Contents
Overview
HELLP syndrome is characterised by haemolysis, elevated liver enzymes, and thrombocytopenia. It complicates approximately 0.5–0.9% of all pregnancies and occurs in 10–20% of cases of severe pre-eclampsia. It is associated with significant maternal and perinatal mortality. Delivery is the only definitive treatment.
Most cases occur in the third trimester, but HELLP may develop postpartum, typically within 48 hours of delivery.
Pathophysiology
HELLP syndrome is considered a severe manifestation of pre-eclampsia, sharing its underlying pathophysiology: abnormal placentation leads to poor trophoblast invasion and high-resistance uteroplacental blood flow. Placental hypoxia triggers the release of antiangiogenic factors — soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin — which cause systemic maternal endothelial dysfunction.
Endothelial injury activates platelets and the coagulation cascade, producing microvascular fibrin deposition. Erythrocytes fragment as they traverse these fibrin strands — microangiopathic haemolytic anaemia (MAHA). The liver is particularly susceptible: sinusoidal fibrin deposition causes hepatocellular ischaemia, necrosis, and elevation of liver enzymes. Hepatic capsule distension produces the characteristic right upper quadrant pain.
Clinical Features
HELLP may present insidiously. Common symptoms include:
- Right upper quadrant or epigastric pain (80%)
- Nausea and vomiting
- Malaise and headache
- Hypertension — present in the majority but absent in up to 20% (normotensive HELLP)
Progression to complications can be rapid:
- Eclampsia (seizures)
- DIC (in 20% of cases)
- Hepatic haematoma or rupture
- Acute kidney injury (10–15%)
- Placental abruption
- Pulmonary oedema (secondary to low oncotic pressure, fluid shifts, cardiac dysfunction)
Diagnosis
The Tennessee classification requires all three criteria to be present for the diagnosis:
| Criterion | Threshold |
|---|---|
| Haemolysis | Abnormal blood film (schistocytes) AND LDH >600 IU/L AND bilirubin >20 µmol/L |
| Elevated liver enzymes | AST or ALT >70 IU/L |
| Low platelets | Platelets <100 × 10⁹/L |
Partial HELLP describes cases where one or two criteria are met; management is guided by clinical severity rather than strict diagnostic category.
The Mississippi triple-class system further stratifies by platelet nadir, which correlates with complication risk.
Management
Delivery
Delivery is the definitive treatment. The timing depends on gestational age and clinical severity:
≥34 weeks gestation: Prompt delivery is recommended. Mode of delivery depends on obstetric factors (cervical favourability, fetal position, urgency).
<34 weeks: Corticosteroids (betamethasone 12 mg IM, two doses 24 hours apart) are given for fetal lung maturation if delivery is not immediately required. A period of stabilisation and monitoring of 24–48 hours may be appropriate in a stable patient, but deteriorating maternal condition or fetal compromise mandates immediate delivery.
<28 weeks: The decision is particularly complex and requires senior obstetric, neonatal, and critical care input.
Antihypertensive Therapy
The immediate target is to reduce systolic blood pressure below 160 mmHg to reduce the risk of maternal intracranial haemorrhage.
Options:
- Labetalol IV (first line in the UK) — 50 mg IV bolus, then infusion
- Hydralazine IV — 5 mg bolus, repeat every 20 minutes
- Nifedipine oral (modified release) — effective for less acute hypertension
Avoid ACE inhibitors and ARBs in pregnancy.
Magnesium Sulphate
Magnesium sulphate reduces the risk of eclampsia in severe pre-eclampsia and HELLP and is the treatment of choice for established eclamptic seizures.
Loading dose: 4 g IV over 5–10 minutes.
Maintenance: 1 g/hour infusion for 24 hours.
Monitor for toxicity: loss of deep tendon reflexes (Mg 2.5–5 mmol/L), respiratory depression (>5 mmol/L), cardiac arrest (>7.5 mmol/L). Antidote: calcium gluconate 10 mL of 10% solution IV.
