The significance of single sporadic deceleration during a nonstress test

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.