Fetal acoustic stimulation testing. III. Predictive value of a reactive test.

The nonstress test (NST) is a helpful adjunct to the management of high-risk pregnancies. However, fetal sleep states may lead to falsely nonreactive tests. We assessed the usefulness of transabdominal acoustic stimulation of the fetus and demonstrated an approximately 50% reduction in the number of nonreactive tests and a shorter testing time. No change in the predictive reliability of a reactive test was observed. With regard to the intrapartum and neonatal outcome in women delivering within seven days of a reactive test, no difference between the incidence of meconium-stained amniotic fluid, depressed one- or five-minute Apgar scores or operative intervention for fetal distress could be identified. A reactive test evoked by acoustic stimulation is as reliable as the NST. It offers the additional benefits of reduced testing time and a lower incidence of nonreactive tests.