Biophysical profile as a predictor of amniotic fluid culture results

The biophysical profile has been proposed as a noninvasive method of detecting fetal infection in patients with preterm premature rupture of membranes (PROM). The purpose of this study was to evaluate the biophysical profile as a rapid predictor of amniotic fluid (AF) culture results in women with PROM. Amniocentesis was performed on 111 patients with PROM at or before 34 weeks' estimated gestational age. Aerobic, anaerobic, Ureaplasma, and Mycoplasma cultures were performed on the AF. A biophysical profile was performed just before the amniocentesis. Women with positive AF cultures had a significantly lower total biophysical profile score, as well as significantly lower scores for nonstress test, fetal breathing movements, fetal movements, and AF volume, than those with negative AF cultures. However, neither the total biophysical profile score nor any of the individual components had sufficient sensitivity, specificity, or positive or negative predictive value to be useful clinically in predicting culture results. Although the incidence of positive AF cultures was inversely related to the biophysical profile score, 48% of patients with a score of 8 and 27% of those with a score of 10 had positive AF cultures. The results of this study do not support use of the biophysical profile as an early predictor of AF culture results in patients with PROM.