What is the difference between atypical Hemolysis, Elevated Liver enzymes, and Low Platelet count (HELLP) Syndrome and partial HELLP Syndrome in pregnant women?

Difference Between Atypical HELLP Syndrome and Partial HELLP Syndrome

Partial HELLP syndrome refers to the presence of only one or two components of the classic diagnostic triad (hemolysis, elevated liver enzymes, low platelets), while atypical HELLP syndrome is not a formally recognized clinical entity in current guidelines—the term "atypical" typically describes unusual presentations or timing of complete or partial HELLP syndrome.

Partial HELLP Syndrome: Definition and Diagnostic Criteria

Partial HELLP syndrome occurs when a pregnant woman presents with incomplete fulfillment of the diagnostic triad, meaning she may have:

• Elevated liver enzymes (AST >200 U/L or ALT >159 U/L) plus thrombocytopenia (<100,000/mm³) without hemolysis 1
• Hemolysis (schistocytes on peripheral smear, elevated LDH >295 U/L, elevated indirect bilirubin) plus elevated liver enzymes without thrombocytopenia 1, 2
• Hemolysis plus thrombocytopenia without significantly elevated liver enzymes 3

The Tennessee Classification System requires all three components for complete HELLP syndrome: hemolysis with increased LDH (>600 U/L), AST (≥70 U/L), and platelets <100 × 10⁹/L 2. When only one or two of these criteria are met, the diagnosis is partial HELLP syndrome 4, 3.

Clinical Significance of Partial HELLP Syndrome

Partial HELLP syndrome represents a progressive condition that may evolve into complete HELLP syndrome, requiring close surveillance:

• Laboratory monitoring should occur every 6-12 hours to detect progression to complete syndrome 5
• Recent studies suggest some women with partial HELLP syndrome may be candidates for expectant management or corticosteroid therapy in selected cases before 34 weeks' gestation 3
• The syndrome remains associated with increased maternal and fetal risk, though potentially less severe than complete HELLP 3

"Atypical" HELLP Syndrome: Understanding the Terminology

The term "atypical HELLP syndrome" is not a standardized diagnostic category in current guidelines 6, 7, 5, 1. When clinicians use this term, they typically refer to:

Atypical Timing

• Postpartum presentation: 30% of HELLP cases occur or worsen postpartum, with 20% occurring within 48 hours of delivery 6, 5
• Early gestational age presentation (before 27 weeks) 2

Atypical Clinical Features

• Absence of hypertension: HELLP syndrome can occur in patients with normal blood pressure in 15% of cases 6
• Absence of proteinuria despite meeting laboratory criteria 6
• Asymptomatic presentation: patients may present without the classic symptoms of right upper quadrant pain, nausea, or headache 6

Atypical Laboratory Patterns

• Normal prothrombin time and fibrinogen levels despite other HELLP criteria being met 1
• Mild thrombocytopenia (platelets 50,000-100,000/mm³) with pronounced hemolysis and liver enzyme elevation 5

Critical Management Distinctions

Both partial and atypically presenting HELLP syndrome require the same aggressive approach as complete HELLP syndrome once diagnosed:

• Immediate maternal stabilization with magnesium sulfate for seizure prophylaxis 5
• Abdominal imaging (ultrasound or CT) to rule out hepatic hemorrhage, infarct, or rupture 6, 5
• Prompt delivery after maternal stabilization if ≥34 weeks' gestation or if maternal/fetal condition deteriorates 5, 2
• Transfer to ICU or high-dependency unit for continuous monitoring 5

Common Pitfalls to Avoid

Do not delay intervention waiting for "complete" HELLP syndrome to develop:

• Partial HELLP syndrome is a progressive condition that can rapidly deteriorate 4, 2
• The presence of any two components of the triad warrants intensive monitoring and preparation for delivery 3
• Delaying delivery waiting for laboratory values to normalize increases maternal mortality risk to 3.4% 5

Do not dismiss the diagnosis based on absence of hypertension or proteinuria:

• 15% of HELLP cases occur with normal blood pressure 6
• The diagnosis is primarily laboratory-based, not dependent on classic preeclampsia features 6, 3

Do not use regional anesthesia if platelets <100,000/mm³ or elevated INR, regardless of whether HELLP is "complete" or "partial," due to epidural hematoma risk 5.