Usefulness of stress-free test in preeclampsia

Poor perinatal outcome in patients with preeclampsia has been reported. This significant risk reinforces the importance of fetal evaluation. The purpose of this study was to evaluate the utility of the nonstress test (NST) in preeclampsia. Criteria for inclusion in this report comprised pregnancies complicated by preeclampsia of longer than 28 weeks of gestation delivered 24 hours of final NST. The study population were divided into mild and severe preeclampsia. Each of the latter two groups was further subdivided into three subgroups by gestational age at 28-31, 32-34 and > 35 weeks. Measurements of adverse perinatal outcome included meconium staining, oligohydramnios, five-minute Apgar score less than 7 beyond 34 weeks of gestational age, intrauterine growth retardation, and perinatal death. A total of 250 patients with preeclampsia were analyzed, among these 147 with mild and 103 with severe disease. There were no stillbirths. Sensitivity of the NST was low ranged from 39% (mild preeclampsia) to 63% (severe disease). Its positive predictive value was equally low (66 and 45%) respectively. Specificity was quite high in both groups (89 and 64%). Its negative predictive value was 73% for mild disease and 78% for severe preeclampsia. The NST is an important test in antepartum care but based on its low sensitivity should not be considered as a stand alone test.