HELLP SYNDROME

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"HELLP syndrome"[MeSH Terms] AND management

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HELLP Syndrome

Definition & Acronym

HELLP is an acronym for:
  • H - Hemolysis (microangiopathic hemolytic anemia)
  • EL - Elevated Liver enzymes
  • LP - Low Platelets
It represents a severe form of preeclampsia in which hepatic and hematologic abnormalities dominate, driven by thrombotic microangiopathy (TMA).
  • Harrison's Principles of Internal Medicine 22E, p. 2490
  • Comprehensive Clinical Nephrology 7e, p. 630
  • Brenner and Rector's The Kidney, p. 2028

Epidemiology

StatisticFigure
Incidence in all pregnancies0.2-0.9%
In severe preeclampsia10-20%
Maternal mortality1-7.4% (up to 34% in severe cases)
Perinatal mortality7-34% (depends on gestational age)
Cases before week 28~20%
Postpartum onset~30% of cases
Risk factors: Advanced maternal age, Caucasian ethnicity, multiparity, abnormal placentation, family history, elevated fetal mRNA for FLT1/endoglin. Patients with antiphospholipid syndrome have elevated risk.
Importantly, ~20% of cases have NO preceding hypertension or proteinuria, making it a diagnostic trap.

Pathophysiology

The exact cause is unknown, but the central mechanism involves:
  1. Abnormal placentation → systemic endothelial dysfunction
  2. Activation of the coagulation cascade → fibrin deposition in hepatic sinusoids and microvasculature
  3. Microangiopathic hemolytic anemia → platelet consumption and red cell fragmentation (schistocytes)
  4. Hepatic ischemia → from sinusoidal fibrin deposition and intravascular hypovolemia → elevated transaminases
  5. Complement dysregulation - complement gene mutations or dysfunction found in 30-40% of HELLP patients
  6. Elevated inflammatory markers (CRP, IL-1Ra, IL-6) and soluble HLA-DR compared to preeclampsia alone

Clinical Features

Symptom/SignNotes
Epigastric / RUQ painMost common presenting symptom - can mimic gastroenteritis, cholecystitis, pancreatitis
Nausea & vomitingFrequent accompanying feature
MalaiseMay mimic viral syndrome
Headache, blurred visionSigns of CNS involvement
HypertensionMay be absent initially or at all
ProteinuriaPresent in 86-100% overall, but may be absent
Key pitfall: Hypertension may be absent, leading to misdiagnosis as gastroenteritis, cholecystitis, hepatitis, or pyelonephritis. Any pregnant woman at >20 weeks gestation (or up to 7 days postpartum) with abdominal pain must be evaluated for HELLP.
  • Tintinalli's Emergency Medicine, p. 674

Diagnostic Criteria

ACOG Task Force Criteria (current standard)

  1. Hemolysis PLUS at least 2 of the following:
    • Thrombocytopenia (platelets <100,000/μL)
    • Renal insufficiency (creatinine >1.1 mg/dL or doubling)
    • Impaired liver function (transaminases twice upper limit of normal)
    • Pulmonary edema
    • New-onset headache unresponsive to medication, or visual symptoms

Key Lab Findings

TestFinding in HELLP
Peripheral smearSchistocytes (fragmented RBCs)
Platelet count<100,000/μL (<150,000 suspicious)
LDH>600 U/L
AST/ALTElevated (usually <500 U/L, rarely up to >1000 U/L)
Total bilirubin>1.2 mg/dL
Serum haptoglobinLow (hemolysis marker)
Urine proteinProteinuria (86-100%)

Classification Systems

Mississippi Triple-Class System (platelet-based severity)

ClassPlatelet Nadir
Class I (Severe)≤50,000/mm³
Class II (Moderate)50,001-100,000/mm³
Class III (Mild)100,001-150,000/mm³

Tennessee Classification

  • Complete HELLP: All 3 criteria present (hemolysis + elevated LDH/AST + platelets <100,000)
  • Incomplete (Partial) HELLP: Only 1 or 2 criteria present (e.g., EL only, LP only, HEL without thrombocytopenia)
  • Sleisenger & Fordtran's GI and Liver Disease, p. 4067
  • Yamada's Textbook of Gastroenterology 7e

Complications

Maternal

ComplicationApproximate Rate
Eclampsia6%
Placental abruption10%
DIC8-21%
Acute renal failure5-50%
Pulmonary edema10%
Hepatic subcapsular hematoma/rupture~1% of HELLP cases
Cerebral infarction/hemorrhageRare but life-threatening
Purtscher-like retinopathyRare (hemorrhagic/vaso-occlusive)
Liver rupture occurs predominantly in the right lobe, following subcapsular hemorrhage stretching the hepatic capsule. More than 95% of liver ruptures in pregnancy involve severe preeclampsia/HELLP. The triad of RUQ pain + hypertension + shock should raise immediate suspicion.

