Eclampsia: Definition and Clinical Features
Eclampsia is the occurrence of new-onset grand mal (tonic-clonic) seizures in a woman with preeclampsia, representing a life-threatening progression of hypertensive disease in pregnancy. 1, 2
Core Diagnostic Criteria
Eclampsia is diagnosed when seizures occur in the setting of preeclampsia, defined as:
- New-onset hypertension (systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg) developing after 20 weeks' gestation 1
- Plus seizure activity that cannot be attributed to other neurological conditions 2, 3
- Proteinuria (≥0.3 g/24 hours or albumin-to-creatinine ratio ≥30 mg/mmol) is often present but not required for diagnosis 1
Timing of Presentation
Eclampsia can occur at three distinct time points:
- Antepartum: Most common presentation, occurring during pregnancy 3
- Intrapartum: During labor and delivery 3
- Postpartum: Within 48 hours after delivery in most cases, but can occur as late as 1 month postpartum (late postpartum eclampsia) 3, 4
Clinical Features and Warning Signs
Neurological Manifestations
- Severe headache unresponsive to analgesics 1, 5
- Visual disturbances including scotomata (blind spots), blurred vision, or occipital lobe blindness 1
- Hyperreflexia and clonus indicating central nervous system irritability 1
- Altered mental status or confusion 4
Systemic Features
- Right upper quadrant or epigastric pain due to liver capsule distension from edema and potential hemorrhage 1, 6
- Severe hypertension (BP ≥160/110 mmHg) 1
- Edema (though no longer part of diagnostic criteria as it occurs in 60% of normal pregnancies) 1
Associated Complications
Maternal Risks
- Cerebrovascular accident (stroke) from uncontrolled hypertension 1
- Pulmonary edema 7
- Acute kidney injury 1, 7
- Hepatic failure or rupture 7
- Disseminated intravascular coagulation 1, 7
- Placental abruption 1, 7
- HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) occurring in conjunction with eclampsia 1
Fetal Risks
- Intrauterine growth restriction 1, 8
- Prematurity from indicated preterm delivery 1, 8
- Intrauterine fetal death 1
- Placental insufficiency 1
Pathophysiology
The underlying mechanism involves:
- Abnormal placentation leading to placental insufficiency 8
- Endothelial dysfunction with release of antiangiogenic factors (particularly sFlt-1) 3, 8
- Cerebral edema and vasogenic changes causing seizure activity 3
- Poor organ perfusion affecting multiple organ systems 1
Epidemiology and Risk Factors
- Affects 5-10% of pregnancies when considering all hypertensive disorders 1, 2
- Preeclampsia complicates 5-7% of pregnancies overall, with 25% risk in women with pre-existing hypertension 1
- Higher risk in first pregnancies, multiple gestations, hydatidiform mole, or diabetes 1
- 10% of maternal deaths from hypertensive disorders occur postpartum 1
Critical Clinical Pitfall
Do not wait for proteinuria to diagnose preeclampsia or eclampsia. The International Society for the Study of Hypertension in Pregnancy now defines preeclampsia as gestational hypertension with evidence of maternal organ dysfunction (renal, hepatic, neurological, or hematological complications) or uteroplacental dysfunction, even without proteinuria. 1 Seizures in the setting of new-onset hypertension after 20 weeks with any organ dysfunction constitute eclampsia. 1