Objective: The study of fetal lung circulation by means of pulmonary Doppler investigation.
Methods: Pulmonary Doppler ultrasound obtained with color pulsed-Doppler with a 3.5- to 5-MHz probe. Measure of resistance index and pulsatility index.
Patients: 47 pregnant women with singleton, between 18 and 39.5 weeks of gestation, were recruited to have pulmonary Doppler ultrasound. Seven fetuses had intrauterine fetal growth retardation (IUGR). Overall, 50 Doppler velocity waveforms were measured.
Results: Resistance and pulsatility index were measured in all patients and at each examination. Resistance index (0.86 +/- 0.03) and pulsatility index (2.46 +/- 0.34) were found to be stable during pregnancy. Pulmonary pulsatility index in IUGR fetuses (2.71 +/- 0.33) were found to be higher than those in normotrophic infants (p = 0.006), whereas no difference was found in resistance index between the same subgroups. Moreover, no difference was found in pulsatility index measurements between preterm small-for-gestational age fetuses and normotrophic fetuses measured between 36 and 39.5 weeks of gestation (2.68 +/- 0.31 vs. 2.49 +/- 0.28).
Conclusion: Pulmonary resistance index is not statistically different between normotrophic and IUGR fetuses. In contrast, pulmonary pulsatility index is significantly higher in IUGR fetuses when compared to normotrophic fetuses. Pulmonary Doppler ultrasound should be evaluated in a larger trial and correlation between Doppler measurements and fetal lung maturation should be studied.