Can fetal biophysical observations anticipate outcome in preterm labor or preterm rupture of membranes?

OBJECTIVE

To evaluate fetal biophysical testing as a predictor of preterm delivery after preterm labor or preterm rupture of the membranes (PROM).

METHODS

We studied 50 women with suspected preterm labor and intact membranes and 25 women with PROM but not in labor between 28 and 36 weeks' gestation. Before treatment, each subject had cervical Bishop scoring and 1-hour ultrasound observation of fetal heart rate, breathing, body movements, and flexion-extensions. Data were compared with t tests, chi 2 tests, or receiver operating curves.

RESULTS

The mean gestational age at entry was similar in both groups. Twenty (80%) PROM and ten (18%) preterm labor patients delivered within 72 hours of admission; two (8%) PROM and 38 (76%) preterm labor patients delivered more than 7 days after admission. Absent breathing and body movements had high positive predictive values (100%) but moderate sensitivities (less than 55%) for predicting delivery within 72 hours or 7 days in the PROM and preterm labor groups. These sensitivities increased to nearly 70% with the addition of Bishop scores. The optimal diagnostic cutoffs for delivery within 72 hours or 7 days were a breathing incidence below 1% for the PROM group and a body movement incidence below 1% for the preterm labor group, and a breathing incidence of at most 5%.

CONCLUSIONS

Complete absence of one biophysical variable confers limited sensitivity but high positive predictive value for early delivery in patients with preterm labor or PROM. The use of cutoff percentages for the incidence of individual variables improved sensitivity for both conditions. Cervical scoring added to biophysical monitoring by improving the sensitivity for early delivery of patients in preterm labor.