The role of doppler waveforms in the fetal main pulmonary artery in the prediction of neonatal respiratory distress syndrome.

Objective To describe changes in the Doppler waveforms of the fetal main pulmonary artery (MPA) throughout gestation and to assess their predictive value of neonatal respiratory distress syndrome (RDS). Study Design In the first phase of this study, we performed Doppler measurement of MPA acceleration time (AT), ejection time (ET), peak systolic velocity, end-diastolic velocity, mean velocity, pulsatility index, and resistance index in 288 healthy fetuses. In the second phase, we carried out these measurements in a prospective cohort of 52 pregnant women with impending preterm birth. Results In phase I, satisfactory fetal MPA Doppler recordings were collected in 284 of 288 (98.6%) normal fetuses. Significant and positive linear correlations were found between gestational age and AT, AT/ET ratio, peak systolic velocity, and mean velocity (p < 0.01), with the strongest correlations concerning AT (r = 0.898) and AT/ET ratio (r = 0.868). In phase II, satisfactory fetal MPA Doppler waveforms were obtained in 43 of 44 (97.7%) fetuses. Of these, 14 (32.6%) developed RDS and 29 did not. Using less than or equal to the fifth percentile as a gestational age-specific cutoff, AT alone could predict RDS with a sensitivity of 78.6% and a specificity of 89.7%. The AT/ET ratio could predict RDS with 71.4% sensitivity and 93.1% specificity. Conclusions Fetal MPA Doppler velocimetry can reliably be obtained throughout gestation. AT and AT/ET ratios of the fetal MPA Doppler waveform may help identifying fetuses at risk of developing neonatal RDS. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:375–383, 2015