Multiple assessment techniques evaluate antepartum fetal risks.

Abstract

As technology has advanced, the field of antepartum fetal evaluation has grown. As reviewed here, a variety of options are available for use in the complicated pregnancy, including application of fetal heart rate monitoring techniques, noninvasive assessment of amniotic fluid volume, sonographic evaluation of fetal behavior, and Doppler assessment of fetal blood flow. It remains unclear which test is the best for any particular situation. The NST is the simplest test to perform but has a higher false-positive rate than the biophysical profile or the CST. These two tests also appear to demonstrate superior sensitivity, at the expense of increased testing time and cost. The application of vibroacoustic stimulation improves the specificity of the NST, while the addition of a sonographic assessment of amniotic fluid volume increases sensitivity and creates an acceptable alternative as a primary test. The limited biophysical profile, with the NST component initially omitted, provides some savings in time and cost without apparent loss of sensitivity or specificity when compared with the full profile. Ultimately, while one particular technique of fetal assessment may never prove to be the best, certain techniques may have advantages over others in particular clinical situations. Umbilical artery Doppler velocimetry appears to be a useful adjunct to other forms of testing, especially in the pregnancy at risk for intrauterine growth restriction and pre-eclampsia. Recent data have shown the biophysical profile predicts the onset of amnionitis in the setting of preterm premature rupture of membranes (PROM). The sonographic assessment of amniotic fluid volume is particularly important in the serial evaluation of the pregnancy complicated by fetal growth restriction. As new technology leads to innovative forms of testing, it is expected that these new tests of fetal status will similarly add to, rather than replace, the existing items in our armamentarium.