Blood Products
- Platelet transfusion: threshold <20 × 10⁹/L without bleeding, <50 × 10⁹/L prior to caesarean section, or <75 × 10⁹/L prior to general anaesthesia with anticipated significant blood loss
- FFP and cryoprecipitate if concurrent DIC
- Packed red cells for haemolysis-related anaemia
ICU Care
ICU admission is appropriate for:
- Eclampsia or altered consciousness
- Pulmonary oedema requiring ventilatory support
- Severe DIC
- Hepatic haematoma or impending rupture
- Renal failure requiring renal replacement therapy
- Haemodynamic instability
Fluid management requires careful balance: oncotic pressure is low, and excessive fluid increases the risk of pulmonary oedema. Invasive monitoring may be required.
Complications
Hepatic haematoma: Subcapsular haematoma may be detected on ultrasound or CT in patients with severe right upper quadrant pain or worsening liver tests. Conservative management if haemodynamically stable. Rupture causes haemoperitoneum and requires emergency surgical or interventional radiology input.
Eclampsia: Generalised tonic-clonic seizures, managed with magnesium and airway protection.
DIC: Managed with blood product replacement. Triggers include hepatic necrosis and placental abruption.
Postpartum haemorrhage: Compounded by thrombocytopenia and coagulopathy. Requires obstetric and haematology input.
AKI: Usually resolves with delivery. RRT may be required in severe cases.
Viva Questions
What are the diagnostic criteria for HELLP syndrome?
HELLP syndrome is diagnosed by the Tennessee criteria: haemolysis evidenced by an abnormal blood film with schistocytes, LDH above 600 IU/L, and bilirubin above 20 µmol/L; elevated liver enzymes with AST or ALT above 70 IU/L; and thrombocytopenia with a platelet count below 100 × 10⁹/L. All three criteria must be present for the complete syndrome. Hypertension is present in the majority of patients but is not part of the diagnostic criteria — normotensive HELLP occurs in up to 20% of cases and may be overlooked as a result. The differential diagnosis includes TTP and HUS, both of which cause MAHA and thrombocytopenia; a key distinguishing feature is that TTP and HUS are not gestational conditions and do not resolve with delivery.
How does the management differ depending on gestational age?
The gestational age at presentation fundamentally changes the management approach because delivery is the only definitive treatment but prematurity carries its own risks. At 34 weeks or beyond, prompt delivery is recommended: the risks of continued pregnancy outweigh the risks of late preterm birth. Between 28 and 34 weeks, a short period of stabilisation — typically 24–48 hours — may be justified in a stable patient to allow administration of antenatal corticosteroids for fetal lung maturation and to organise neonatal care. Deterioration in maternal condition (worsening thrombocytopenia, hepatic haematoma, DIC, refractory hypertension, eclampsia) mandates immediate delivery regardless of gestational age. Below 28 weeks, the clinical situation is most complex: the prognosis for a very preterm infant must be carefully weighed against the maternal risks of continuing a pregnancy with severe HELLP, and the decision requires senior multidisciplinary input. Throughout all gestational ages, magnesium sulphate and antihypertensive therapy should be initiated as soon as the diagnosis is made.
What are the serious complications of HELLP and how are they managed in the ICU?
The most immediately life-threatening complications are hepatic rupture, eclampsia with status epilepticus, DIC, and pulmonary oedema. Hepatic haematoma presents with worsening right upper quadrant pain, a falling haematocrit, and may be visible on CT or ultrasound. If contained, conservative management with close monitoring may be appropriate; rupture causing haemoperitoneum requires emergency surgery or interventional radiology with hepatic artery embolisation. Eclampsia is treated with magnesium sulphate (4 g IV loading dose) and, if the patient cannot protect her airway, rapid sequence intubation. DIC is managed by treating the underlying cause (delivery) and by blood product replacement — guided by coagulation results and clinical bleeding. Pulmonary oedema must be managed conservatively with fluid restriction and diuresis; excessive fluid administration in the context of low oncotic pressure worsens pulmonary function and should be avoided. Invasive haemodynamic monitoring guides fluid balance in severe cases.