What are the diagnostic criteria for HELLP (Hemolysis, Elevated Liver enzymes, Low Platelet count) syndrome in pregnant women, particularly those with a history of preeclampsia or hypertension?

HELLP Syndrome Diagnostic Criteria

HELLP syndrome is diagnosed by the presence of three essential laboratory findings: hemolysis (confirmed by peripheral blood smear showing microangiopathic changes, elevated LDH, or low haptoglobin), elevated liver enzymes (AST/ALT significantly above normal), and thrombocytopenia with platelets below 100,000/mm³, after excluding other causes of these abnormalities. 1, 2

Core Diagnostic Components

Hemolysis Criteria

• Peripheral blood smear must demonstrate microangiopathic hemolytic anemia with schistocytes and fragmented red blood cells 3
• Elevated indirect bilirubin levels (may be up to 18 µmol/L or higher) 3
• Low serum haptoglobin levels indicating intravascular hemolysis 1
• Elevated lactate dehydrogenase (LDH) >295 U/L, which reflects both hemolysis extent and hepatic dysfunction 3, 4

Elevated Liver Enzymes

• Aspartate aminotransferase (AST) >200 U/L (normal range 0-40 U/L) 3
• Alanine aminotransferase (ALT) >159 U/L (normal range 0-45 U/L) 3
• AST, ALT, LDH, and total bilirubin are the most useful markers for disease progression 5
• The degree of liver enzyme elevation correlates with adverse maternal outcomes and necessitates urgent intervention 5

Thrombocytopenia

• Platelet count below 100,000/mm³ is the threshold for diagnosis 5, 1, 2
• Severe thrombocytopenia (<50,000/mm³) indicates active disease with significant maternal risk 5
• The degree of thrombocytopenia directly correlates with liver dysfunction severity and predicts adverse maternal outcomes 5
• Platelet count is one of the two most important clinical tools for disease assessment (along with LDH) 4

Associated Clinical Features

Common Presenting Symptoms

• Right upper quadrant or epigastric pain occurs in 65% of symptomatic patients and should immediately trigger imaging to rule out subcapsular hematoma or hepatic rupture 5, 6
• Nausea, vomiting, and gastrointestinal symptoms 3
• Hypertension (arterial pressure may progress from 130/80 to 160/95 mm Hg or higher) 3
• Proteinuria and peripheral edema (though these may be absent initially) 3, 2

Coagulation Studies

• Prothrombin time and activated partial thromboplastin time are typically normal 3
• Fibrinogen concentration remains normal 3
• Elevated fibrin degradation products (>80 µg/L, normal <10 µg/L) indicate microangiopathic process 3

Critical Diagnostic Pitfalls

Recognition Challenges

• HELLP syndrome may occur when usual clinical findings of severe preeclampsia are absent, leading to misdiagnosis with nonobstetric conditions 2
• Up to 30% of HELLP cases occur or worsen within 48 hours postpartum, requiring vigilant monitoring even after delivery 7, 5
• Delayed or missed diagnosis is life-threatening for both mother and child 6

Laboratory Monitoring Requirements

• Obtain complete blood count with platelets, comprehensive metabolic panel, LDH, and coagulation studies 7
• Continue laboratory monitoring every 6-12 hours for at least 24-48 hours postpartum 7, 5
• Persistent epigastric pain with worsening liver enzymes mandates immediate abdominal imaging (ultrasound or CT) to exclude subcapsular hematoma or hepatic rupture 7, 5

Disease Severity Assessment

High-Risk Features Requiring Immediate Action

• Severe thrombocytopenia (<50,000/mm³) with persistent right upper quadrant pain increases risk of hepatic hematoma or rupture 7
• Progressive thrombocytopenia and persistent symptoms beyond 5 days postpartum may indicate ongoing disease activity or hepatic complications 7
• Maternal mortality ranges from 2-24% with this syndrome, emphasizing the need for aggressive management 3