria ≥0.3 g/24 hours, and edema, while severe pre-eclampsia features include severe hypertension, hepatic involvement, and neurological manifestations 3, 1
• Severe pre-eclampsia is associated with cardiovascular, hepatic, and neurological manifestations, including severe hypertension, liver capsule distension, and visual disturbances, as noted by the European Society of Cardiology 3, 1, 5
• Laboratory abnormalities, such as proteinuria, elevated serum creatinine, and thrombocytopenia, are commonly seen in pre-eclampsia, according to the American Heart Association 1, 4
• The European Society of Cardiology also notes that elevated liver transaminases, elevated LDH, and decreased haptoglobin are indicative of hemolysis and liver dysfunction in pre-eclampsia 3, 1

Elevated Liver Enzymes in Preeclampsia

Pathophysiology

• Elevated liver enzymes in preeclampsia result from hepatic ischemia and necrosis caused by widespread endothelial dysfunction, vasospasm, and reduced organ perfusion—a direct consequence of the systemic inflammatory response triggered by placental hypoperfusion and release of anti-angiogenic factors, as recommended by the European Society of Cardiology 6, 7
• Activation of the coagulation cascade further compromises hepatic microcirculation, according to the European Society of Cardiology 6, 7

Clinical Manifestations

• Elevated lactate dehydrogenase (LDH) indicates both hepatocellular damage and hemolysis, as reported by the American Heart Association 8, 9
• Right upper quadrant or epigastric pain results from liver capsule distension due to hepatic edema and subcapsular hemorrhage, as stated by the European Society of Cardiology 6, 7

Severity Correlation

• The degree of liver enzyme elevation correlates with disease severity, with severe preeclampsia demonstrating more pronounced elevations with abnormal liver enzymes as a diagnostic criterion, according to the American Heart Association 8, 10
• Thrombocytopenia (<100,000/μL) combined with elevated liver enzymes indicates severe maternal organ dysfunction requiring delivery consideration, as recommended by the American Heart Association 8, 9

HELLP Syndrome

• HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets) represents the severe end of the preeclampsia spectrum, signifying more serious disease but remaining part of preeclampsia, not a separate disorder, as stated by the American Heart Association 6, 7, 8

Preeclampsia and Epigastric Pain

Clinical Significance

• The American College of Obstetricians and Gynecologists recommends that the presence of epigastric or right upper quadrant pain in a pregnant woman after 20 weeks' gestation should immediately trigger suspicion for severe preeclampsia or HELLP syndrome, regardless of whether classic signs of preeclampsia are present 11
• The Society of Obstetricians and Gynaecologists of Canada suggests that epigastric pain is a symptom of severe preeclampsia and indicates significant hepatic involvement requiring urgent evaluation 12

Critical Diagnostic Approach

• The American Heart Association recommends that all pregnant women with epigastric or right upper quadrant pain after 20 weeks' gestation must undergo immediate laboratory evaluation to rule out preeclampsia/HELLP syndrome, including complete blood count with platelet count, liver enzymes, serum creatinine and uric acid, and urinalysis with protein quantification 12

Imaging Requirements

• The American Institute of Ultrasound in Medicine recommends that abdominal ultrasound should be performed in women with severe preeclampsia or HELLP syndrome if there are symptoms suggestive of hepatic hematoma, specifically abdominal, epigastric, or right shoulder pain 11

Management Implications

• The National Institute for Health and Care Excellence recommends that once severe preeclampsia or HELLP syndrome with epigastric pain is diagnosed, prompt delivery after maternal stabilization is the definitive treatment, and initiation of magnesium sulfate for seizure prophylaxis, control of severe hypertension, and performance of abdominal imaging to rule out hepatic hemorrhage, infarct, or rupture are immediate actions required 11

Two‑Stage Cascade Model and Endothelial Dysfunction in Preeclampsia

Placental Ischemia (Stage 1)

• Abnormal shallow trophoblast invasion leads to high‑resistance uteroplacental circulation, causing placental hypoxia and oxidative stress that trigger release of pathogenic factors into the maternal circulation. 13

Maternal Systemic Response (Stage 2)

• The stressed placenta releases excess soluble fms‑like tyrosine kinase‑1 (sFlt‑1) and soluble endoglin, which neutralize VEGF and PlGF, producing a systemic angiogenic imbalance that underlies widespread endothelial dysfunction. 13

Hematologic Manifestations

• Platelet consumption occurs via activation of the coagulation cascade and accelerated platelet turnover secondary to diffuse endothelial injury. 14
• Platelet volume is increased in preeclampsia, reflecting heightened turnover and consumption. 14
• Formation of microthrombi throughout the microcirculation further depletes circulating platelets. 14

Hepatic Manifestations

• Endothelial dysfunction reduces hepatic arterial and portal blood flow, leading to hepatocellular ischemia and necrosis. 14

Renal Manifestations

• Glomerular endotheliosis—characterized by glomerular enlargement from endothelial cell hypertrophy—is the pathognomonic renal lesion of preeclampsia. 14
• A decline in glomerular filtration rate occurs before clinical diagnosis, reflecting volume‑expanded circulation in affected women. 15
• Accelerated loss of plasma protein from the vascular compartment contributes to reduced effective plasma volume. 14

Pulmonary Manifestations

• Increased pulmonary capillary permeability, combined with hypo‑oncotic plasma from proteinuria and iatrogenic fluid overload, results in pulmonary edema. 14

Cardiovascular and Coagulation Effects

• Despite normal endogenous pressor levels, heightened sensitivity to circulating vasoconstrictors produces generalized vasoconstriction in preeclampsia. 14
• Widespread vasoconstriction diminishes perfusion to kidneys, liver, brain, and heart, predisposing to organ ischemia and necrosis. 14
• Subendocardial necrosis resembling hypovolemic shock can develop in the maternal heart. 14
• Sensitive laboratory markers of coagulation activation are detectable in most preeclamptic women, although overt consumptive coagulopathy is observed in only about 10 % of cases. 14
• Microthrombi formation further impairs perfusion of vital organs. 14