Amniotic fluid indices of fetal pulmonary maturity with preterm premature rupture of membranes

Abstract

Objective: To evaluate the performance of the TDx/TDxFLx fetal lung maturity II assay (Abbott Laboratories; Abbott Park, IL) on amniotic fluid (AF) specimens collected vaginally from women with preterm premature rupture of membranes (PROM). Methods: We reviewed charts of patients with preterm PROM treated at Shands Hospital at the University of Florida from January 1, 1995, to June 30, 1999. Negative predictive values (prediction of the absence of neonatal respiratory distress) of mature (at or above 55 mg/g) and borderline (40–54 mg/g) test results were calculated for 153 women. Results: Respiratory distress syndrome (RDS) occurred with frequencies of one in 42 and three in 29 cases with mature and borderline test results, respectively. All cases of RDS were mild, defined as sustained tachypnea with or without need for supplemental oxygen. With an immature (less than 40 mg/g) test result, 20 of 82 infants developed RDS, and half of those cases were severe, defined as needing mechanical ventilation. Negative predictive values of mature and borderline tests were 97.6% (95% confidence interval [CI] 92.9, 100) and 89.7% (95% CI, 78.3, 100), respectively. Conclusion: Mature results from fetal lung maturity tests of vaginally collected AF predict the absence of RDS with a high degree of accuracy.