Antepartum fetal heart rate testing. II. Intrapartum fetal heart rate observation and newborn outcome following a positive contraction stress test.

The positive contraction stress test (CST) has been looked upon as a predictor of fetal compromise. On this basis, some reports advise routine cesarean delivery on the assumption that the compromised fetus should not tolerate labor. Other authors advocate selective cesarean delivery, based on obstetrical factors such as the inducibility of the cervix and the practicality of fetal monitoring. Finally, an attempted trial of labor may be allowed on the basis of occurrence of fetal heart rate acceleration with fetal movement, or "reactivity." The occurrence of "false positive" tests is not infrequent (20 to 45 per cent). The definition of such is unclear and little quantitative information regarding intrapartum performance is available. In this series of 27 patients, a trial of labor was undertaken in 20. Vaginal delivery occurred in 11 (55 per cent) and cesarean section in nine (45 per cent). Fetal heart rate abnormalities thought to indicate "distress" occurred in five patients (25 per cent). The "positive" window or repetitive late deceleration as equivalent to the positive CST was seen in only three patients during labor. A trial of labor should be attempted in the face of a positive CST whenever obstetric factors are favorable and careful intrapartum monitoring can be performed.