Fetal

  • Preterm birth
  • IUGR (fetal growth restriction)
  • Fetal demise

Differential Diagnosis

The table below summarizes the key distinctions from overlapping conditions:
FeatureHUS/TTPHELLPAFLP
Hemolytic anemia+++++±
Thrombocytopenia+++++±
Coagulopathy-±+
CNS symptoms++±±
Renal failure++++++
Hypertension±+++±
Elevated AST±+++++
Elevated bilirubin++++++
Serum ammoniaNormalNormalHigh
Effect of deliveryNoneRecoveryRecovery
ADAMTS13<10% (TTP)30-60% reducedNormal
ManagementPlasma exchangeSupportive + deliverySupportive + delivery
LDH:AST ratio can help: ratio ~13:1 in HELLP with preeclampsia vs. ~29:1 in non-preeclamptic patients.
  • Brenner and Rector's The Kidney, p. 2034-2036
  • Harrison's 22E

Management

1. Immediate Stabilization

  • IV access, blood products on standby
  • Continuous fetal monitoring
  • Seizure prophylaxis: Magnesium sulfate (4 g IV loading dose, then 1-2 g/hr infusion)
  • Antihypertensives for BP ≥160/110 mmHg:
DrugMechanismOnsetDosage
Labetalolα + β blocker5 min20 mg IV, then 40-80 mg q10 min (max 300 mg)
HydralazineArterial vasodilator20 min5 mg IV or 10 mg IM, repeat q20 min
NifedipineCalcium channel blocker10-20 min10 mg PO, repeat in 30 min

2. Delivery - The Definitive Treatment

  • The key treatment is delivery; HELLP syndrome resolves spontaneously after delivery
  • Gestational age ≥34 weeks: Prompt delivery recommended
  • <34 weeks, no serious complications: Consider antenatal corticosteroids (betamethasone) for fetal lung maturity FIRST, then deliver
  • Serious maternal/fetal complications: Prompt delivery regardless of gestational age
  • Cesarean section: Consider platelet transfusion to 40,000-50,000 cells/μL before procedure

3. Platelet Transfusion

  • Indicated for platelets <40,000-50,000/μL, especially pre-operatively

4. Corticosteroids (controversial)

  • Dexamethasone IV has been used in some protocols to accelerate recovery of platelets and transaminases, especially postpartum - but evidence is mixed and this is NOT routinely recommended per some guidelines

5. Plasma Exchange

  • No proven benefit in HELLP
  • May be indicated if TTP has not been ruled out
  • Eculizumab (anti-C5 complement inhibitor) has been reported in small case series if complement-mediated aHUS is suspected

6. Postpartum Monitoring

  • Labs may worsen before improving after delivery
  • Resolution typically within 48-72 hours, complete by 5 days
  • Monitor up to 7 days postpartum since 20-30% develop HELLP after delivery

Prognosis & Recurrence

  • Maternal mortality: ~1% (with modern care), perinatal mortality 7-34%
  • HELLP usually resolves fully after delivery
  • Recurrence risk in future pregnancies: reported at ~3-27%
  • Patients with complement mutations (30-40% of HELLP) may be at elevated risk of aHUS in future pregnancies

Summary Mnemonic

HELLP = Think whenever a pregnant woman >20 weeks presents with:
  • Headache + Epigastric pain + Low platelets + Liver enzymes up + Proteinuria
Sources: Harrison's Principles of Internal Medicine 22E | Brenner & Rector's The Kidney | Tintinalli's Emergency Medicine | Sleisenger & Fordtran's GI and Liver Disease | Yamada's Textbook of Gastroenterology 7e | Comprehensive Clinical Nephrology 7e | Creasy & Resnik's Maternal-Fetal Medicine | Textbook of Family Medicine 9e
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