The nonstress test: a review of 3,000 tests

Abstract

For the antepartum evaluation of fetal well-being in the high-risk pregnancy, the nonstress test (NST) has been found to be clinically efficacious. The basis for its interpretation has been the presence (reactive or normal) or absence (nonreactive or abnormal) of fetal heart rate accelerations in response to fetal activity. If a nonreactive NST was encountered, the fetus was evaluated further with the contraction stress test (CST). Between July 5, 1977, and October 20, 1979, 3,000 NSTs were performed on 1,452 women with high-risk pregnancies. The NST interpretations were reactive (85.4%), nonreactive (14.0%), and unsatisfactory (0.6%). While the reactive group experienced a favorable fetal outcome, the nonreactive group demonstrated a significant increase in the overall cesarean section rate, the rate of cesarean sections for fetal distress, and the perinatal mortality rate. Based on our experience, the NST continues to be a valuable procedure for the assessment of fetal well-being in our high-risk pregnancies.