Is it safe to withhold convulsion prophylaxis in preeclamptic women without neurological features?

Objective: To determine the incidence of eclampsia (seizures) among preeclamptic women in whom convulsion prophylaxis is withheld. Methods: A retrospective analysis of prospectively gathered data on maternal and fetal outcomes of 1099 preeclamptic women referred for joint physician and obstetrician care between 1987 and 1995. All patients were managed according to a uniform departmental protocol for management of hypertensive pregnancies. Convulsion prophylaxis (intravenous followed by oral phenytoin until 5 days postpartum) was recommended if a preeclamptic woman had features suggesting central nervous system involvement, namely hyperreflexia with clonus, severe headaches with hyperreflexia, or repeated visual scotomata. Preeclamptic women without these features were not recommended for convulsion prophylaxis. Main Outcome Measure: Eclampsia (convulsions). Results: Eclampsia occurred in four women, none of whom had received convulsion prophylaxis. This was the initial presentation for two of these women and neither of the others had features suggesting central nervous system involvement prior to their seizure. All women and three of four babies survived. One hundred forty (13%) received phenytoin and none convulsed. The risk of eclampsia in preeclamptic women judged not to require convulsion prophylaxis was 0.2%, or 0.6% when only proteinuric preeclampsia was considered. Conclusion: There is only a small risk of eclampsia if convulsion prophylaxis is withheld in preeclamptic women (managed in a modern obstetric unit) who do not have features of central nervous system involvement.