Key Facts

Eclampsia is defined as the occurrence of one or more generalised tonic-clonic seizures in association with pre-eclampsia. It is a medical emergency with significant maternal and fetal mortality if not promptly managed.

Epidemiology

• Incidence: approximately 1 in 2,000 pregnancies in the UK
• UK maternal mortality from eclampsia/pre-eclampsia: approximately 0.3 per 100,000 maternities
• More common in primigravidae, multiple pregnancies, and extremes of maternal age
• Can occur antepartum (38%), intrapartum (18%), or postpartum (44%)

Aetiology

• Arises from severe pre-eclampsia with cerebral vasospasm and endothelial dysfunction
• Risk factors include: nulliparity, pre-existing hypertension, chronic kidney disease, autoimmune disease (SLE, antiphospholipid syndrome), diabetes, BMI >35, age >40, multiple pregnancy, family history of pre-eclampsia
• Abnormal placentation with defective spiral artery remodelling is the underlying pathological process

Pathophysiology

• Inadequate trophoblastic invasion of spiral arteries leads to placental ischaemia
• Release of anti-angiogenic factors (sFlt-1, soluble endoglin) causes widespread endothelial dysfunction
• Cerebral vasospasm and blood-brain barrier disruption lead to cerebral oedema and seizures
• Posterior reversible encephalopathy syndrome (PRES) is the radiological correlate on MRI

Typical Presentation

• Generalised tonic-clonic seizures in a pregnant or recently delivered woman
• Often preceded by symptoms of severe pre-eclampsia: severe headache, visual disturbance (blurred vision, scotomata, flashing lights), epigastric/right upper quadrant pain
• Hypertension (BP ≥140/90 mmHg) with proteinuria (≥300mg/24h or PCR ≥30mg/mmol)

Prodromal Symptoms

• Severe headache unresponsive to simple analgesia
• Visual disturbance (photopsia, scotomata, cortical blindness)
• Epigastric or right upper quadrant pain (hepatic capsule distension)
• Hyperreflexia and clonus (≥3 beats)
• Rapidly progressive oedema

Red Flags

• Seizures at any point in pregnancy or within 6 weeks postpartum
• Systolic BP >160 mmHg or diastolic >110 mmHg
• HELLP syndrome features (haemolysis, elevated liver enzymes, low platelets)
• Papilloedema
• Signs of placental abruption
• Oliguria (<0.5 mL/kg/hr)
• Glasgow Coma Scale <14

Bedside

• Blood pressure monitoring (every 15 minutes during acute phase)
• Urinalysis (proteinuria quantification - PCR or 24h collection)
• Continuous CTG for fetal monitoring
• Fluid balance chart (strict input/output)
• Capillary blood glucose

Bloods

• FBC (particularly platelet count - <100 × 10⁹/L suggests HELLP)
• U&Es (renal function - uric acid, creatinine)
• LFTs (ALT/AST elevation suggests HELLP)
• Coagulation screen (DIC screen)
• Blood film (for fragmented red cells/schistocytes)
• Group and save / crossmatch
• Serum magnesium levels (therapeutic range 2-4 mmol/L)

Imaging

• CT head if atypical features or prolonged post-ictal state
• MRI brain if suspecting PRES or other intracranial pathology
• Ultrasound for fetal assessment (growth, liquor volume, Dopplers)

Special Tests

• PlGF-based testing if <37 weeks (NICE NG133)
• Urine protein:creatinine ratio
• Arterial blood gas if respiratory compromise

Non-pharmacological

• Multidisciplinary approach: obstetrics, anaesthetics, midwifery, neonatology
• Left lateral position during seizure
• Airway management and high-flow oxygen
• Monitor in high-dependency setting
• Strict fluid balance (limit IV fluids to 80 mL/hr to reduce pulmonary oedema risk)

Pharmacological

• Magnesium sulphate: 4g IV loading dose over 5-15 minutes, followed by 1g/hr infusion for 24 hours (MAGPIE trial evidence)
• Recurrent seizures: further 2g IV magnesium sulphate bolus
• Antihypertensives: Labetalol 200mg PO or 50mg IV (first-line per NICE NG133); nifedipine 10-20mg PO (second-line); hydralazine 5mg IV (third-line)
• Target BP <150/100 mmHg
• Antidote for magnesium toxicity: calcium gluconate 10% 10 mL IV over 10 minutes

Surgical/Interventional

• Delivery is the definitive treatment
• If ≥34 weeks: plan delivery within 24-48 hours
• If <34 weeks: consider corticosteroids (betamethasone 12mg IM × 2 doses, 24h apart) for fetal lung maturation if delivery can be safely delayed
• Emergency caesarean section if maternal or fetal compromise

Referral Criteria

• All cases require consultant obstetrician and anaesthetist involvement
• HDU/ITU admission for ventilatory support or multi-organ failure
• Follow-up at 6-8 weeks postpartum with BP and proteinuria check
• Referral to specialist hypertension clinic if persistent hypertension

• UK maternal mortality from eclampsia: approximately 1-2% (has fallen with improved management)
• Perinatal mortality: 5-12% (higher with preterm delivery)
• 35% of women develop complications: HELLP syndrome, DIC, renal failure, pulmonary oedema, ARDS
• Risk of recurrence in subsequent pregnancy: 2-5% for eclampsia, 15-25% for pre-eclampsia
• Long-term cardiovascular risk is increased: 2-4× risk of chronic hypertension, 2× risk of ischaemic heart disease
• Aspirin 75-150mg from 12 weeks in subsequent pregnancies reduces pre-eclampsia risk by 17% (NICE NG133)

MAGPIE Trial Summary

Severity Classification

Magnesium Sulphate Monitoring