The significance of single sporadic deceleration during a nonstress test

Abstract

The significance of single sporadic deceleration occurring during antepartum fetal heart rate monitoring was assessed. Single sporadic deceleration was defined as a drop of fetal heart rate of at least 40 bpm below baseline lasting for at least 2 min. During the year 1980, 7202 nonstress tests (NST) were performed in pregnant patients, with gestational ages ranging from 32–42 wk. Among these, 62 cases of single sporadic deceleration were observed. In 48 of these cases the single sporadic deceleration was followed by a normal reactive NST. In 14 patients NST following the single sporadic deceleration was non-reactive. In those cases oxytocin challenge test (OCT) was performed and was negative in 10 and positive in 4 cases. In the latter 4 patients labor was induced and all required cesarean section because of severe fetal distress. The remaining 58 women were followed up at the High-Risk Pregnancy Unit until spontaneous labor began, their deliveries were monitored throughout. In 8 cases out of the 58, fetal distress was observed during labor and in 4 of them cesarean section was required. The occurrence of single sporadic deceleration at gestational ages 32–42 wk is not an alarming sign providing the NST and/or O.C.T. are normal. However, the incidence of fetal distress during labor is significantly higher in fetuses with single sporadic deceleration as compared to the normal parturient population.