Assessing the diagnostic accuracy and efficacy of selected antepartum fetal surveillance techniques

Published studies on the contraction stress test (CST), the nonstress test (NST), and monitoring of fetal movement were reviewed to assess the accuracy and efficacy of these techniques. The false-negativity and false-positivity rates, sensitivity, and specificity of these tests were assessed with use of perinatal mortality and various measures of morbidity as outcomes. Both the CST and the NST generally demonstrated low sensitivity and high rates of false positivity. No randomized controlled trials have been conducted that are of sufficient size to demonstrate whether there is a significant difference in outcome following use of the CST or the NST. A single nonrandomized, controlled trial evaluating fetal-movement monitoring suggested clinical benefit. Direct costs of NSTs and CSTs in the United States were estimated to exceed $200 million per year. Yet the CST and the NST have not been demonstrated to be useful diagnostic tests. The CST, the NST, and fetal-movement monitoring are potentially useful screening tests. However, they require critical evaluation, with large randomized, controlled trials, to determine their efficacy and safety before their further diffusion into obstetrical practice.