What is the difference between preeclampsia and HELLP (Hemolysis, Elevated Liver enzymes, Low Platelet count) syndrome in pregnant women, particularly those with a history of hypertension, diabetes, or renal disease?

HELLP Syndrome is a Manifestation of Severe Preeclampsia, Not a Separate Disease Entity

HELLP syndrome should be considered a manifestation of severe preeclampsia rather than a distinct disorder. 1 This classification approach reduces confusion and ensures that clinicians recognize HELLP as part of the preeclampsia spectrum, prompting them to seek and address all other features of preeclampsia when HELLP is identified. 1

Key Conceptual Difference

Preeclampsia Definition

Preeclampsia is gestational hypertension (≥140/90 mmHg) developing at or after 20 weeks' gestation, accompanied by one or more of the following new-onset conditions: 1

• Proteinuria (present in approximately 75% of cases) 1
• Renal insufficiency
• Liver involvement (elevated transaminases)
• Neurological complications (headache, visual disturbances, altered mental status)
• Hematological complications (thrombocytopenia)
• Uteroplacental dysfunction (fetal growth restriction)

HELLP Syndrome as Severe Preeclampsia

HELLP represents a specific constellation of laboratory abnormalities that signifies a more serious part of the preeclampsia spectrum: 1

• Hemolysis (schistocytes on smear, elevated LDH >600 IU/L, elevated bilirubin >12 mg/L) 2, 3
• ELevated Liver enzymes (elevated AST/ALT indicating hepatic dysfunction) 1, 4
• LP Low Platelets (<100,000/mm³) 1, 4, 2

Critical Clinical Distinctions

Presentation Patterns

HELLP can present atypically in ways that differ from classic preeclampsia: 4

• 15% of HELLP cases occur without hypertension 4
• 30% of HELLP cases occur or worsen postpartum (20% within 48 hours of delivery) 4, 5
• 10-20% can be diagnosed in the absence of preeclampsia features 2
• Proteinuria may be absent despite meeting laboratory criteria 4

Pathophysiology

The underlying mechanism involves endothelial dysfunction with platelet aggregation leading to microangiopathic changes that specifically target the liver in HELLP syndrome: 6

• Fibrin deposition within hepatic sinusoids causes sinusoidal obstruction and hepatic ischemia 4, 6
• This can progress to subcapsular hematomas, parenchymal hemorrhage, and potentially hepatic rupture 4, 6
• The degree of thrombocytopenia correlates directly with liver dysfunction severity and predicts adverse maternal outcomes 4, 6

Diagnostic Approach

When to Suspect HELLP

65% of symptomatic HELLP patients present with right upper quadrant or epigastric pain, which should immediately trigger laboratory evaluation and imaging: 4

• Abdominal pain or vomiting during the third trimester must prompt consideration of HELLP 2
• New-onset hypertension with any organ dysfunction warrants complete laboratory workup 1

Essential Laboratory Monitoring

LDH and platelet count are the two most important clinical tools for disease assessment: 3

• LDH serves as a dual marker reflecting both hemolysis extent and hepatic dysfunction 6, 3
• AST, ALT, LDH, and total bilirubin are the most useful markers for following disease progression 4
• Platelet count <100,000/mm³ indicates severe thrombocytopenia and active HELLP with significant maternal risk 4

Imaging Requirements

Abdominal ultrasound must be performed if symptoms suggest hepatic complications: 1

• Perform imaging for right upper quadrant pain, epigastric pain, or right shoulder pain 1
• Higher prevalence of hepatic hemorrhage or hematoma occurs with platelet count <20×10⁹/L 1

Management Implications

Why the Distinction Matters Clinically

Recognizing HELLP as severe preeclampsia ensures comprehensive evaluation: 1

• Clinicians must seek all other features of preeclampsia when HELLP is identified 1
• Blood pressure control, seizure prophylaxis, and maternal organ dysfunction assessment are mandatory 1
• The presence of HELLP laboratory findings indicates severe disease requiring prompt delivery after stabilization 1, 4

Definitive Treatment

Prompt delivery is the only definitive treatment once maternal coagulopathy and severe hypertension are corrected: 1, 4

• HELLP syndrome only resolves after delivery 4
• Delayed intervention carries 3.4% maternal mortality risk 4
• Maternal mortality rate ranges from 1.0-24.0% with perinatal mortality of 7.0-70.0% 3

Common Pitfall to Avoid

Never delay delivery waiting for laboratory values to normalize—this is a critical error that increases maternal mortality. 4 The syndrome will not improve until after delivery, and expectant management beyond stabilization (except in select cases <34 weeks with stable maternal condition) worsens outcomes. 4