Eclampsia is a seizure that can occur as a complication of pregnancy, following pre-eclampsia. Pre-eclampsia describes the high blood pressure and rapid weight gain that can occur in pregnancy. Eclampsia seizures are tonic-clonic in nature and can become life-threatening unless quickly and properly treated. Together, pre-eclampsia and eclampsia are referred to as hypertensive disorder of pregnancy.
Features and causes of eclampsia
The main feature of eclampsia is a seizure that is not linked to any pre-existing disorder. Women who already have an underlying vascular disorder such as diabetes, high blood pressure or kidney disease are at a greater risk of developing eclampsia and pre-eclampsia than women without these conditions. Other conditions that increase the risk include thrombophilic diseases such as antiphospholipid syndrome. In addition, women who are over 40 years of age or women with twin or multiple pregnancies are also at a greater risk of eclampsia. A family history of the condition can also increase the risk.
Pathology of eclampsia
Pre-eclampsia (and therefore eclampsia) is thought to be caused by the abnormal development of the placenta due to problems with the vasculature that supplies it. In cases of severe pre-eclampsia, the only way to prevent eclampsia is for the baby to be delivered. Continuing the pregnancy in cases of sever pre-eclampsia is dangerous to both the mother and the baby.
Biological markers have been associated with eclampsia. For example, a blood vessel dilator called adrenomedullin has been shown to be reduced in women with pre-eclampsia and eclampsia. Other agents that act on the blood vessels in hypertensive disorders of pregnancy include nitric oxide, prostacyclin, thromboxane A2 and endothelins.
Eclampsia is a form of hypertensive encephalopathy, a cerebral condition caused by a sustained and severe elevation in blood pressure. The blood flow to the brain is increased and abnormal endothelial function can lead to the development of cerebral edema and intracranial bleeding or hemorrhage.
Detection and management
Pregnant women are regularly monitored for pre-eclampsia, which can be detected by checking blood pressure and urinary protein markers throughout the pregnancy. Women who develop pre-eclampsia are closely monitored until their baby can be delivered. The mother may be given antihypertensive medications until it is possible for the baby to be delivered, which is usually at a round 37 to 38 weeks, but can be earlier in severe cases.
Reviewed by Sally Robertson, BSc