Assessment of the Diagnostic Accuracy of the TDx-FLM II to Predict Fetal Lung Maturity

Background: Because respiratory distress syndrome (RDS) affects 1% of live births, accurate and rapid assessment of markers of fetal lung maturity is critical to clinicians in deciding whether to deliver a preterm infant. Our objective was to determine the optimal diagnostic cutoff value for the TDx-FLM II assay (Abbott Laboratories) for predicting clinically significant RDS. Methods: Amniotic fluid TDx-FLM II data were collected retrospectively over 4 years. Women were included in the study if they had delivered within 72 h of TDx-FLM II testing and both the mother and infant charts could be reviewed. Women who had been treated with steroids and delivered unaffected infants were excluded from the analysis. The diagnosis of RDS was defined as infants who either were treated with surfactant and/or were placed on a ventilator and/or required continuous positive airway pressure for >1 day. Results: A total of 185 women met all entry criteria (15 RDS, 170 non-RDS). A cutoff value for a mature result of ≥45 mg/g gave a sensitivity of 100% (95% confidence interval, 82–100%) and a specificity of 90% (95% confidence interval, 78–89%). Conclusions: The TDx-FLM II appears to predict clinically significant RDS when a cutoff of ≥45 mg/g is used for mature results. Further studies will be required to confirm these findings.