PERIPHERAL RIGHT PULMONARY-ARTERY BLOOD-FLOW VELOCIMETRY - DOPPLER SONOGRAPHIC STUDY OF NORMAL AND ABNORMAL FETUSES

The knowledge of fetal lung circulation in normal and abnormal human f etuses is limited. Our objectives were to assess normal values for flo w velocity waveforms in the fetal pulmonic circulation and to test the hypothesis that Doppler velocimetry can predict lung hypoplasia. In a cross-sectional study, peripheral right pulmonary artery flow velocim etry was investigated prospectively in 96 healthy fetuses between 14 a nd 37 weeks' gestation and four fetuses with abnormalities known to in duce lung hypoplasia. The pulsatility index was used to quantify the v elocity waveforms. In normal fetuses the mean pulsatility index in the peripheral right pulmonary artery was low, being equivalent to that c orresponding to 14 to 17 weeks' gestation (2.89; confidence interval = 2.35 to 3.42), increasing at midgestation to 3.44, with a confidence interval of 3.04 to 3.83; P < 0.01. Thereafter, during the late second and third trimesters the mean pulsatility index did not change signif icantly with GA, being 3.66 (confidence interval = 3.04 to 4.04) at te rm. In fetuses with proven lung hypoplasia, the pulsatility index meas urements were within the 95% confidence limits of those for normal fet uses. In a normal pregnancy, except for the early stages, a relatively stable high vascular resistance of the fetal pulmonary circulation wa s found. Our preliminary data suggest that the pulsatility index of th e lung circulation cannot be used as an indicator of-lung hypoplasia.