Clinical study on detecting false non-reactive of non-stress test by improved acoustic stimulation

Purpose To approach the clinical significance on detecting false non-reactive of non-stress test (NST) by improved acoustic stimulation. Method One-hundred and sixteen pregnant women who were at 34–41 weeks’ gestation were monitored for the fetal movement and the fetal heart rate. Then, the improved acoustic stimulation which was caused by clapping hands about 1 cm above maternal abdomen over the fetal vertex was given to the pregnant women whose NST were non-reactive. Results Among the 485 NST tests, 143 were non-reactive, accounting for 29.5%. With improved acoustic stimulation, 132 of them turned to be reactive, accounting for 92.3%. With oxygen therapy, 5 of the 11 changed to be reactive, but the other six pregnant women were given emergency caesarean section, and three of them were fetal distress. Among the 110 reactive pregnant women, only two were fetal distress. The sensitivity, specificity, positive, and negative predictive values for predicting fetal distress of NST with improved acoustic stimulation were 60.0, 97.3, 50.0, and 98.2%, respectively. Conclusion NST with improved acoustic stimulation is a convenient, fast, safe, and effective method on detecting false non-reactive NST and it can increase the specificity of NST.